sadpandajoe commented on code in PR #43870:
URL: https://github.com/apache/superset/pull/43870#discussion_r4330415114
##########
superset/db_engine_specs/postgres.py:
##########
@@ -178,6 +178,9 @@ class PostgresBaseEngineSpec(BaseEngineSpec):
engine = ""
engine_name = "PostgreSQL"
+ # The engine's default text comparison is binary, so a mirrored
+ # ``partition_col = T(v)`` agrees with the ``col = v`` it stands in for.
+ binary_string_comparison = True
Review Comment:
Netezza inherits this flag through `PostgresBaseEngineSpec`, but its string
comparison ignores trailing spaces (unlike PostgreSQL's binary comparison).
With VARCHAR columns and a transform like `:value || 'x'`, the row
`(country='US', p='USx')` satisfies `country = 'US '`, yet the mirrored
predicate asks for `p = 'US x'` and silently drops it. Should this be declared
on the concrete specs where binary comparison is verified instead of on the
shared base?
##########
superset/connectors/sqla/partition_mapping.py:
##########
@@ -0,0 +1,3524 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""
+Partition filter mapping.
+
+Datasets on Hadoop-family engines are commonly partitioned on a *technical*
+column -- an epoch integer, a lowercased region key -- that no analyst would
+filter on. Unless a query carries a predicate on that column the engine scans
+every partition.
+
+A dataset owner names one partition column ``p``, one business column that
+filters are mirrored from, and a value transform ``T`` (a SQL expression
+containing a ``:value`` placeholder). Superset then appends an equivalent
+predicate on ``p`` to every query, so chart authors change nothing and queries
+prune.
+
+The load-bearing assumption
+---------------------------
+Everything here reasons about ``T(col) op T(v)``, but what is emitted is
+``p op T(v)`` -- a predicate on a *physically different column*. The step from
+one to the other is::
+
+ p = T(mapped_col) for every row in the table
+
+Superset cannot verify that; it is a property of whatever ETL populates the
+partition column. If that job lags, backfills with different logic, or writes
+the partition key in a different timezone, mirrored predicates silently drop
+real rows. The mapping is only as trustworthy as the pipeline behind it.
+
+Operator safety
+---------------
+A mirrored predicate ``P2`` may only be ``AND``-ed onto a query when the
+original predicate ``P1`` *implies* it:
+
+=========================================== =============================
+Original Safe when
+=========================================== =============================
+``col = v``, ``col IN (...)`` ``T`` is a function *and* the
+ engine compares ``col``
+ byte-exactly
+``col >=|>|<|<= v``, ``TEMPORAL_RANGE`` only if ``T`` is monotonic
+``col != v``, ``NOT IN``, ``LIKE``, ... never
+=========================================== =============================
+
+Monotonic here means non-decreasing, not strictly increasing: a bucketing
+transform such as a day key is monotonic and maps a whole day of timestamps
+onto one value. ``col < v`` then only implies ``T(col) <= T(v)``, so a strict
+bound is mirrored non-strictly -- see `mirror_operator`.
+
+Equality under the engine's own rules
+-------------------------------------
+"``T`` is a function" gives ``col = v`` implies ``T(col) = T(v)`` for *value*
+equality. The engine compares with *SQL* equality, and the two part company
+wherever that comparison is not byte-exact: under a case-insensitive collation
+a stored ``country`` of ``'us'`` satisfies a filter for ``'US'``, while the
+mirror ``region_key = hex('US')`` excludes the row and the chart loses it with
+nothing to indicate why. Trailing-space-insensitive ``CHAR`` comparison says
+the same thing about padding.
+
+So equality and ``IN`` are withdrawn for a *string* mapped column unless the
+engine spec declares ``binary_string_comparison`` -- `equality_mirrors_safely`.
+Numeric and temporal comparison is exact everywhere and is untouched, and range
+mirroring is untouched too: it already rests on the owner declaring ``T``
+order-preserving *with respect to the column's own order*, which is an
+assertion about the very semantics this is checking for.
+
+What the gate cannot see is a column declaring its own collation
+(``country COLLATE NOCASE``) on an otherwise byte-exact engine. Nothing in
+SQLAlchemy's reflection or the engine specs exposes that, so there it remains
+the owner's assumption, like ``p = T(mapped_col)`` itself.
+
+Resolution of the value the engine compares
+-------------------------------------------
+Every row of the table above assumes the engine compares the value the mirror
+was built from. It does not always. A ``DATE`` column compared against
+``'2026-07-06 10:08:11'`` is compared on the date part alone -- whether the
+engine writes the literal itself (``TO_DATE('2026-07-06', 'YYYY-MM-DD')`` on
+Postgres, ``DATE '2026-07-06'`` on Presto, Trino, BigQuery and some two dozen
+others) or applies an implicit cast to a bound string. The filter therefore
+keeps the whole of that day while ``p = T(2026-07-06 10:08:11)`` keeps one
+instant of it: narrower than the predicate it stands in for, which is the one
+thing a mirror may never be.
+
+What an engine throws away is detected from the column's type rather than
+enumerated per engine -- `ExploreMixin._engine_literal_resolution` -- and what
+to do about it is a property of the *operator*, not of the value:
+
+* a bound rounds outward, backward for a lower one and forward for an upper
one,
+ through `ExploreMixin._round_bounds_outward`. The mirror then reads one extra
+ bucket at the edge, and the original predicate is still in the query to
+ exclude the rows that bucket adds.
+* an equality, or one member of an ``IN`` list, has nowhere to widen to: these
+ predicates are ``AND``-ed onto the query, so "or the day either side" is not
+ something the mirror can express. They decline, which costs the query its
+ pruning and nothing else.
+
+So a ``DATE``-typed mapped column mirrors a range at day granularity, and does
+not mirror an equality whose value carries a time of day at all. Map a
+``TIMESTAMP`` column instead and every operator is available again.
+
+Writing the value into the probe
+--------------------------------
+The probe evaluates the transform at a *literal*, because it runs with no bound
+parameters at all -- so every value is written into SQL text by the driver's
+literal renderer and read back by the engine's lexer, and the two do not always
+agree. SQLAlchemy's default renderer doubles apostrophes and leaves backslashes
+alone; Hive honours backslash escapes and not doubling, so ``'O''Brien'`` is
+read there as two adjacent literals and ``'x\\''`` ends four characters into a
+value the filter carries whole. A disagreement is either a mirror built from a
+value nobody filtered on -- dropping rows the filter keeps -- or, where the
+value closes its own quote, an expression of the filterer's choosing running in
+the probe.
+
+Which side is right is not knowable from the driver: it is a per-session server
+setting (``standard_conforming_strings``, ``NO_BACKSLASH_ESCAPES``,
+``spark.sql.parser.escapedStringLiterals``), and SQLAlchemy's own view of it is
+only correct on a dialect that has connected. So escaping is not what makes
+this safe. `literal_round_trips` renders the literal and reads it back in the
+engine's own dialect instead, and a value that does not survive the trip is not
+mirrored -- the usual trade, pruning for correctness. `probe_sql_is_evaluable`
+re-reads the finished statement behind it.
+
+The probe's *answers* make the same trip, in the other direction. The chart
+query is compiled with ``literal_binds``, so a probed partition key is rendered
+into its SQL by the same renderer and read by the same lexer -- and
+``concat(:value, chr(92), 'b')`` turns the unremarkable input ``a`` into the
key
+``a\\b``, which Hive reads back as ``a`` followed by a backspace. So
+`_predicates_from_probe` asks `literal_round_trips` about each result too, and
+declines the request rather than emitting a predicate no row can satisfy: the
+mirror is ``AND``-ed onto the query, so a mirror that matches nothing costs the
+chart its rows rather than its pruning.
+
+Negations are never safe because ``T`` need not be injective:
+``lower(:value)`` with ``country != 'US'`` mirrors to ``region_key != 'us'``,
+which wrongly excludes rows whose ``country`` is already lowercase ``'us'`` --
+rows the original filter *keeps*.
+
+Monotonicity is a property of the transform, not of the column's data type:
+``hour(:value)``, ``date_format(:value, 'dd')`` and ``dayofweek(:value)`` are
+all reasonable transforms on a ``TIMESTAMP`` column and none of them preserve
+ordering. It is therefore declared by the owner, not inferred.
+
+Time grains
+-----------
+A grained filter -- drill-to-detail, mostly -- compares the *truncated* column,
+``trunc(col) op v``, so the raw bounds it carries do not describe the rows it
+keeps. A row in the final partial bucket satisfies ``trunc(col) < until`` while
+``col < until`` excludes it.
+
+Which direction a grain rounds is not knowable from the duration alone, and the
+obvious guess is wrong: ``WEEK_ENDING_SATURDAY`` rounds *forward* on Hive and
+Presto, and Ocient's grains are ``ROUND``, i.e. to nearest. What every grain
+does satisfy is a bound on the displacement::
+
+ |trunc(ts) - ts| < width(grain)
+
+so widening *both* bounds by one bucket width is no narrower than the real
+predicate whichever way the grain rounds -- and it needs no monotonicity of
+``trunc`` itself, which is what rescues Hive's oddly-anchored ``P1W``. Width is
+a property of the grain, not of the engine, which is what makes this
+maintainable; see `grain_bucket_width`. A grain whose SQL an operator supplied
+has no known width, and does not mirror at all.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import logging
+import numbers
+import re
+from collections.abc import Sequence
+from dataclasses import dataclass
+from datetime import date, datetime
+from functools import lru_cache
+from typing import Any, cast, TYPE_CHECKING
+
+import numpy as np
+import pandas as pd
+import sqlalchemy as sa
+from dateutil.relativedelta import relativedelta
+from flask import current_app as app
+from flask_babel import lazy_gettext as _
+from sqlalchemy.engine.interfaces import Dialect
+from sqlalchemy.sql.elements import ColumnElement
+
+from superset.constants import LRU_CACHE_MAX_SIZE, TimeGrain
+from superset.exceptions import (
+ QueryClauseValidationException,
+ SupersetParseError,
+ SupersetSecurityException,
+)
+from superset.extensions import cache_manager, feature_flag_manager
+from superset.sql.parse import SQLScript, SQLStatement
+from superset.superset_typing import FilterValues
+from superset.utils import core as utils, json
+from superset.utils.core import FilterOperator, get_username
+
+if TYPE_CHECKING:
+ from superset.connectors.sqla.models import SqlaTable, TableColumn
+ from superset.db_engine_specs.base import BaseEngineSpec
+ from superset.models.core import Database
+
+logger = logging.getLogger(__name__)
+
+FEATURE_FLAG = "PARTITION_FILTER_MAPPING"
+
+#: Longest transform accepted anywhere. A transform is one SQL expression an
+#: owner types by hand, so this is generous; the point is that it is bounded.
+#: The bound matters because `is_transform_active` parses the stored value on
+#: each Explore load, and an unbounded string would make that parse the
+#: expensive part of rendering a chart.
+#:
+#: The typed column field, the import schema and the preview request each
+#: enforce it through a marshmallow `Length` validator, which is what produces
+#: the per-field message those three callers want. `stored_expression_error`
+#: enforces it too, for the paths that load no schema -- the deprecated
+#: `POST /datasource/save/` is one, and it writes straight through
+#: `update_from_object`.
+MAX_TRANSFORM_LENGTH = 1024
+
+#: Placeholder the owner writes in the transform, e.g.
``unix_timestamp(:value)``.
+#: Matched with word boundaries so ``:values`` is not mistaken for it.
+VALUE_PLACEHOLDER_RE = re.compile(r":value\b")
+
+#: The opening and closing delimiters of each kind of Jinja block. The probe
+#: would render these in a different context at a different time from the chart
+#: query, so a transform holding one is rejected at save time.
+JINJA_BLOCK_DELIMITERS = (("{{", "}}"), ("{%", "%}"), ("{#", "#}"))
+
+#: MySQL and MariaDB "executable comments": ``/*!50000 ... */`` and
+#: ``/*M!50000 ... */`` are comments to every other reader and *statement text*
+#: to those two engines.
+#:
+#: This is the one construct that breaks the premise the probe's shape gates
+#: rest on -- that the parse this module inspects and the statement the engine
+#: runs are the same statement. ``1 /*!50000 + (SELECT secret FROM vault) */``
+#: parses with no sub-query and no FROM, clears `stored_expression_error` and
+#: `probe_sql_is_evaluable` alike, and then reads a table on MySQL. The result
+#: comes back to a dataset owner through the preview's ``emitted_predicate``,
+#: with no RLS applied and no SQL Lab access needed.
+#:
+#: Refused on every engine rather than only the two that honour it. A transform
+#: is a scalar function of ``:value``; there is no legitimate reason for one to
+#: carry a comment of any kind, let alone this one, and a per-engine gate would
+#: store a transform on Postgres that detonates when the dataset is re-pointed
+#: at MySQL.
+EXECUTABLE_COMMENT_RE = re.compile(r"/\*M?!")
+
+#: A PostgreSQL Unicode-escaped identifier, ``U&"..."``.
+#:
+#: The second construct that breaks the premise above, and in the same way:
+#: ``U&"\\0071uery_to_xml"(...)`` parses as an anonymous function whose name is
+#: the *literal* ``\\0071uery_to_xml``, so the function denylist is matching a
+#: name the engine never sees -- PostgreSQL decodes the escape and runs
+#: ``query_to_xml``, handing a dataset owner rows from outside their RLS scope
+#: through the preview's ``emitted_predicate``.
+#:
+#: Normalizing the escapes and re-checking would be the other repair, and is
+#: worse: it means reimplementing one engine's identifier decoding well enough
+#: to be a security boundary. Refusing the construct is exact, and costs
+#: nothing real -- a transform is a scalar function of ``:value``, and there is
+#: no reason to name a function or column through an escape sequence.
+#:
+#: Refused on every engine, like the executable comment, so a transform stored
+#: on SQLite cannot detonate when the dataset is re-pointed at PostgreSQL. The
+#: ``&`` may be separated from the ``U`` by nothing at all, but whitespace or a
+#: comment between the prefix and the string is not accepted by PostgreSQL
+#: either, so the strict form is the whole surface.
+#:
+#: Matched in raw text, so the prefix is refused inside a string literal too.
+#: That is the same trade the executable comment makes and has the same
+#: justification: a gate whose contract is to fire *before* the parse cannot
+#: ask the parse whether the text was quoted. ``concat(:value, 'u&"x"')`` is
+#: refused, which costs an owner nothing anyone writes.
+UNICODE_ESCAPED_IDENTIFIER_RE = re.compile(r'\bU&"', re.IGNORECASE)
+
+#: Substituted for ``:value`` before parsing -- sqlglot rejects a bare
``:value``
+#: on most dialects. Mirrors the ``_JINJA_BLOCK_RE`` -> ``NULL`` trick used by
+#: ``validate_stored_expression``.
+_PARSE_STANDIN = "NULL"
+
+#: Substituted for ``:value`` to find out *where* the placeholder landed, which
+#: `_PARSE_STANDIN` cannot answer: ``NULL`` is a keyword, so after substitution
+#: the parse tree no longer records that a placeholder was ever there. An
+#: identifier does leave a trace -- a column reference -- and one that is
+#: missing is a placeholder the engine will never evaluate.
+#:
+#: Named so it cannot plausibly collide with a real column, but a transform
that
+#: writes it anyway is refused rather than counted. A hand-written occurrence
+#: does not merely make the count disagree: it *supplies* the column reference
a
+#: non-executable placeholder failed to produce, and the two cancel exactly.
See
+#: `placeholder_is_executable`.
+_PLACEHOLDER_STANDIN = "superset_pfm_value_standin"
+
+#: Functions whose value depends on wall-clock time or randomness. The probe
+#: runs in a different session at a different moment from the chart query and
+#: its result is then cached, so any of these freezes a snapshot of probe time
+#: into the emitted predicate: a transform such as
+#: ``datediff(day, :value, LOCALTIMESTAMP)`` for a relative partition key is
+#: evaluated once and then keeps emitting yesterday's answer, so the chart
+#: silently drops rows after midnight.
+#:
+#: Matched by SQL function name, so every engine's spelling of "now" has to be
+#: named -- the ANSI four were not enough. Listed rather than delegated to the
+#: engine specs because the risk is the same everywhere and a spec that had not
+#: got round to declaring its own would fail open; a name no engine has is
+#: inert, so over-listing costs nothing.
+NON_DETERMINISTIC_FUNCTIONS = {
+ # ANSI, and the engines that spell it this way.
+ "CURRENT_DATE",
+ "CURRENT_TIME",
+ "CURRENT_TIMESTAMP",
+ "LOCALTIME",
+ "LOCALTIMESTAMP",
+ "NOW",
+ "RAND",
+ "RANDOM",
+ "UUID",
+ # PostgreSQL. `now()` is statement-stable; these two are not even that.
+ "CLOCK_TIMESTAMP",
+ "STATEMENT_TIMESTAMP",
+ "TIMEOFDAY",
+ # MySQL and MariaDB.
+ "CURDATE",
+ "CURTIME",
+ "SYSDATE",
+ "UTC_DATE",
+ "UTC_TIME",
+ "UTC_TIMESTAMP",
+ "UUID_SHORT",
+ # Oracle.
+ "SYSTIMESTAMP",
+ "SYS_GUID",
+ # SQL Server.
+ "GETDATE",
+ "GETUTCDATE",
+ "SYSDATETIME",
+ "SYSUTCDATETIME",
+ "SYSDATETIMEOFFSET",
+ "NEWID",
+ # BigQuery.
+ "CURRENT_DATETIME",
+ "GENERATE_UUID",
+ # Snowflake.
+ "RANDSTR",
+ "UUID_STRING",
+ # ClickHouse.
+ "NOW64",
+ "RANDCANONICAL",
+ "GENERATEUUIDV4",
+ # H2 and Derby, which the test fixtures use.
+ "RANDOM_UUID",
+}
+
+#: The wall-clock names an engine evaluates with no parentheses at all.
+#:
+#: These parse as *column references*, not functions, so the name-based walk
+#: below cannot see them: `datediff(UTC_DATE, :value)` on MySQL and
+#: `:value - SYSDATE` on Oracle both cleared the gate and froze probe time into
+#: a cached mirror.
+#:
+#: A subset of `NON_DETERMINISTIC_FUNCTIONS` rather than the whole of it,
+#: because refusing a bare name costs an owner a column genuinely called that.
+#: Only the names SQL lets you write without ``()`` are listed -- the datetime
+#: keywords -- so `rand`, `uuid` and `newid`, which always need parentheses and
+#: are plausible column names, stay out.
+BARE_WALL_CLOCK_KEYWORDS = frozenset(
+ {
+ "current_date",
+ "current_time",
+ "current_timestamp",
+ "localtime",
+ "localtimestamp",
+ "utc_date",
+ "utc_time",
+ "utc_timestamp",
+ "sysdate",
+ "systimestamp",
+ }
+)
+
+#: Functions that mean "now" only in their zero-argument form. On Hive and
+#: Impala ``unix_timestamp()`` is the current time while ``unix_timestamp(x)``
+#: -- the canonical transform for this feature -- is pure.
+NON_DETERMINISTIC_WHEN_NILADIC = {"UNIX_TIMESTAMP"}
+
+#: Safe for any function ``T``.
+MIRRORABLE_ALWAYS = {FilterOperator.EQUALS, FilterOperator.IN}
+
+#: Safe only when ``T`` preserves ordering.
+MIRRORABLE_IF_MONOTONIC = {
+ FilterOperator.GREATER_THAN,
+ FilterOperator.GREATER_THAN_OR_EQUALS,
+ FilterOperator.LESS_THAN,
+ FilterOperator.LESS_THAN_OR_EQUALS,
+ FilterOperator.TEMPORAL_RANGE,
+}
+
+
+#: Every operator that can be mirrored under *some* transform. The preview
+#: endpoint accepts these; whether a given one actually mirrors still depends
on
+#: the monotonicity declaration.
+MIRRORABLE_OPERATORS = MIRRORABLE_ALWAYS | MIRRORABLE_IF_MONOTONIC
+
+#: Operators the preview endpoint can construct. `TEMPORAL_RANGE` is mirrored
by
+#: the query path, but as *two* bounds that `_collect_partition_mirror_range`
+#: decomposes a time range into -- the preview request carries sample values,
not
+#: a since/until pair, so there is no range for it to build. The editor never
+#: asks for one either: `previewOperatorFor` sends `>=`, `=` or `IN`.
+PREVIEWABLE_OPERATORS = MIRRORABLE_OPERATORS - {FilterOperator.TEMPORAL_RANGE}
+
+
+class Unmirrorable:
+ """
+ A filter no mirror can stand in for, and why.
+
+ Returned by `ExploreMixin.mirror_probe_request` for a value the engine
+ compares more coarsely than the filter carries, one it cannot render as a
+ literal, one whose rendered literal the engine would not read back as the
+ same value, one in a time frame the transform would discard, or an ``IN``
+ list with a member of any of those kinds. An object rather than `None`,
+ because `None` is a filter value in its own right.
+
+ The reason rides along because the preview has to explain the decline to
+ the owner, and the two declines want different advice: "the engine compares
+ less of this value than you typed, so map a column it compares in full" is
+ sound guidance for a `DATE` column and actively misleading for an
+ offset-bearing bound on a `TIMESTAMP` one, which already is such a column.
+ Carried rather than re-derived so the preview's explanation cannot come
+ apart from the chart path's decision.
+
+ Lives here rather than beside that method so the preview can read it too:
+ `superset.models.helpers` imports this module, so these can only cross the
+ boundary in this direction. Both callers recognise the same instances -- a
+ preview that answered "valid" for a request the chart path declines is the
+ drift this is here to prevent.
+ """
+
+ __slots__ = ("reason",)
+
+ def __init__(self, reason: str) -> None:
+ self.reason = reason
+
+ def __repr__(self) -> str:
+ return f"<Unmirrorable {self.reason}>"
+
+
+#: The ordinary decline: whatever the mirror cannot be built from, with the
+#: engine's own comparison resolution as the reason an owner can act on.
+UNMIRRORABLE = Unmirrorable("resolution")
+
+#: A value carrying a UTC offset, declined whatever the column's resolution.
+#: A transform such as ``CAST(:value AS TIMESTAMP)`` drops the offset, so even
+#: an engine that compares the whole instant would be probed in the wrong
+#: frame -- which is not something mapping a different column fixes.
+UNMIRRORABLE_OFFSET = Unmirrorable("offset")
+
+#: A value the driver and the engine would not spell the same way, declined
+#: whatever the column's resolution and whatever the operator. Nothing about
+#: the column or the transform fixes it -- see `literal_round_trips` -- so the
+#: advice the resolution reason carries would send an owner after the wrong
+#: thing entirely.
+UNMIRRORABLE_ESCAPING = Unmirrorable("escaping")
+
+
+def is_unmirrorable(value: Any) -> bool:
+ """Whether `mirror_probe_request` declined this request."""
+ return isinstance(value, Unmirrorable)
+
+
+#: A transform that preserves ordering need not be *strictly* increasing: a day
+#: key such as ``to_char(ts, 'YYYYMMDD')`` maps a whole day of timestamps onto
+#: one value. For such a ``T``, ``col < v`` only implies ``T(col) <= T(v)`` and
+#: ``col > v`` only implies ``T(col) >= T(v)`` -- the rows in the bucket at the
+#: boundary satisfy the non-strict form and not the strict one. A strict mirror
+#: therefore drops rows the filter keeps, which is the one thing a mirror may
+#: never do, so a strict bound is mirrored non-strictly.
+_NON_STRICT_EQUIVALENT = {
+ FilterOperator.GREATER_THAN: FilterOperator.GREATER_THAN_OR_EQUALS,
+ FilterOperator.LESS_THAN: FilterOperator.LESS_THAN_OR_EQUALS,
+}
+
+
+def mirror_operator(operator: FilterOperator) -> FilterOperator:
+ """
+ The operator a mirrored predicate uses to stand in for ``operator``.
+
+ Strict bounds widen; everything else passes through. Idempotent, so it is
+ safe wherever a request may already have been widened.
+
+ The widened bound reads one extra partition at the edge, and the original
+ predicate is still in the query to exclude the rows that partition adds --
+ the same trade as the grain widening and the ``NULL``-partition escape.
+ Declaring the transform strictly increasing would buy that partition back,
+ which is not worth a second property only the owner can vouch for.
+ """
+ return _NON_STRICT_EQUIVALENT.get(operator, operator)
+
+
+def mirrorable_operators(
+ is_monotonic: bool, *, equality_is_safe: bool = True
+) -> set[FilterOperator]:
+ """
+ The operators whose predicates may be mirrored onto the partition column.
+
+ :param is_monotonic: whether the owner declared the transform
+ order-preserving
+ :param equality_is_safe: whether the engine's ``=`` on the mapped column
+ compares the way ``T`` was written against -- see
+ `equality_mirrors_safely`
+
+ Both call sites -- the query path through `PartitionMapping.mirrors` and
the
+ Explore indicator through `partition_filter_mapping_summary` -- come
through
+ here, which is what keeps the glyph from promising pruning the SQL will not
+ do.
+ """
+ operators = MIRRORABLE_ALWAYS if equality_is_safe else set()
+ if is_monotonic:
+ operators = operators | MIRRORABLE_IF_MONOTONIC
+ return set(operators)
+
+
+def _native_generic_type(
+ column: "TableColumn",
+) -> utils.GenericDataType | None:
+ """
+ What the engine spec makes of ``column``'s declared type.
+
+ `TableColumn.type_generic` answers ``TEMPORAL`` for every column carrying
+ ``is_dttm``, which is the right answer for a chart's time axis and the
+ wrong one for a comparison: an epoch ``BIGINT`` is a number to the engine
+ however it is labelled here. Falls back to the flag where the spec has no
+ answer, so a type Superset cannot resolve is no worse off than before.
+ """
+ try:
+ column_spec = column.db_engine_spec.get_column_spec(
+ column.type, db_extra=column.db_extra
+ )
+ except Exception: # pylint: disable=broad-except # noqa: BLE001
+ column_spec = None
+ if column_spec is not None and column_spec.generic_type is not None:
+ return column_spec.generic_type
+ try:
+ return column.type_generic
+ except Exception: # pylint: disable=broad-except # noqa: BLE001
+ return None
+
+
+#: Declared types whose comparison ignores trailing blanks.
+#:
+#: The fixed-width character types, which the SQL standard has compare as
+#: though both sides were padded to the same length -- so ``'US'`` and
+#: ``'US '`` are equal in a ``CHARACTER(3)``, while ``lower()`` of the two is
+#: not. Spelled out rather than matched by prefix because the variable-width
+#: names start with the same letters: ``VARCHAR`` and ``CHARACTER VARYING``
+#: compare the blanks and must not land here.
+PADDED_CHARACTER_TYPES = frozenset(
+ {
+ "CHAR",
+ "NCHAR",
+ # PostgreSQL's own name for ``CHARACTER``, which is what reflection
+ # reports for a ``CHAR(n)`` column there.
+ "BPCHAR",
+ "CHARACTER",
+ "NATIONAL CHAR",
+ "NATIONAL CHARACTER",
+ }
+)
+
+
+def _is_padded_character_type(column: TableColumn) -> bool:
+ """
+ Whether ``column``'s declared type compares without its trailing blanks.
+
+ Read off the declared type rather than the engine spec's resolved one: the
+ specs map ``CHAR`` and ``VARCHAR`` onto the same `sqlalchemy.String`, so
+ the distinction this needs is gone by then. The length suffix is dropped
+ and the name matched against `PADDED_CHARACTER_TYPES`, so an unfamiliar
+ spelling answers ``False`` and the engine-level flag decides as before --
+ this gate adds a decline rather than lifting one. A column with no
+ declared type has nothing to read, and answers the same way.
+ """
+ if not isinstance(column.type, str):
+ return False
+ native = re.sub(r"\s+", " ", column.type.strip().upper())
+ return native.split("(")[0].strip() in PADDED_CHARACTER_TYPES
+
+
+def equality_mirrors_safely(
+ column: TableColumn | None,
+ db_engine_spec: type[BaseEngineSpec],
+) -> bool:
+ """
+ Whether ``col = v`` on this column implies ``T(col) = T(v)`` in the engine.
+
+ The operator matrix calls equality safe "for any function ``T``" because
+ ``T`` is a function, so ``col = v`` gives ``T(col) = T(v)``. That reasons
+ about *value* equality while the engine reasons about *SQL* equality, and
+ the two part company under any comparison that is not byte-exact: with a
+ case-insensitive collation a stored ``country`` of ``'us'`` satisfies a
+ filter for ``'US'``, but the mirror ``region_key = hex('US')`` excludes the
+ row and the chart loses it with no indication why.
Trailing-space-insensitive
+ ``CHAR`` comparison says the same thing about padding.
+
+ Only string columns are at risk; numeric and temporal comparison is exact
+ everywhere. And only equality: range mirroring already requires the owner
+ to declare ``T`` order-preserving *with respect to the column's own order*,
+ which is an assertion about the same comparison semantics this is checking
+ for -- so the declaration covers it where equality has nothing to cover it.
+
+ Padding is asked about per column, because it is a property of the *type*
+ rather than of the engine. ``binary_string_comparison`` speaks for an
+ engine's default text comparison, and on PostgreSQL -- which declares it
+ -- a ``CHAR(2)`` still matches a filter for ``'US '`` against a stored
+ ``'US'``, because the standard says a padded character type compares
+ without its trailing blanks. The mirror ``region_key = lower('US ')`` then
+ excludes the row. So a fixed-width character type declines whatever the
+ engine says, and an engine that ignores trailing blanks on its *variable*
+ types says so by not declaring the flag at all (see `RedshiftEngineSpec`).
+
+ The type asked for is the engine spec's reading of the column's declared
+ type, not `TableColumn.type_generic`, which answers ``TEMPORAL`` for
+ anything carrying ``is_dttm``. A ``VARCHAR`` flagged temporal is still text
+ to the engine: on MySQL a filter for ``'2026-01-01T00:00:00'`` matches a
+ stored ``'...t00:00:00'``, while the mirror ``p = hex('...T...')`` excludes
+ it -- and asking the semantic flag skipped the check entirely.
+
+ A type the spec cannot classify declines, which is what the paragraph above
+ promises and what only the exception branch used to do. PostgreSQL's
+ ``citext`` matches no type pattern, so it answered ``None`` -- neither
+ string nor not-string -- and was waved through, which is precisely wrong
+ for a type whose whole purpose is case-insensitive comparison. Declining
+ costs the pruning; admitting it costs rows.
+
+ What this cannot see is a column that declares its own collation
+ (``country COLLATE NOCASE``) on an otherwise byte-exact engine. Neither
+ SQLAlchemy's reflection nor the engine specs expose it, so on such a column
+ the assumption stays where ``p = T(mapped_col)`` already is: with the
owner.
+ """
+ if column is None:
+ return True
+ # Ahead of the generic-type question, which a padded type can lose: the
+ # specs map ``CHARACTER`` onto no generic type at all on some engines, and
+ # a fixed-width character type is a string whether or not Superset can say
+ # so from the name.
+ if _is_padded_character_type(column):
+ return False
+ generic_type = _native_generic_type(column)
+ if generic_type is None:
+ return False
+ if generic_type != utils.GenericDataType.STRING:
+ return True
+ return bool(db_engine_spec.binary_string_comparison)
+
+
+#: How wide one bucket of each built-in time grain is.
+#:
+#: Keyed on the ISO duration a filter carries in its ``grain``. Written out
+#: rather than parsed: four of the week grains are ISO *intervals* with an
+#: anchor (``P1W/1970-01-03T00:00:00Z``) that ``isodate.parse_duration``
+#: rejects outright, and ``PT0.5H`` / ``P0.25Y`` are fractional. A literal
+#: table is also the thing a reviewer can check a line at a time.
+#:
+#: ``relativedelta`` rather than ``timedelta`` so the calendar grains stay
+#: calendar arithmetic: a month is not 30 days.
+GRAIN_BUCKET_WIDTHS: dict[str, relativedelta] = {
+ TimeGrain.SECOND: relativedelta(seconds=1),
+ TimeGrain.FIVE_SECONDS: relativedelta(seconds=5),
+ TimeGrain.THIRTY_SECONDS: relativedelta(seconds=30),
+ TimeGrain.MINUTE: relativedelta(minutes=1),
+ TimeGrain.FIVE_MINUTES: relativedelta(minutes=5),
+ TimeGrain.TEN_MINUTES: relativedelta(minutes=10),
+ TimeGrain.FIFTEEN_MINUTES: relativedelta(minutes=15),
+ TimeGrain.THIRTY_MINUTES: relativedelta(minutes=30),
+ TimeGrain.HALF_HOUR: relativedelta(minutes=30),
+ TimeGrain.HOUR: relativedelta(hours=1),
+ TimeGrain.SIX_HOURS: relativedelta(hours=6),
+ TimeGrain.DAY: relativedelta(days=1),
+ TimeGrain.WEEK: relativedelta(days=7),
+ TimeGrain.WEEK_STARTING_SUNDAY: relativedelta(days=7),
+ TimeGrain.WEEK_STARTING_MONDAY: relativedelta(days=7),
+ TimeGrain.WEEK_ENDING_SATURDAY: relativedelta(days=7),
+ TimeGrain.WEEK_ENDING_SUNDAY: relativedelta(days=7),
+ TimeGrain.MONTH: relativedelta(months=1),
+ TimeGrain.QUARTER: relativedelta(months=3),
+ TimeGrain.QUARTER_YEAR: relativedelta(months=3),
+ TimeGrain.YEAR: relativedelta(years=1),
+}
+
+
+def grain_bucket_width(grain: str | None, engine: str) -> relativedelta | None:
+ """
+ How far a grain's truncation can move a timestamp, or ``None`` if unknown.
+
+ A grained filter compares the *truncated* column, so the raw bounds it
+ carries do not describe the rows it keeps. Widening both bounds by one
+ bucket recovers a predicate that is no narrower than the real one -- see
+ `_collect_partition_mirror_range` for the argument. That only works for a
+ grain whose bucket width Superset knows, which excludes anything an
+ operator supplied.
+
+ :param grain: the ISO duration from the filter's ``grain``
+ :param engine: the engine spec's ``engine``, to check per-engine overrides
+ """
+ if not grain:
+ return None
+
+ # An operator-declared grain carries whatever duration string they typed,
+ # and `TIME_GRAIN_ADDON_EXPRESSIONS` can redefine a *built-in* grain's SQL
+ # per engine -- `P1D` could be anything at all. Neither has a width we can
+ # claim to know, so both fall back to not mirroring.
+ if grain in app.config["TIME_GRAIN_ADDONS"]:
+ return None
+ if grain in app.config["TIME_GRAIN_ADDON_EXPRESSIONS"].get(engine, {}):
+ return None
+
+ return GRAIN_BUCKET_WIDTHS.get(grain)
+
+
+@dataclass(frozen=True)
+class PartitionMapping:
+ """A resolved, usable partition filter mapping."""
+
+ partition_column: str
+ mapped_column: str
+ value_transform: str
+ is_monotonic: bool
+ #: Whether the engine compares the mapped column the way ``T`` was written
+ #: against. Resolved once where the column and the engine are both in hand,
+ #: rather than re-derived at each `mirrors` call.
+ equality_is_safe: bool = True
+
+ def mirrors(self, operator: FilterOperator) -> bool:
+ return operator in mirrorable_operators(
+ self.is_monotonic, equality_is_safe=self.equality_is_safe
+ )
+
+
+def contains_value_placeholder(transform: str | None) -> bool:
+ """Whether the transform contains the ``:value`` placeholder."""
+ return bool(transform) and VALUE_PLACEHOLDER_RE.search(transform or "") is
not None
+
+
+def contains_executable_comment(transform: str | None) -> bool:
+ """Whether the transform carries a MySQL/MariaDB executable comment.
+
+ See `EXECUTABLE_COMMENT_RE`. Answered on raw text, like
+ `contains_jinja` and for the same reason: the whole point is that no
+ parser this module can reach reports the construct at all.
+ """
+ return bool(transform) and EXECUTABLE_COMMENT_RE.search(transform or "")
is not None
+
+
+def contains_unicode_escaped_identifier(transform: str | None) -> bool:
+ """Whether the transform names something through a ``U&"..."`` escape.
+
+ See `UNICODE_ESCAPED_IDENTIFIER_RE`. Answered on raw text for the same
+ reason as the comment above: the parse reports a name the engine does not
+ use, which is exactly what makes the denylist blind to it.
+ """
+ return (
+ bool(transform)
+ and UNICODE_ESCAPED_IDENTIFIER_RE.search(transform or "") is not None
+ )
+
+
+#: Sequence pseudo-columns, which advance a sequence when they are *read*.
+#:
+#: ``orders_seq.NEXTVAL`` parses as a qualified column reference, not a
+#: function call, so neither `SQLStatement.is_mutating` -- which walks function
+#: names -- nor the function denylist can see it. The probe would then run
+#: ``SELECT orders_seq.NEXTVAL + 1 FROM DUAL`` and advance the sequence, again
+#: on every cache expiry, for a dataset editor holding neither SQL Lab nor a
+#: DML grant. Reading one is a write however the parser classifies it.
+#:
+#: The function spelling (``nextval('s')`` on PostgreSQL) is a different shape
+#: and is caught as a function; this is only about the suffix form.
+SEQUENCE_PSEUDO_COLUMNS = frozenset({"nextval", "currval"})
+
+#: The same thing written as a call.
+#:
+#: Only the suffix form parses as a column; `nextval('s')` on PostgreSQL and
+#: DuckDB, `NEXTVAL(s)`/`SETVAL(s, 1)` on MySQL and MariaDB, and SQL Server's
+#: `NEXT VALUE FOR s` all parse as functions. `SQLStatement.is_mutating` walks
+#: function names on PostgreSQL alone -- deliberately, since the same names are
+#: read-only elsewhere -- so every other engine let these through.
+#:
+#: Matched on the name whatever the engine, because advancing a sequence is a
+#: write wherever it happens and a transform has no reason to call one.
+SEQUENCE_FUNCTIONS = frozenset(
+ {"nextval", "setval", "next_value_for", "nextvalfor", "prevval", "lastval"}
+)
+
+
+def references_sequence(statement: SQLStatement) -> bool:
+ """Whether the statement reads or advances a sequence.
+
+ Both spellings: the pseudo-column suffix, which parses as a column (see
+ `SEQUENCE_PSEUDO_COLUMNS`), and the call, which parses as a function (see
+ `SEQUENCE_FUNCTIONS`).
+
+ Answered on the parse rather than on raw text, because position is what
+ makes it the construct: a column or alias merely *called* ``nextval`` is
+ an ordinary column, and a string literal holding the word is text.
+ """
+ return bool(
+ statement.get_column_names() & SEQUENCE_PSEUDO_COLUMNS
+ or statement.get_disallowed_functions(set(SEQUENCE_FUNCTIONS))
+ )
+
+
+def contains_jinja(transform: str | None) -> bool:
+ """
+ Whether the transform contains a balanced Jinja block.
+
+ A block is an opening delimiter followed, anywhere later, by its closing
+ one -- the same thing ``{{.*?}}`` and its two siblings match under
+ ``re.DOTALL``. Scanned with `str.find` rather than that pattern, because a
+ lazy match retried from every opening delimiter is quadratic in a run of
+ them, and this runs on stored transforms with no length bound of its own:
+ `is_transform_active` reads whatever the column holds. The earliest opening
+ delimiter is the only one worth trying, since any closing delimiter after a
+ later one is also after it.
+ """
+ if not transform:
+ return False
+ for opening, closing in JINJA_BLOCK_DELIMITERS:
+ start = transform.find(opening)
+ if start != -1 and transform.find(closing, start + len(opening)) != -1:
+ return True
+ return False
+
+
+def parse_skeleton(transform: str, standin: str = _PARSE_STANDIN) -> str:
+ """
+ The transform with ``:value`` substituted out, ready for a SQL parser.
+
+ ``sanitize_clause`` / sqlglot choke on a bare ``:value`` on most dialects,
+ so the placeholder is swapped for a benign literal first -- the same trick
+ ``validate_stored_expression`` uses for Jinja blocks.
+
+ :param standin: what to substitute. `placeholder_is_executable` passes
+ `_PLACEHOLDER_STANDIN` to find out where the placeholder landed.
+ """
+ # Substituted through a function so `standin` is taken literally. As a
+ # replacement *string* `re.sub` would read backslashes in it as escapes,
+ # and `build_probe_sql` passes rendered SQL here: a filter value containing
+ # `\n` would probe a newline instead of the two characters the predicate
+ # compares, and one containing `\1` would raise outright.
+ return VALUE_PLACEHOLDER_RE.sub(lambda _: standin, transform)
+
+
+#: Prefix the transform is wrapped in before parsing. Its length is subtracted
+#: from any reported column so positions refer to what the owner actually
typed.
+_SELECT_PREFIX = "SELECT "
+
+
+def _parse_skeleton(
+ transform: str, engine: str, standin: str = _PARSE_STANDIN
+) -> SQLStatement | None:
+ """
+ Parse ``SELECT <transform>`` with the placeholder substituted out.
+
+ Returns ``None`` when the transform does not parse.
+ """
+ try:
+ return SQLStatement(
+ f"{_SELECT_PREFIX}{parse_skeleton(transform, standin)}", engine
+ )
+ except SupersetParseError:
+ return None
+
+
+def parse_error_detail(transform: str, engine: str) -> str | None:
+ """
+ Where the parser gave up on the transform.
+
+ Returns ``None`` when it parses, or when the parser offered no position.
+ Note that sqlglot parses unknown functions happily -- a misspelled function
+ name is not a parse error, it is an engine error, and surfaces only when
the
+ transform is evaluated.
+
+ The parser's own ``highlight`` is deliberately dropped: it would name the
+ ``NULL`` we substituted for ``:value``, which is not a token the owner
typed.
+ """
+ try:
+ SQLStatement(f"{_SELECT_PREFIX}{parse_skeleton(transform)}", engine)
+ except SupersetParseError as ex:
+ column = (ex.error.extra or {}).get("column")
+ if not isinstance(column, int):
+ return None
+ return str(
+ _(
+ "syntax error at position %(position)d.",
+ position=_position_in_transform(transform, column),
+ )
+ )
+ return None
+
+
+def _position_in_transform(transform: str, parsed_column: int) -> int:
+ """
+ Map a column in the parsed skeleton back to the transform as typed.
+
+ Two substitutions stand between them: the ``SELECT`` prefix, and every
+ ``:value`` that became a shorter ``NULL``. Without unwinding both, a
+ reported position drifts left by two characters per placeholder ahead of it
+ -- which is worst exactly where transforms usually break, at the end.
+ """
+ position = max(parsed_column - len(_SELECT_PREFIX), 0)
+ shift = len(":value") - len(_PARSE_STANDIN)
+ preceding = sum(
+ 1
+ for index, match in enumerate(VALUE_PLACEHOLDER_RE.finditer(transform))
+ if match.start() - index * shift < position
+ )
+ return position + preceding * shift
+
+
+def placeholder_is_executable(transform: str | None, engine: str) -> bool:
+ """
+ Whether every ``:value`` sits where the engine will evaluate it.
+
+ `contains_value_placeholder` is a regex over raw text, and `parse_skeleton`
+ substitutes before parsing, so neither notices a placeholder that is not in
+ an executable position. Two shapes reach the probe that way, and both are
+ worse than the inactive mapping a malformed transform earns:
+
+ ``':value'`` -- the placeholder inside a string literal. `build_probe_sql`
+ binds it anyway, because SQLAlchemy's own ``text()`` scan is no more
+ literal-aware than the regex, and the dialect then renders the bind
+ *including its own quotes* in the middle of the owner's quotes. A value of
+ ``" || (SELECT secret FROM vault LIMIT 1) || "`` closes the literal and
+ compiles to a working sub-query -- the very read primitive
+ `stored_expression_error` refuses when it is written openly.
+
+ ``1 -- :value`` -- the placeholder inside a comment. The probe's selections
+ are joined on one line, so the comment swallows its own ``AS v0`` alias and
+ everything after it; a single-value probe still returns one column, the
+ constant is accepted as the transform's result, and the mirror then emits
+ ``partition_col = <constant>`` for every filter value. That is wrong rows,
+ not lost pruning.
+
+ Answered structurally: substitute an identifier rather than a keyword and
+ count the column references it produced. A literal holds no column
+ reference and a comment is not parsed at all, so either case comes back
+ short of the number of placeholders the owner wrote.
+
+ Which is why a transform naming the stand-in itself is refused outright.
The
+ count is the whole gate, and a hand-written occurrence pays the difference:
+ ``concat(superset_pfm_value_standin, ':value')`` has one placeholder,
inside
+ a literal that contributes nothing, and one bare reference the owner wrote
--
+ so the counts match and the gate passes a placeholder the engine will never
+ evaluate. The probe then renders the bound value inside the owner's quotes,
+ where a value closing the literal can alias a column of any table the
+ connection can read into the stand-in's name and have the probe hand it
back
+ through the preview. There is no legitimate transform naming this
identifier,
+ so refusing it costs nothing and makes the count mean what it claims.
+ """
+ if not transform:
+ return False
+ if _PLACEHOLDER_STANDIN in transform.lower():
+ # Lowercased on both sides because `count_bare_column_references` is
+ # case-insensitive too: a dialect may normalize an unquoted identifier,
+ # so `SUPERSET_PFM_VALUE_STANDIN` would otherwise balance the count
+ # while slipping past a case-sensitive check here.
+ return False
+ expected = len(VALUE_PLACEHOLDER_RE.findall(transform))
+ if not expected:
+ return False
+ statement = _parse_skeleton(transform, engine, _PLACEHOLDER_STANDIN)
+ if statement is None:
+ return False
+ return statement.count_bare_column_references(_PLACEHOLDER_STANDIN) ==
expected
+
+
+def is_parseable(transform: str | None, engine: str) -> bool:
+ """
+ Whether the transform parses as a single select expression.
+
+ "Single" is the load-bearing word. `SELECT lower(:value), 'x'` parses just
+ as happily as `SELECT lower(:value)`, but it returns two columns per input
+ value, and the probe reads one column per input -- so an `IN` filter would
+ get a predicate built from the wrong halves of the wrong rows. Rejecting
the
+ list here is what lets the probe trust its own column count.
+ """
+ if not transform or not transform.strip():
+ return False
+ statement = _parse_skeleton(transform, engine)
+ return statement is not None and statement.count_select_expressions() == 1
+
+
+def is_bare_expression(transform: str | None, engine: str) -> bool:
+ """
+ Whether the transform is a scalar expression and nothing more.
+
+ `is_parseable` is not enough, because it counts only the projection.
+ ``secret || :value FROM vault`` holds exactly one select expression, so it
+ parses as "a single expression" -- and `build_probe_sql` then emits
+ ``SELECT secret || 'us' AS v0``, where its own alias is read as a table
+ alias on the FROM clause the transform smuggled in. The probe reads a
+ column the owner was never granted and hands it back through the predicate
+ the preview panel renders.
+
+ A transform is a scalar function of ``:value`` by definition -- the whole
+ feature rests on ``partition_col = T(mapped_col)``, which only type-checks
+ for scalar ``T`` -- so there is no legitimate transform with a clause of
+ its own, and none with a sub-query either.
+ """
+ if not transform or not transform.strip():
+ return False
+ statement = _parse_skeleton(transform, engine)
+ return (
+ statement is not None
+ and statement.is_bare_select_expression()
+ and not statement.has_subquery()
+ )
+
+
+def is_unfinished(transform: str | None, engine: str) -> bool:
+ """
+ Whether the transform is not SQL yet, as opposed to the wrong SQL.
+
+ The distinction matters because the two deserve opposite treatment. A
+ half-typed ``unix_timestamp(:value`` is what a text input produces on the
+ way to something valid: a PUT stores it and reports the mapping inactive,
+ so discarding it would mean an export could not round-trip the dataset it
+ came from. ``unix_timestamp(:value); DROP TABLE t`` is not on the way to
+ anything, and has to be refused wherever it is offered.
+
+ Both fail `is_parseable`, and both fail to parse as a single *statement* --
+ so neither of those tells them apart. Parsing as a *script* does: the
+ multi-statement form is two valid statements, while unfinished text is no
+ statement at all.
+ """
+ if not transform or not transform.strip():
+ return False
+ try:
+ SQLScript(f"{_SELECT_PREFIX}{parse_skeleton(transform)}", engine)
+ except SupersetParseError:
+ return True
+ return False
+
+
+def find_non_deterministic_functions(transform: str, engine: str) -> set[str]:
+ """
+ Names of non-deterministic functions the transform calls.
+
+ ``UNIX_TIMESTAMP`` is only reported in its zero-argument form, which means
+ "now" on Hive and Impala; the one-argument form is the canonical temporal
+ transform and stays allowed.
+
+ Three spellings have to be looked for, because one name reaches the parse
+ three ways: as a function call, as a zero-argument call a dialect resolves
+ itself, and -- for the datetime keywords -- as a bare word that parses as a
+ column reference.
+ """
+ statement = _parse_skeleton(transform, engine)
+ if statement is None:
+ return set()
+
+ found = {
+ name
+ for name in NON_DETERMINISTIC_FUNCTIONS
+ if statement.check_functions_present({name})
+ }
+ # The parenthesis-free spellings, which parse as columns rather than
+ # functions and so are invisible to the walk above. See
+ # `BARE_WALL_CLOCK_KEYWORDS`.
+ found |= {
+ name.upper() for name in BARE_WALL_CLOCK_KEYWORDS &
statement.get_column_names()
+ }
+ return found | _find_niladic_calls(statement)
+
+
+def _find_niladic_calls(statement: SQLStatement) -> set[str]:
+ """
+ Names from ``NON_DETERMINISTIC_WHEN_NILADIC`` called with no arguments.
+
+ Note some dialects resolve the zero-argument form themselves -- Hive parses
+ ``unix_timestamp()`` straight to ``CURRENT_TIMESTAMP`` -- in which case the
+ name-based check above has already caught it. This is the backstop for the
+ dialects that do not.
+ """
+ return NON_DETERMINISTIC_WHEN_NILADIC & statement.get_niladic_functions()
+
+
+def resolve_partition_mapping(datasource: SqlaTable) -> PartitionMapping |
None:
+ """
+ Resolve the dataset's mapping, or ``None`` when nothing may be mirrored.
+
+ Every bail-out here is defensive as well as functional: save-time
validation
+ rejects most of these, but rows predating the validation can still violate
+ the invariants, and a column sync can invalidate a mapping that was fine
+ when it was written.
+
+ The transform gate is `is_transform_active`, the same function the Explore
+ indicator reads, which is `validate_transform` with the messages discarded.
+ Anything narrower here would be a second, weaker statement of the same
rule:
+ a transform calling `now()` that reached storage without passing
+ `UpdateDatasetCommand` -- through import, or through a bundle written by
hand
+ -- would be reported inactive by the editor and still mirrored by this
+ function, freezing a snapshot of probe time into the predicate with nothing
+ on screen to say so.
+ """
+ if not feature_flag_manager.is_feature_enabled(FEATURE_FLAG):
+ return None
+
+ partition_column = getattr(datasource, "partition_column", None)
+ if not partition_column:
+ return None
+
+ columns_by_name = {column.column_name: column for column in
datasource.columns}
+ if partition_column not in columns_by_name:
+ # The partition column was dropped by a column sync or at the source.
+ return None
+
+ mapped_column_name = (
+ getattr(datasource, "partition_mapped_column", None) or
datasource.main_dttm_col
+ )
+ if not mapped_column_name or mapped_column_name not in columns_by_name:
+ return None
+
+ if mapped_column_name == partition_column:
+ # Self-mapping: the mirrored predicate would duplicate the original.
+ return None
+
+ mapped_column = columns_by_name[mapped_column_name]
+ transform = getattr(mapped_column, "partition_value_transform", None)
+ if not is_transform_active(transform, datasource.database.backend):
+ return None
+
+ if has_active_advanced_data_type(mapped_column):
+ # `translate_filter` builds its own predicate shape from *translated*
+ # values, so the `(operator, value)` pair the operator matrix reasons
+ # about does not exist and mirroring would apply the wrong values.
+ return None
+
+ return PartitionMapping(
+ partition_column=str(partition_column),
+ mapped_column=str(mapped_column_name),
+ value_transform=cast(str, transform),
+ is_monotonic=bool(
+ getattr(mapped_column, "partition_transform_is_monotonic", False)
+ ),
+ equality_is_safe=equality_mirrors_safely(
+ mapped_column, datasource.database.db_engine_spec
+ ),
+ )
+
+
+def has_active_advanced_data_type(column: TableColumn) -> bool:
+ """
+ Whether the column's advanced data type is configured and switched on.
+
+ Such a column is never mirrored: ``translate_filter`` builds its own
+ predicate shape from translated values, so the ``(operator, value)`` pair
+ the operator matrix reasons about does not exist.
+ """
+ advanced_data_type = getattr(column, "advanced_data_type", None)
+ if not advanced_data_type:
+ return False
+ if not
feature_flag_manager.is_feature_enabled("ENABLE_ADVANCED_DATA_TYPES"):
+ return False
+ return advanced_data_type in app.config.get("ADVANCED_DATA_TYPES", {})
+
+
+def _denylist_engine_key(database: "Database") -> str:
+ """
+ The name ``DISALLOWED_SQL_*`` is keyed by for this database.
+
+ The engine spec's own ``engine`` first, because that is what every other
+ denylist gate uses (`_raise_for_disallowed_sql`, `sql_lab`) and what an
+ operator writing the config reads in the documentation; a spec covering
+ several SQLAlchemy backends through ``engine_aliases`` reports the one
+ canonical name under which its entry is written.
+
+ Falling back to the URL's backend, because resolving the spec loads the
+ SQLAlchemy dialect entrypoint, which imports the driver package. On a
+ deployment missing an optional driver that raises rather than merely being
+ absent, asking for the spec here would turn a dataset import into a hard
+ failure -- and for every engine without aliases the two names are the same
+ string anyway.
+ """
+ try:
+ return database.db_engine_spec.engine
+ except Exception: # pylint: disable=broad-except # noqa: BLE001
+ return database.backend
+
+
+def stored_expression_error( # noqa: C901
+ database: "Database",
+ catalog: str | None,
+ schema: str | None,
+ transform: str,
+) -> str | None:
+ """
+ Why this transform may not be stored or run, if there is a reason.
+
+ Stricter than the policy a general stored expression goes through, because
+ a value transform is a narrower thing: `build_probe_sql` binds only
+ `:value` and splices the rest of the transform in as SQL text, which the
+ engine then executes, so an ungated transform is arbitrary SQL. A dataset
+ editor without SQL Lab could store `(SELECT secret FROM protected_table
+ LIMIT 1) || :value`, or `secret || :value FROM protected_table`, and read
+ the answer back out of the emitted predicate the preview panel renders.
+
+ So the transform must be a bare scalar expression: no clause of its own and
+ no sub-query, whatever `ALLOW_ADHOC_SUBQUERY` says. That is not a
+ restriction the feature pays for -- it rests on
+ ``partition_col = T(mapped_col)``, which only type-checks for scalar ``T``
+ -- and it is what makes the table denylist and the RLS rewrite moot here,
+ since neither has a table reference left to govern.
+
+ And it must be a *read*. Shape is a separate question from effect: a bare
+ scalar expression can still write, so `SQLStatement.is_mutating` is asked
+ too -- the same question SQL Lab and the chart executor ask before letting
+ SQL run. See the gate itself for what that reaches and what it does not.
+
+ Returns the engine-agnostic reason as a string rather than raising,
+ because its four callers disagree about what to do with it: the preview
+ reports it at the field, a PUT and the legacy datasource save refuse the
+ write, the importer drops the transform and keeps the dataset, and the
+ probe simply declines to run. Raising would make three of those four
+ write a `try` around a question.
+
+ Imported inside the function rather than at module scope:
+ `connectors.sqla.models` imports this module, so the dependency only runs
+ one way at import time.
+ """
+ from superset.connectors.sqla.models import ( # pylint:
disable=import-outside-toplevel,cyclic-import
+ validate_stored_expression,
+ )
+
+ # Ahead of the parse, both because it is the cheaper question and because
+ # the parse is the cost the bound exists to contain.
+ if len(transform) > MAX_TRANSFORM_LENGTH:
+ return str(
+ _(
+ "A partition value transform cannot be longer than "
+ "%(limit)d characters.",
+ limit=MAX_TRANSFORM_LENGTH,
+ )
+ )
+
+ # Also ahead of the parse, and for a stronger reason than cost: every gate
+ # below reasons about the parse tree, and this is the one construct that
+ # makes the parse tree describe a different statement from the one the
+ # engine runs. Checked here as well as in `validate_transform` because this
+ # is the door a row written by an earlier release still comes through.
+ if contains_executable_comment(transform):
+ return str(
+ _(
+ "A partition value transform cannot contain a MySQL "
+ "executable comment, which the database executes and every "
+ "validator reads as a comment."
+ )
+ )
+
+ if contains_unicode_escaped_identifier(transform):
+ return str(
+ _(
+ "A partition value transform cannot name anything through a "
+ 'U&"..." escape sequence, which the database decodes and '
+ "every validator reads literally."
+ )
+ )
+
+ # Same door, same reason: the name the denylist below would match is not
+ # the name the engine resolves. See `UNICODE_ESCAPED_IDENTIFIER_RE`.
+ statement = _parse_skeleton(transform, database.backend)
+ if statement is None:
+ return str(
+ _("A partition value transform must parse as a single SQL
expression.")
+ )
+
+ # The shape gate again, even though `validate_transform` blocks the same
+ # thing at save time. This is the last door before the transform becomes
SQL
+ # an engine runs, and the only door a row written by an earlier release --
+ # or by an importer that ran with the feature flag off -- still passes
+ # through.
+ if not statement.is_bare_select_expression():
+ return str(
+ _(
+ "A partition value transform must be a single SQL expression, "
+ "with no FROM, WHERE or other clause."
+ )
+ )
+
+ # Unconditionally, not under `ALLOW_ADHOC_SUBQUERY`. A transform is a
scalar
+ # function of `:value`, so a sub-query in one has no legitimate use, and it
+ # is a read primitive whose answer the preview panel renders back to its
+ # caller. Refusing it is also what lets this function skip the table
+ # denylist and the row-level-security rewrite: with no FROM clause and no
+ # sub-query there is no table reference for either to govern.
+ if statement.has_subquery():
+ return str(_("A partition value transform cannot contain a
sub-query."))
+
+ # The read-only gate, which nothing above implies. The shape gates ask what
+ # the transform *selects*; this asks what evaluating it *does*, and a bare
+ # scalar expression can still write. `nextval(:value)` on PostgreSQL
+ # advances a sequence: one function call, no clause, no sub-query, and not
+ # in the default `DISALLOWED_SQL_FUNCTIONS` either -- so every gate above
+ # passes it and the probe then runs it. `setval` is the same shape, and
+ # `exp.Execute` and the opaque-`exp.Command` forms arrive the same way.
+ #
+ # The large-object writers (`lo_export`, `lowrite`, `lo_from_bytea`, ...)
+ # are caught here too, and the shipped denylist happens to name them as
+ # well -- but that is config an operator can replace, while this is not.
+ #
+ # `is_mutating` is the same question SQL Lab, `get_virtual_table_metadata`
+ # and the chart executor ask before letting SQL run, so a transform is held
+ # to the bar the rest of Superset already sets rather than to one invented
+ # here. Unconditional rather than gated on `Database.allow_dml`: a
transform
+ # is a scalar function of `:value` by definition, so there is no legitimate
+ # mutating one, and the probe runs on a cache schedule nobody chose -- a
+ # write would repeat every time the entry expired.
+ #
+ # It bears saying what this does not reach. A user-defined function whose
+ # body writes is a plain call no parser can tell from `lower(:value)`, and
+ # `is_mutating`'s function-name walk is PostgreSQL-only by design, since
the
+ # same names are read-only elsewhere. Neither residual is specific to this
+ # feature -- a dataset editor can already have the engine evaluate an
+ # arbitrary expression through a calculated column or a virtual dataset's
+ # SQL -- and closing them means authorizing the preview against the
+ # database, not parsing harder.
+ if statement.is_mutating():
+ return str(
+ _(
+ "A partition value transform cannot change data. It is "
+ "evaluated against the database to check that it mirrors, so "
+ "it has to be a read."
+ )
+ )
+
+ # Not reached by the walk above, which is why it is its own gate: a
+ # sequence pseudo-column is a *column* to the parser and a write to the
+ # engine. See `SEQUENCE_PSEUDO_COLUMNS`.
+ if references_sequence(statement):
+ return str(
+ _(
+ "A partition value transform cannot read a sequence. "
+ "NEXTVAL advances the sequence every time it is evaluated, "
+ "and the transform is evaluated on a cache schedule."
+ )
+ )
+
+ # The shape gates above read the transform with `:value` replaced by the
+ # `NULL` keyword, which leaves no trace of where the placeholder was -- so
+ # none of them can see a placeholder that is not in an executable position.
+ # Checked here as well as in `validate_transform` because this is the door
+ # a row written by an earlier release still passes through, and because
+ # the escape only completes once a filter value is bound.
+ #
+ # Guarded on the placeholder being present at all: a transform without one
+ # is inert rather than refused (`validate_transform` reports it as Tier 2),
+ # and refusing it here would make this gate stricter than the PUT's.
+ if contains_value_placeholder(transform) and not placeholder_is_executable(
+ transform, database.backend
+ ):
+ return str(
+ _(
+ "A partition value transform must use the :value placeholder "
+ "where the engine will evaluate it, not inside a string "
+ "literal or a comment."
+ )
+ )
+
+ denied = app.config["DISALLOWED_SQL_FUNCTIONS"].get(
+ _denylist_engine_key(database), set()
+ )
+ if denied and (found := statement.get_disallowed_functions(denied)):
+ return str(
+ _(
+ "A partition value transform cannot call %(functions)s.",
+ functions=", ".join(sorted(found)),
+ )
+ )
+
+ # Kept as the tail call rather than replaced: this is where
`sanitize_clause`
+ # runs. Its own sub-query branch returns rewritten, RLS-injected SQL that
+ # this function has no way to propagate -- but that branch is unreachable
+ # from here now, because a transform containing a sub-query was refused
+ # above, so discarding the return value is correct rather than a leak.
+ try:
+ validate_stored_expression(database, catalog, schema,
parse_skeleton(transform))
+ except SupersetSecurityException as ex:
+ return str(ex.error.message)
+ except QueryClauseValidationException as ex:
+ return str(ex.message)
+ return None
+
+
+@dataclass(frozen=True)
+class RawProbeValue:
+ """
+ A probe value that is already SQL text rather than a bindable scalar.
+
+ Almost every filter value is a Python scalar, which `build_probe_sql` binds
+ and lets the dialect render. An array column's value is not: the predicate
+ it mirrors compares an engine array literal -- ``array('a', 'b')`` on
+ ClickHouse -- which `BaseEngineSpec.array_literal` returns as a SQLAlchemy
+ expression, and an expression cannot be the value of a bind parameter.
+
+ Frozen, and holding text rather than the expression, for two reasons
+ besides immutability: `_probe_cache_key` keys on ``repr`` of each value,
and
+ an expression's ``repr`` carries its memory address -- so caching the probe
+ would key every call differently. `_hashable` needs it hashable too.
+
+ Build one with `raw_probe_value`, which renders the expression through the
+ same literal compilation the bound path uses.
+ """
+
+ sql: str
+
+
+def raw_probe_value(database: "Database", element: Any) -> RawProbeValue:
+ """
+ Freeze an engine-built expression into probe-ready SQL text.
+
+ The text is produced entirely by SQLAlchemy and the engine spec from values
+ that have already been coerced, so no caller-supplied text reaches the
+ probe uninspected. Rendering is not what makes that true: a string element
+ is checked by `literal_round_trips` before it is rendered -- the dialect's
+ literal processor and the engine's lexer do not always agree about what a
+ rendered literal says -- and `probe_sql_is_evaluable` re-reads the finished
+ query, which is what bounds the splice.
+
+ :param database: the database whose dialect renders the literal
+ :param element: a SQLAlchemy expression, e.g. from ``array_literal``
+ :return: the rendered expression, ready to stand in for ``:value``
+ """
+ return RawProbeValue(_compile_literal(element, _dialect_for(database)))
+
+
+def normalize_mixed_numbers(values: Sequence[Any]) -> list[Any]:
+ """
+ One numeric type across ``values``, so a bind cannot be inferred wrongly.
+
+ SQLAlchemy infers an ``IN`` bind's type from the first element it is given.
+ A list mixing an int with a float therefore binds as integer and truncates
+ every later float: ``[33, 29.02]`` emits ``IN (33, 29)`` and drops the row
+ matching ``29.02``.
+
+ Applied on both sides of the probe, which is why it lives here rather than
+ inline at either: the filter values collected for mirroring have to match
+ the ones the real predicate binds (see #33206), and the probe *results*
+ bound against the partition column have the same problem one step later.
+
+ Leaves the list alone when nothing in it is a float, so an exact integer
+ key above 2^53 is not rounded for no reason.
+
+ :param values: the values about to be bound
+ :return: the values, with every number widened to ``float`` if any was
+ """
+ if not any(isinstance(value, float) for value in values):
+ return list(values)
+ return [
+ float(value) if isinstance(value, (int, float)) else value for value
in values
+ ]
+
+
+def _placeholder_is_bindable(transform: str) -> bool:
+ """
+ Whether SQLAlchemy's ``text()`` can see ``:value`` as a bound parameter.
+
+ `VALUE_PLACEHOLDER_RE` is ``:value\b``, which matches the placeholder in a
+ Postgres cast such as ``:value::bigint``. SQLAlchemy's own bind scan is
+ ``(?<![:\\w$]):([\\w$]+)(?![:\\w$])`` -- note the trailing exclusion -- so
a
+ following colon stops it: ``text(":value::bigint")`` reports a parameter
+ named ``valu``, and ``.bindparams(bindparam("value"))`` then raises
+ ``ArgumentError``.
+
+ `_probe` swallows that, so the only symptom was a perfectly valid transform
+ whose mapping silently never pruned, and a preview reporting an engine
+ failure for SQL that was never sent. Every write-side gate passes the
+ transform: it parses, it is a bare expression, and the placeholder *is* in
+ an executable position.
+
+ Answered by attempting the bind itself rather than by pattern-matching
+ ``::`` or reading ``text()``'s private parameter map, so this cannot
+ disagree with what `build_probe_sql` is about to do -- on any dialect, or
on
+ a SQLAlchemy whose scan changes.
+ """
+ try:
+ sa.text(transform).bindparams(sa.bindparam("value", value=None))
+ except Exception: # pylint: disable=broad-except # noqa: BLE001
+ return False
+ return True
+
+
+def escape_foreign_colons(transform: str) -> str:
+ """
+ ``transform`` with every colon but the ``:value`` placeholder escaped.
+
+ `sqlalchemy.text` reads any ``:word`` as a bind parameter, including one
+ inside a string literal, and an unbound parameter renders as ``NULL``
+ under literal binds rather than raising. So ``:value || \':suffix\'``
+ compiled to ``'us' || 'NULL'``: the mirror asked for a partition value no
+ row holds and the chart dropped rows, with no error for `_probe` to
+ swallow and nothing on screen to say so.
+
+ Escaped rather than refused, because a colon in a literal is ordinary --
+ ``concat(:value, \':\', region)`` builds a composite key -- and the
+ placeholder is the only colon this module means to interpret. `text()`
+ reads ``\\:`` as a literal colon.
+
+ Only the bound path needs this. A `RawProbeValue` or an unbindable
+ placeholder is substituted as text by `parse_skeleton`, which never hands
+ the transform to `text()` at all.
+ """
+ pieces: list[str] = []
+ cursor = 0
+ for match in VALUE_PLACEHOLDER_RE.finditer(transform):
+ pieces.append(transform[cursor : match.start()].replace(":", r"\:"))
+ pieces.append(match.group(0))
+ cursor = match.end()
+ pieces.append(transform[cursor:].replace(":", r"\:"))
+ return "".join(pieces)
+
+
+def literal_round_trips(value: Any, dialect: Dialect | None, engine: str) ->
bool:
+ """
+ Whether the engine reads a rendered ``value`` back as that same value.
+
+ The probe runs with no bound parameters, so every value reaches the engine
+ as literal text the driver wrote (see `build_probe_sql`). Whether that text
+ says what the value says is a question about two independent spellings: the
+ driver's escaping, and the engine's lexer. SQLAlchemy's default renderer
+ doubles apostrophes and passes backslashes through; Hive and Spark honour
+ the backslash and not the doubling, so ``'O''Brien'`` is read there as two
+ adjacent literals -- the transform is evaluated at ``OBrien``, and the
+ mirror asks for a partition key that holds none of the rows the filter
+ keeps. The same gap in the other direction lets a value close its own quote
+ and have the rest of it read as SQL.
+
+ Escaping is not the repair. Whether a backslash introduces an escape is a
+ per-session server setting -- ``standard_conforming_strings`` on Postgres,
+ ``NO_BACKSLASH_ESCAPES`` on MySQL, ``escapedStringLiterals`` on Spark --
and
+ nothing in the engine specs exposes it. SQLAlchemy reads it off the server
+ into ``_backslash_escapes`` during ``initialize(connection)``, which the
+ probe's dialect never reaches: `_dialect_for` asks the ``Database`` for a
+ dialect, not for a connection, so Postgres renders ``a\\b`` as
+ ``'a\\\\b'`` and a server with the standard setting reads four
+ characters. An engine-spec flag would have to be defaulted, and either
+ default is wrong for a dozen engines: one leaves the hole open, the other
+ corrupts the probed value.
+
+ So the premise is verified rather than declared, the way
+ `probe_sql_is_evaluable` verifies the finished statement. A value that does
+ not survive the round trip is not mirrored, which costs the query its
+ pruning and nothing else.
+
+ The short-circuit is a proof, not a guess, and it matters for cost: a
+ 200-member ``IN`` list would otherwise parse 200 times on the chart path.
+ If the renderer emitted the value between two quotes and changed nothing in
+ it, and the value carries neither a quote nor a backslash, then no lexer in
+ play can read it as anything but itself. Both exclusions are load-bearing:
+ on Hive ``a\\b`` renders verbatim and reads as ``a`` followed by a
+ backspace.
+
+ :param value: a filter value about to be rendered into the probe
+ :param dialect: the dialect that will render it, as `_dialect_for` reports
+ :param engine: ``database.backend``, whose lexer reads the result
+ :return: whether the two agree about what the literal says
+ """
+ if isinstance(value, RawProbeValue):
+ # Already SQL, with no single value for a parse to be compared against:
+ # its elements are checked before they are rendered, by
+ # `ExploreMixin._array_mirror_probe_value`. A backslash surviving into
+ # the finished text is refused here all the same, as the backstop for a
+ # renderer this module does not own.
+ return "\\" not in value.sql
+ if not isinstance(value, str):
+ # Numbers and instants are not written between delimiters, so there is
+ # no escaping for the two sides to disagree about.
+ return True
+
+ rendered = _compile_literal(sa.literal(value), dialect)
+ if rendered == f"'{value}'" and "'" not in value and "\\" not in value:
+ return True
+
+ try:
+ return (
+ SQLStatement(f"SELECT {rendered}",
engine).get_select_literal_value()
+ == value
+ )
+ except SupersetParseError:
+ # A rendered literal the engine's own dialect will not parse is the
+ # strongest form of disagreement there is.
+ return False
+
+
+def value_round_trips(database: Database, value: Any) -> bool:
+ """
+ `literal_round_trips` for a caller holding a database, not a dialect.
+
+ Which renderer and which lexer apply is this module's business, so the two
+ callers outside it -- the chart path's own gate in
+ `ExploreMixin.mirror_probe_request` and the mapping summary Explore reads
+ -- ask in these terms and stay out of it.
+
+ :param database: the database whose driver renders and whose engine reads
+ :param value: a filter value about to be rendered into the probe
+ :return: whether the two agree about what the literal says
+ """
+ return literal_round_trips(value, _dialect_for(database), database.backend)
+
+
+def build_probe_sql(
+ transform: str,
+ values: list[Any],
+ dialect: Dialect | None = None,
+ from_suffix: str = "",
+) -> str:
+ """
+ Compile a single ``SELECT`` that evaluates the transform at every value.
+
+ Values are attacker-controlled (a Gamma user picks filter values), so they
+ are bound as parameters and rendered by the dialect's own literal processor
+ rather than interpolated into the SQL text. That is not itself a boundary:
+ the processor's escaping is not always the escaping the engine honours, and
+ a value can close its own quote through the gap. The boundary is
+ `literal_round_trips` on the way in -- which callers must have run, like
+ `stored_expression_error` below -- and `probe_sql_is_evaluable` on the way
+ out.
+
+ ``from_suffix`` comes from the engine spec's
``select_without_from_suffix``.
+ A ``SELECT`` with no ``FROM`` is not universal SQL: Oracle and Db2 need a
+ one-row table to select from, and without it every probe on those engines
+ raises -- which `_run_probe` swallows, so the only symptom is a correctly
+ configured mapping that silently never prunes.
+
+ Note this deliberately does *not* go through ``BaseEngineSpec``'s text
+ helper, which escapes ``:`` on every engine but Athena and would destroy
the
+ ``:value`` placeholder before it can be bound.
+
+ Callers must have run `stored_expression_error` first. The ``AS v{index}``
+ alias and ``from_suffix`` are only safe on a transform with no clause of
its
+ own; on one carrying its own FROM they attach to that instead.
+ """
+ bindable = _placeholder_is_bindable(transform)
+ selections = []
+ for index, value in enumerate(values):
+ if isinstance(value, RawProbeValue):
+ # Already SQL, so substituted rather than bound -- and deliberately
+ # not run through `_compile_literal`, which has nothing to compile
+ # and would undouble percent signs the owner typed on purpose.
+ rendered = parse_skeleton(transform, value.sql)
+ elif bindable:
+ # Every other colon escaped first: `text()` would read one inside a
+ # string literal as a second bind parameter and render it `NULL`.
+ # See `escape_foreign_colons`.
+ clause = sa.text(escape_foreign_colons(transform)).bindparams(
+ sa.bindparam("value", value=value)
+ )
+ rendered = _compile_literal(clause, dialect)
+ else:
+ # `text()` cannot see the placeholder (see
+ # `_placeholder_is_bindable`), so the value is rendered by the
+ # dialect's own literal processor first and substituted as SQL
+ # text. The same two steps in the other order: binding exists to
+ # get the value through that processor, and `_compile_literal`
+ # inlines the result either way, so this is the same string by a
+ # different route -- not a loosening of the "never interpolate a
+ # raw value" rule. `parse_skeleton` substitutes literally, so the
+ # rendered literal arrives here exactly as it was rendered, which
+ # is what makes `literal_round_trips`' verdict on it good for this
+ # branch as much as for the bound one.
+ rendered = parse_skeleton(
+ transform, _compile_literal(sa.literal(value), dialect)
+ )
+ selections.append(f"{rendered} AS v{index}")
+ return "SELECT " + ", ".join(selections) + from_suffix
+
+
+def probe_sql_is_evaluable(
+ sql: str,
+ engine: str,
+ expected: int,
+ from_suffix: str = "",
+) -> bool:
+ """
+ Whether the compiled probe is still the query `build_probe_sql` intended.
+
+ Every write-side gate reads the transform with ``:value`` standing in for a
+ value. The escape this guards against only completes once a *real* value is
+ rendered in its place, so it is invisible until this point -- and the
values
+ are supplied by whoever is filtering a chart, not only by the owner who
+ wrote the transform.
+
+ Five things have to hold, and all five are about the probe still being
+ readable rather than about taste:
+
+ * One statement. A value that closes the expression and starts another
+ would otherwise run both.
+ * No sub-query. A placeholder inside a string literal lets a value close
+ the quote and concatenate one; `stored_expression_error` refuses a
+ sub-query written openly, and this refuses the same thing assembled.
+ * Exactly ``expected`` projections, aliased ``v0`` upward. A comment
+ swallows the rest of its line including its own alias, and the engine
+ still answers with a column -- so the count alone does not notice.
+ Checking the aliases is what makes a missing one visible.
+ * No clause this function did not build, and a ``FROM`` only where
+ ``select_without_from_suffix`` asked for one -- the engine's own, not
+ merely some table. A rendered value can close the projection and append a
+ ``FROM`` of its own without disturbing the aliases that follow it, which
+ is a read of a table the mapping has no business reading; the same value
+ could append a ``WHERE`` and nothing would notice either.
+ * No comment, anywhere. A value that closes its own quote has to hide the
+ text `build_probe_sql` appended after it, and a comment is the only way
+ to do that and still balance the quotes -- so this is what makes the
+ alias check above sufficient rather than merely necessary. Read off the
+ parse rather than the text, so a comment *inside* a literal is data and
+ costs no pruning, and so the question is asked in the engine's own
+ dialect. A transform has no legitimate reason to carry one either; see
+ `EXECUTABLE_COMMENT_RE`.
+
+ Both FROM clauses are compared as sqlglot renders them, so the suffix's own
+ spacing does not have to match what the probe emitted. Identifier case
does,
+ which costs nothing: `_probe` hands the same engine constant to
+ `build_probe_sql` and to this gate.
+ """
+ # Before the parse, because this gate's whole contract is that what the
+ # parse describes is what the engine will run, and an executable comment is
+ # precisely the text where that stops being true. The transform is already
+ # refused for carrying one; this covers the compiled statement, so no later
+ # change to how values are rendered can reintroduce it behind the gates
+ # below.
+ if contains_executable_comment(sql) or
contains_unicode_escaped_identifier(sql):
+ return False
+
+ try:
+ script = SQLScript(sql, engine)
+ except SupersetParseError:
+ return False
+ if len(script.statements) != 1:
+ return False
+ statement = script.statements[0]
+ if not isinstance(statement, SQLStatement):
+ # A dialect whose statements this gate cannot take apart -- KQL -- gets
+ # no probe rather than an unchecked one. It never had one: the clause
+ # inspection below is implemented for SQL statements only, and the
+ # alternative to declining here is an `AttributeError` that `_probe`
+ # swallows into the same outcome, less legibly.
+ return False
+ if statement.has_comment():
+ return False
+ if statement.has_subquery():
+ return False
+ if statement.get_clause_names() - {"from"}:
+ return False
+ if statement.get_from_clause_sql() != _from_suffix_sql(from_suffix,
engine):
+ return False
+ return statement.get_select_aliases() == [f"v{index}" for index in
range(expected)]
+
+
+def _from_suffix_sql(from_suffix: str, engine: str) -> str | None:
+ """
+ The engine's own ``FROM`` suffix as its parsed clause, or ``None`` for
none.
+
+ Parsed rather than string-compared so that the comparison in
+ `probe_sql_is_evaluable` is between two rendered clauses. A suffix that
does
+ not parse answers ``None``, which no statement carrying a FROM can match --
+ the probe then declines, which is the right way for an unreadable engine
+ constant to fail.
+ """
+ if not from_suffix.strip():
+ return None
+ try:
+ return SQLStatement(f"SELECT 1{from_suffix}",
engine).get_from_clause_sql()
+ except SupersetParseError:
+ return None
+
+
+def evaluate_transform(
+ database: Database,
+ catalog: str | None,
+ schema: str | None,
+ transform: str,
+ values: list[Any],
+ *,
+ errors: list[str] | None = None,
+) -> list[Any] | None:
+ """
+ Evaluate ``transform`` against the engine once per distinct value.
+
+ Returns one result per input value, positionally aligned with ``values``,
or
+ ``None`` if anything at all goes wrong. Failing open costs pruning, never
+ correctness: the chart query still runs, it just scans more partitions.
+
+ The probe is pinned to the dataset's catalog and schema so session settings
+ match the chart query as closely as the connection pool allows. It still
+ runs in a *different* session, which is why transforms calling
+ session-dependent functions are rejected at save time.
+
+ :param errors: optional sink for the engine's own account of a failure. The
+ query path passes nothing and stays silent; the editor's preview passes
+ a list so it can tell the owner *why* the transform did not evaluate --
+ a misspelled function is the common case and sqlglot parses it happily.
+ """
+ if not values:
+ return None
+
+ # Dedupe so a 200-value `IN` list costs one column, not 200.
+ distinct: list[Any] = []
+ seen: set[Any] = set()
+ for value in values:
+ key = _hashable(value)
+ if key not in seen:
+ seen.add(key)
+ distinct.append(value)
+
+ # The value side of the premise `probe_sql_is_evaluable` checks on the
+ # finished statement: a value the driver and the engine would spell
+ # differently is not probed at all -- see `literal_round_trips`.
+ #
+ # `ExploreMixin.mirror_probe_request` declines one earlier, with a reason
+ # the preview can explain, and that is the gate an owner sees. This is the
+ # one that cannot be walked around. `_collect_partition_mirror_range`
+ # appends its bounds into the sink without passing through that method at
+ # all, and both paths can hand back a value the gate never saw: on a column
+ # carrying a `python_date_format`, what is probed is
+ # `strftime(that format)` -- text no mapping gate has ever read.
+ #
+ # Above `_run_probe` on purpose. This is a property of one input, not of
+ # the transform, and a verdict recorded here would withdraw the mirror for
+ # every later value of a transform the engine evaluates perfectly well.
+ dialect = _dialect_for(database)
+ if not all(
+ literal_round_trips(value, dialect, database.backend) for value in
distinct
+ ):
+ logger.warning(
+ "A filter value is not written the same way by the driver and the "
+ "database, so the partition transform is not probed at it; this "
+ "query will not prune"
+ )
+ return None
+
+ cache_key = _probe_cache_key(database, catalog, schema, transform,
distinct)
+ cached = _cache_get(cache_key)
+ if cached is None:
+ cached = _run_probe(
+ database, catalog, schema, transform, distinct, errors=errors
+ )
+ if cached is None:
+ # Deliberately not cached: a transient engine blip would otherwise
+ # keep the dataset pruning-free for the whole cache timeout.
+ return None
+ _cache_set(cache_key, cached)
+
+ evaluated = dict(
+ zip((_hashable(value) for value in distinct), cached, strict=False)
+ )
+ return [evaluated[_hashable(value)] for value in values]
+
+
+def _run_probe(
+ database: Database,
+ catalog: str | None,
+ schema: str | None,
+ transform: str,
+ distinct: list[Any],
+ *,
+ errors: list[str] | None = None,
+) -> list[Any] | None:
+ """
+ `_probe` plus the advisory record of how it went.
+
+ One place rather than one per `return`, because every way out of `_probe`
+ is a verdict and the next reader of `known_mirror_verdict` cannot tell the
+ difference between "declined" and "never asked".
+
+ The verdict is about the *transform*: whether the engine evaluated it at
+ all. A ``NULL`` among the results is not that -- it is this input's answer,
+ and `NULLIF(:value, 0)` returning ``NULL`` for ``n = 0`` says nothing about
+ the same transform on ``n = 2``. Counting it withdrew the promise for the
+ whole transform, and nothing restored it: a *failed* probe is deliberately
+ not cached, so the next chart re-probes and re-records, but a ``NULL`` is a
+ successful probe and *is* cached -- so the false verdict outlived every
+ later hit, and the editor reported a working mapping as not mirroring
+ while the query went on pruning. The per-input skip still happens where it
+ belongs, in the caller's own ``NULL`` guard.
+ """
+ values = _probe(database, catalog, schema, transform, distinct,
errors=errors)
+ record_mirror_verdict(
+ database,
+ catalog,
+ schema,
+ transform,
+ mirrors=values is not None,
+ )
+ return values
+
+
+def _probe(
+ database: Database,
+ catalog: str | None,
+ schema: str | None,
+ transform: str,
+ distinct: list[Any],
+ *,
+ errors: list[str] | None = None,
+) -> list[Any] | None:
+ # The last gate before the transform becomes SQL the engine runs, and the
+ # only one that covers a transform already in storage. The write-side
+ # checks can only speak for rows written after they existed; this speaks
+ # for every row, including ones a pre-fix release stored and ones a door
+ # that forgets to ask still lets in.
+ #
+ # Declining costs pruning, never correctness -- see `evaluate_transform`.
+ if reason := stored_expression_error(database, catalog, schema, transform):
+ logger.warning(
+ "Refusing to probe a partition transform that is not a storable "
+ "expression; queries will not prune: %s",
+ reason,
+ )
+ return None
+
+ try:
+ from_suffix = database.db_engine_spec.select_without_from_suffix
+ sql = build_probe_sql(
+ transform,
+ distinct,
+ _dialect_for(database),
+ from_suffix,
+ )
+ if not probe_sql_is_evaluable(
+ sql, database.backend, len(distinct), from_suffix
+ ):
+ # Declining rather than raising, for the same reason every other
+ # failure here declines: the chart query is already correct without
+ # the mirror, and it is the only thing the caller is waiting on.
+ logger.warning(
+ "Refusing to run a partition transform probe whose compiled
SQL "
+ "is not a plain projection per input value; queries will not "
+ "prune"
+ )
+ return None
+ frame = database.get_df(sql=sql, catalog=catalog, schema=schema)
+ if frame is None or frame.empty:
+ logger.warning(
+ "Partition transform probe returned no rows; skipping
mirroring"
+ )
+ return None
+ column_count = frame.shape[1]
+ if column_count != len(distinct):
+ # The results cannot be aligned back to their inputs; skipping
+ # beats guessing which value produced which column. Too *many*
+ # columns is the dangerous direction and the reason this is `!=`
+ # rather than `<`: a transform whose select list holds two
+ # expressions returns 2N columns for N inputs, and reading the
+ # first N of them interleaves the expressions instead of selecting
+ # one per value -- a predicate built from the wrong values rather
+ # than one that is merely short. `is_parseable` rejects that
+ # transform before it is ever stored; this is the backstop for one
+ # that predates the check.
+ logger.warning(
+ "Partition transform probe returned %d values for %d inputs",
+ column_count,
+ len(distinct),
+ )
+ return None
+ # Cell-wise rather than through `frame.iloc[0]`. A row is a Series, so
+ # it carries one dtype for every probe column: a row mixing an exact
+ # int64 with a float unifies to float64, and an integer partition key
+ # above 2^53 comes back rounded. `_to_python_scalar` converts
+ # faithfully but runs after the loss, so the mirror asks for a key the
+ # warehouse does not hold and drops the row the filter matched.
+ return [
+ _to_python_scalar(frame.iat[0, index]) for index in
range(len(distinct))
+ ]
+ except Exception as ex: # pylint: disable=broad-except
+ logger.warning(
+ "Partition transform probe failed; queries will not prune",
+ exc_info=True,
+ )
+ if errors is not None:
+ errors.append(str(ex))
+ return None
+
+
+def _to_python_scalar(value: Any) -> Any:
+ """
+ A probed value as a type SQLAlchemy can render and bind.
+
+ The probe reads its results out of a pandas frame, so a numeric column
+ arrives as a `numpy.int64` and a temporal one as a `pandas.Timestamp`.
+ SQLAlchemy has no literal renderer for either: `sa.literal(np.int64(...))`
+ infers `NullType` and raises `CompileError`, which is a 500 from the
preview
+ endpoint for the canonical epoch transform -- the most ordinary mapping
+ there is.
+
+ Pandas' missing-value sentinels are folded into `None` on the way through.
+ `NaT` is not a `Timestamp` and has no renderer either, and a transform that
+ returns nothing for an input it cannot convert is exactly the NULL case the
+ mirror already admits.
+ """
+ if value is None:
+ return None
+ try:
+ if pd.isna(value):
+ return None
+ except (TypeError, ValueError):
+ # Not something `isna` can judge (a list, a dict); pass it through and
+ # let the dialect decide.
+ pass
+ if isinstance(value, pd.Timestamp):
+ return value.to_pydatetime()
+ if isinstance(value, np.generic):
+ return value.item()
+ return value
+
+
+def _execution_identity(database: Database) -> str | None:
+ """
+ Who the warehouse will run the probe as, when that can vary by caller.
+
+ `_probe_cache_key` keys on the `Database` record, which is the *connection*
+ -- not the identity it is opened under. Two hooks make that identity a
+ function of the Superset user instead:
+
+ * ``impersonate_user`` on the database, which hands the effective username
+ to `db_engine_spec.impersonate_user`;
+ * ``DB_CONNECTION_MUTATOR``, which receives the effective username and may
+ return an entirely different account's URL.
+
+ Under either one, a cached probe result computed under user A's grants was
+ served to user B, and the preview echoed it back in ``emitted_predicate``.
+ A transform wrapping a read-capable function the denylist does not name --
+ Oracle's ``DBMS_XMLGEN.GETXML`` is the worked example -- then leaks across
+ users who were never allowed the same rows.
+
+ Returns ``None`` when neither hook is configured, which is the common case
+ and deliberately leaves the key as it was: the cache exists to keep a
+ synchronous warehouse round trip off the chart-query path, and keying every
+ deployment on the username would cost every deployment the hit rate to fix
+ the two that need it.
+
+ The *Superset* username rather than the resolved warehouse account, because
+ it is the input both hooks branch on, and reading it needs no URL parse and
+ puts no credential in the key.
+ """
+ if not (database.impersonate_user or app.config["DB_CONNECTION_MUTATOR"]):
+ return None
+ return get_username()
+
+
+def _probe_cache_key(
+ database: Database,
+ catalog: str | None,
+ schema: str | None,
+ transform: str,
+ values: list[Any],
+) -> str:
+ """
+ Key on everything that can change the answer.
+
+ Note this cache is independent of the chart-data cache: it is keyed on the
+ transform and its inputs, so it is correct to share across every chart on
+ every dataset that happens to use the same transform.
+ """
+ payload = json.dumps(
+ [
+ database.id,
+ database.backend,
+ # The probe asks this connection to evaluate the transform, so the
+ # answer belongs to it. `id` outlives an edit to the URI or to
+ # `extra` (a session timezone, say), which would otherwise serve
+ # values computed against the old environment until the entry
+ # expires. `changed_on` covers the edits that do not show up here,
+ # such as a rotated password, without putting a secret in the key.
+ database.sqlalchemy_uri,
+ database.extra,
+ str(database.changed_on),
+ catalog,
+ schema,
+ transform,
+ [repr(value) for value in values],
+ _execution_identity(database),
+ ],
+ default=repr,
+ )
+ digest = hashlib.md5(payload.encode("utf-8")).hexdigest() # noqa: S324
Review Comment:
`hashlib.md5` here raises `ValueError` on a FIPS-mode OpenSSL build, and
`_probe_cache_key` is called from `evaluate_transform` with no surrounding try.
With `PARTITION_FILTER_MAPPING` on, any chart filtering on a mapped column (and
the preview endpoint) would then return a 500 instead of just skipping pruning,
which contradicts the module's "a failure costs pruning, never correctness"
promise. Could this use `superset.utils.hashing` (or `usedforsecurity=False`)
like the rest of the codebase?
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