On 2017/06/09 20:47, Ashutosh Bapat wrote:
> Thanks for the long explanation. I guess, this should be written in
> comments somewhere in the code there. I see following comment in
> ATExecAttachPartition()
> --
> *
> * There is a case in which we cannot rely on just the result of the
> * proof.
> */
>
> --
>
> I guess, this comment should be expanded to explain what you wrote above.
Tried in the attached updated patch.
Thanks,
Amit
From a98ea14dd3aa57f06d7066ee996c54f42a3014ac Mon Sep 17 00:00:00 2001
From: amit <amitlangot...@gmail.com>
Date: Thu, 8 Jun 2017 14:01:34 +0900
Subject: [PATCH] Fixes around partition constraint handling when attaching
Failure to map attribute numbers in the partition key expressions to
to partition's would cause predicate_implied_by() to unnecessarily
return 'false', in turn causing the failure to skip the validation
scan.
Conversely, failure to map partition's NOT NULL column's attribute
numbers to parent's might cause incorrect conclusion about which
columns of the partition being attached must have NOT NULL constraint
defined on them.
Rearrange code and comments a little around this area to make things
clearer.
---
src/backend/commands/tablecmds.c | 122 +++++++++++++++---------------
src/test/regress/expected/alter_table.out | 32 ++++++++
src/test/regress/sql/alter_table.sql | 31 ++++++++
3 files changed, 126 insertions(+), 59 deletions(-)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b61fda9909..13fbed9431 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -13409,6 +13409,7 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
List *childrels;
TupleConstr *attachRel_constr;
List *partConstraint,
+ *partConstraintOrig,
*existConstraint;
SysScanDesc scan;
ScanKeyData skey;
@@ -13574,14 +13575,37 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
partConstraint = list_make1(make_ands_explicit(partConstraint));
/*
+ * Adjust the generated constraint to match this partition's attribute
+ * numbers. Save the original to be used later if we decide to proceed
+ * with the validation scan after all.
+ */
+ partConstraintOrig = copyObject(partConstraint);
+ partConstraint = map_partition_varattnos(partConstraint, 1, attachRel,
+
rel);
+
+ /*
* Check if we can do away with having to scan the table being attached
to
* validate the partition constraint, by *proving* that the existing
* constraints of the table *imply* the partition predicate. We include
- * the table's check constraints and NOT NULL constraints in the list of
- * clauses passed to predicate_implied_by().
- *
- * There is a case in which we cannot rely on just the result of the
- * proof.
+ * only the table's check constraints in the list of "restrictions"
passed
+ * to predicate_implied_by() and do not include the NullTest expressions
+ * corresponding to any NOT NULL constraints that the table might have,
+ * because we do not want to depend on predicate_implied_by's proof for
+ * the requirement (if any) that there not be any null values in the
+ * partition keys of the existing rows. As written in the comments at
+ * the top of predicate_implied_by_simple_clause(), the restriction
clause
+ * that it receives is assumed to be a WHERE restriction wherein NULL
+ * result means 'false' so that any rows that it selects must have
non-null
+ * value in the respective column (an implicit NOT NULL constraint).
But
+ * in this case, we are passing the list of restrictions that are
table's
+ * constraints wherein NULL result means 'true', so even rows with null
+ * values in the respective columns would have been admitted into the
+ * table, whereas, per aforementioned, predicate_implied_by() proof
would
+ * say there cannot be any null values in those columns based on those
+ * restrictions. The only way to confirm NOT NULLness then is by
looking
+ * for explicit NOT NULL constraints on the partition key columns. If
any
+ * partition key is an expression, for which there cannot be a NOT NULL
+ * constraint, we simply give up on skipping the scan.
*/
attachRel_constr = tupleDesc->constr;
existConstraint = NIL;
@@ -13589,42 +13613,36 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
{
int num_check = attachRel_constr->num_check;
int i;
+ AttrNumber *parent_attnos;
Bitmapset *not_null_attrs = NULL;
List *part_constr;
ListCell *lc;
- bool partition_accepts_null = true;
+ bool partition_accepts_null;
int partnatts;
if (attachRel_constr->has_not_null)
{
int natts =
attachRel->rd_att->natts;
+ parent_attnos =
+
convert_tuples_by_name_map(RelationGetDescr(rel),
+
RelationGetDescr(attachRel),
+
gettext_noop("could not convert row type"));
for (i = 1; i <= natts; i++)
{
Form_pg_attribute att =
attachRel->rd_att->attrs[i - 1];
+ /*
+ * We check below if this NOT NULL attribute in
the partition
+ * is a key column. Instead of storing the
partition's own
+ * attribute number however, we need to store
the parent's
+ * corresponding attribute number, because we
will be comparing
+ * against the partition key which contains
parent's attribute
+ * numbers.
+ */
if (att->attnotnull && !att->attisdropped)
- {
- NullTest *ntest = makeNode(NullTest);
-
- ntest->arg = (Expr *) makeVar(1,
-
i,
-
att->atttypid,
-
att->atttypmod,
-
att->attcollation,
-
0);
- ntest->nulltesttype = IS_NOT_NULL;
-
- /*
- * argisrow=false is correct even for a
composite column,
- * because attnotnull does not
represent a SQL-spec IS NOT
- * NULL test in such a case, just IS
DISTINCT FROM NULL.
- */
- ntest->argisrow = false;
- ntest->location = -1;
- existConstraint =
lappend(existConstraint, ntest);
- not_null_attrs =
bms_add_member(not_null_attrs, i);
- }
+ not_null_attrs =
bms_add_member(not_null_attrs,
+
parent_attnos[i - 1]);
}
}
@@ -13661,30 +13679,12 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
skip_validate = true;
/*
- * We choose to err on the safer side, i.e., give up on
skipping the
- * validation scan, if the partition key column doesn't have
the NOT
- * NULL constraint and the table is to become a list partition
that
- * does not accept nulls. In this case, the partition predicate
- * (partConstraint) does include an 'key IS NOT NULL'
expression,
- * however, because of the way
predicate_implied_by_simple_clause() is
- * designed to handle IS NOT NULL predicates in the absence of
a IS
- * NOT NULL clause, we cannot rely on just the above proof.
- *
- * That is not an issue in case of a range partition, because
if there
- * were no NOT NULL constraint defined on the key columns, an
error
- * would be thrown before we get here anyway. That is not true,
- * however, if any of the partition keys is an expression,
which is
- * handled below.
+ * First determine if the partition accepts NULL; it doesn't if
there
+ * is an IS NOT NULL expression in the partition constraint.
*/
part_constr = linitial(partConstraint);
part_constr = make_ands_implicit((Expr *) part_constr);
-
- /*
- * part_constr contains an IS NOT NULL expression, if this is a
list
- * partition that does not accept nulls (in fact, also if this
is a
- * range partition and some partition key is an expression, but
we
- * never skip validation in that case anyway; see below)
- */
+ partition_accepts_null = true;
foreach(lc, part_constr)
{
Node *expr = lfirst(lc);
@@ -13697,18 +13697,22 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
}
}
- partnatts = get_partition_natts(key);
- for (i = 0; i < partnatts; i++)
+ if (!partition_accepts_null)
{
- AttrNumber partattno;
-
- partattno = get_partition_col_attnum(key, i);
+ /* Check that none of the partition keys allows null
values. */
+ partnatts = get_partition_natts(key);
+ for (i = 0; i < partnatts; i++)
+ {
+ AttrNumber partattno =
get_partition_col_attnum(key, i);
- /* If partition key is an expression, must not skip
validation */
- if (!partition_accepts_null &&
- (partattno == 0 ||
- !bms_is_member(partattno, not_null_attrs)))
- skip_validate = false;
+ /* We don't know much about the expression
keys. */
+ if (partattno == 0 ||
+ !bms_is_member(partattno,
not_null_attrs))
+ {
+ skip_validate = false;
+ break;
+ }
+ }
}
}
@@ -13763,7 +13767,7 @@ ATExecAttachPartition(List **wqueue, Relation rel,
PartitionCmd *cmd)
tab = ATGetQueueEntry(wqueue, part_rel);
/* Adjust constraint to match this partition */
- constr = linitial(partConstraint);
+ constr = linitial(partConstraintOrig);
tab->partition_constraint = (Expr *)
map_partition_varattnos((List *) constr, 1,
part_rel, rel);
diff --git a/src/test/regress/expected/alter_table.out
b/src/test/regress/expected/alter_table.out
index 8aadbb88a3..222d7e13d3 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3301,6 +3301,17 @@ ALTER TABLE list_parted2 DETACH PARTITION part_3_4;
ALTER TABLE part_3_4 ALTER a SET NOT NULL;
ALTER TABLE list_parted2 ATTACH PARTITION part_3_4 FOR VALUES IN (3, 4);
INFO: partition constraint for table "part_3_4" is implied by existing
constraints
+-- check that able to handle different ordering of attributes when analyzing
+-- table's constraint to skip the validation scan
+CREATE TABLE part_6 (
+ c int,
+ b char,
+ a int NOT NULL,
+ CONSTRAINT check_a CHECK (a IN (6))
+);
+ALTER TABLE part_6 DROP c;
+ALTER TABLE list_parted2 ATTACH PARTITION part_6 FOR VALUES IN (6);
+INFO: partition constraint for table "part_6" is implied by existing
constraints
-- check validation when attaching range partitions
CREATE TABLE range_parted (
a int,
@@ -3326,6 +3337,27 @@ CREATE TABLE part2 (
);
ALTER TABLE range_parted ATTACH PARTITION part2 FOR VALUES FROM (1, 10) TO (1,
20);
INFO: partition constraint for table "part2" is implied by existing
constraints
+-- check that able to handle different ordering of attributes when analyzing
+-- table's constraint to skip the validation scan
+CREATE TABLE part3 (
+ c int,
+ a int NOT NULL CHECK (a = 1),
+ b int NOT NULL CHECK (b >= 21 AND b < 25)
+);
+ALTER TABLE part3 DROP c;
+ALTER TABLE range_parted ATTACH PARTITION part3 FOR VALUES FROM (1, 20) TO (1,
30);
+INFO: partition constraint for table "part3" is implied by existing
constraints
+-- check that null values in the range partition key are correctly
+-- reported
+CREATE TABLE part4 (
+ c int,
+ a int CHECK (a = 1),
+ b int CHECK (b >= 21 AND b < 25)
+);
+ALTER TABLE part4 DROP c;
+INSERT INTO part4 VALUES (null, null);
+ALTER TABLE range_parted ATTACH PARTITION part4 FOR VALUES FROM (1, 30) TO (1,
40);
+ERROR: partition constraint is violated by some row
-- check that leaf partitions are scanned when attaching a partitioned
-- table
CREATE TABLE part_5 (
diff --git a/src/test/regress/sql/alter_table.sql
b/src/test/regress/sql/alter_table.sql
index c41b48785b..16edce89f8 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2128,6 +2128,16 @@ ALTER TABLE list_parted2 DETACH PARTITION part_3_4;
ALTER TABLE part_3_4 ALTER a SET NOT NULL;
ALTER TABLE list_parted2 ATTACH PARTITION part_3_4 FOR VALUES IN (3, 4);
+-- check that able to handle different ordering of attributes when analyzing
+-- table's constraint to skip the validation scan
+CREATE TABLE part_6 (
+ c int,
+ b char,
+ a int NOT NULL,
+ CONSTRAINT check_a CHECK (a IN (6))
+);
+ALTER TABLE part_6 DROP c;
+ALTER TABLE list_parted2 ATTACH PARTITION part_6 FOR VALUES IN (6);
-- check validation when attaching range partitions
CREATE TABLE range_parted (
@@ -2156,6 +2166,27 @@ CREATE TABLE part2 (
);
ALTER TABLE range_parted ATTACH PARTITION part2 FOR VALUES FROM (1, 10) TO (1,
20);
+-- check that able to handle different ordering of attributes when analyzing
+-- table's constraint to skip the validation scan
+CREATE TABLE part3 (
+ c int,
+ a int NOT NULL CHECK (a = 1),
+ b int NOT NULL CHECK (b >= 21 AND b < 25)
+);
+ALTER TABLE part3 DROP c;
+ALTER TABLE range_parted ATTACH PARTITION part3 FOR VALUES FROM (1, 20) TO (1,
30);
+
+-- check that null values in the range partition key are correctly
+-- reported
+CREATE TABLE part4 (
+ c int,
+ a int CHECK (a = 1),
+ b int CHECK (b >= 21 AND b < 25)
+);
+ALTER TABLE part4 DROP c;
+INSERT INTO part4 VALUES (null, null);
+ALTER TABLE range_parted ATTACH PARTITION part4 FOR VALUES FROM (1, 30) TO (1,
40);
+
-- check that leaf partitions are scanned when attaching a partitioned
-- table
CREATE TABLE part_5 (
--
2.11.0
--
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