sadpandajoe commented on code in PR #43870:
URL: https://github.com/apache/superset/pull/43870#discussion_r4236241864
##########
superset-frontend/src/components/Datasource/components/DatasourceEditor/DatasourceEditor.tsx:
##########
@@ -1359,15 +1673,63 @@ function DatasourceEditor({
const newCols = await fetchSyncedColumns(datasource, signal);
const columnChanges = updateColumns(
- datasource.columns,
+ currentColumns,
Review Comment:
`currentColumns` is captured before `await fetchSyncedColumns(...)`, and the
result then replaces `databaseColumns` wholesale. If the owner starts "Sync
columns from source" with an active implicit mapping and clicks "Remove
mapping" while the request is pending, the unchanged-column response merges
against the stale snapshot, restores the transform and monotonicity flag, and
silently re-activates the mapping that was removed; saving persists it. Adding
`currentColumns` to the dependency list does not help an invocation already in
flight. Could the merge read the latest column state when the response arrives
(e.g. via a ref or functional state update)?
##########
superset/connectors/sqla/partition_mapping.py:
##########
@@ -0,0 +1,2770 @@
+# 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.
+
+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")
+
+#: Balanced Jinja blocks. The probe would render these in a different context
+#: at a different time from the chart query, so they are rejected at save time.
+JINJA_BLOCK_RE = re.compile(r"\{\{.*?\}\}|\{%.*?%\}|\{#.*?#\}", re.DOTALL)
+
+#: 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?!")
+
+#: 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.
+NON_DETERMINISTIC_FUNCTIONS = {
+ "CURRENT_DATE",
+ "CURRENT_TIME",
+ "CURRENT_TIMESTAMP",
+ "NOW",
+ "RAND",
+ "RANDOM",
+ "UUID",
+}
+
+#: 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}
+
+
+#: Returned by `ExploreMixin.mirror_probe_request` for a filter no mirror can
+#: stand in for: one the engine compares more coarsely than the value carries,
a
+#: value it cannot render as a literal, or an ``IN`` list with a member of
+#: either kind. A sentinel rather than `None`, because `None` is a filter value
+#: in its own right.
+#:
+#: Lives here rather than beside that method so the preview can read it too:
+#: `superset.models.helpers` imports this module, so the sentinel can only
cross
+#: the boundary in this direction. Both callers have to recognise the same
+#: object -- a preview that answered "valid" for a request the chart path
+#: declines is the drift this is here to prevent.
+UNMIRRORABLE = object()
+
+
+#: 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 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.
+
+ 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
+ try:
+ is_string = column.type_generic == utils.GenericDataType.STRING
+ except Exception: # pylint: disable=broad-except # noqa: BLE001
+ # An unresolvable type is treated as a string: the gate exists to stop
+ # a silent wrong answer, so it fails closed.
+ return False
+ if not is_string:
+ return True
+ return bool(db_engine_spec.binary_string_comparison)
Review Comment:
The docstring says trailing-space-insensitive `CHAR` comparison is covered,
but this returns the engine-wide flag for every string column, and
`PostgresBaseEngineSpec` sets it to `True` (so `RedshiftEngineSpec` inherits it
too). With PostgreSQL `country CHAR(2)`, a text partition key and transform
`lower(:value)`, the filter `country = 'US '` still matches the row, but the
probe yields `'us '` and the added `region_key = 'us '` predicate drops it.
Redshift VARCHAR ignores trailing spaces the same way, so a length-based
transform hits it too. Should padded character types (and Redshift) decline
equality here instead of relying on the engine-level flag?
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