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Allow some exclusion constraints on partitions

Browse source 
Previously we only allowed unique B-tree constraints on partitions
(and only if the constraint included all the partition keys).  But we
could allow exclusion constraints with the same restriction.  We also
require that those columns be compared for equality, not something
like &&.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Ronan Dunklau <ronan.dunklau@aiven.io>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://www.postgresql.org/message-id/flat/ec8b1d9b-502e-d1f8-e909-1bf9dffe6fa5@illuminatedcomputing.com
This commit is contained in:
Peter Eisentraut 2023-07-12 09:24:43 +02:00
parent ce0b0fa3e7
commit 8c852ba9a4
13 changed files with 284 additions and 73 deletions
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2
contrib/btree_gist/Makefile
View file

@ -38,7 +38,7 @@ PGFILEDESC = "btree_gist - B-tree equivalent GiST operator classes"
REGRESS = init int2 int4 int8 float4 float8 cash oid timestamp timestamptz \
time timetz date interval macaddr macaddr8 inet cidr text varchar char \
bytea bit varbit numeric uuid not_equal enum bool
bytea bit varbit numeric uuid not_equal enum bool partitions
SHLIB_LINK += $(filter -lm, $(LIBS))

82
contrib/btree_gist/expected/partitions.out Normal file
View file

@ -0,0 +1,82 @@
-- Make sure we can create an exclusion constraint
-- across a partitioned table.
-- That code looks at strategy numbers that can differ in regular gist vs btree_gist,
-- so we want to make sure it works here too.
create table parttmp (
id int,
valid_at daterange,
exclude using gist (id with =, valid_at with &&)
) partition by range (id);
create table parttmp_1_to_10 partition of parttmp for values from (1) to (10);
create table parttmp_11_to_20 partition of parttmp for values from (11) to (20);
insert into parttmp (id, valid_at) values
(1, '[2000-01-01, 2000-02-01)'),
(1, '[2000-02-01, 2000-03-01)'),
(2, '[2000-01-01, 2000-02-01)'),
(11, '[2000-01-01, 2000-02-01)'),
(11, '[2000-02-01, 2000-03-01)'),
(12, '[2000-01-01, 2000-02-01)');
select * from parttmp order by id, valid_at;
id | valid_at
----+-------------------------
1 | [01-01-2000,02-01-2000)
1 | [02-01-2000,03-01-2000)
2 | [01-01-2000,02-01-2000)
11 | [01-01-2000,02-01-2000)
11 | [02-01-2000,03-01-2000)
12 | [01-01-2000,02-01-2000)
(6 rows)
select * from parttmp_1_to_10 order by id, valid_at;
id | valid_at
----+-------------------------
1 | [01-01-2000,02-01-2000)
1 | [02-01-2000,03-01-2000)
2 | [01-01-2000,02-01-2000)
(3 rows)
select * from parttmp_11_to_20 order by id, valid_at;
id | valid_at
----+-------------------------
11 | [01-01-2000,02-01-2000)
11 | [02-01-2000,03-01-2000)
12 | [01-01-2000,02-01-2000)
(3 rows)
update parttmp set valid_at = valid_at * '[2000-01-15,2000-02-15)' where id = 1;
select * from parttmp order by id, valid_at;
id | valid_at
----+-------------------------
1 | [01-15-2000,02-01-2000)
1 | [02-01-2000,02-15-2000)
2 | [01-01-2000,02-01-2000)
11 | [01-01-2000,02-01-2000)
11 | [02-01-2000,03-01-2000)
12 | [01-01-2000,02-01-2000)
(6 rows)
select * from parttmp_1_to_10 order by id, valid_at;
id | valid_at
----+-------------------------
1 | [01-15-2000,02-01-2000)
1 | [02-01-2000,02-15-2000)
2 | [01-01-2000,02-01-2000)
(3 rows)
select * from parttmp_11_to_20 order by id, valid_at;
id | valid_at
----+-------------------------
11 | [01-01-2000,02-01-2000)
11 | [02-01-2000,03-01-2000)
12 | [01-01-2000,02-01-2000)
(3 rows)
-- make sure the excluson constraint excludes:
insert into parttmp (id, valid_at) values
(2, '[2000-01-15, 2000-02-01)');
ERROR: conflicting key value violates exclusion constraint "parttmp_1_to_10_id_valid_at_excl"
DETAIL: Key (id, valid_at)=(2, [01-15-2000,02-01-2000)) conflicts with existing key (id, valid_at)=(2, [01-01-2000,02-01-2000)).
drop table parttmp;
-- should fail with a good error message:
create table parttmp (id int, valid_at daterange, exclude using gist (id with <>, valid_at with &&)) partition by range (id);
ERROR: cannot match partition key to index on column "id" using non-equal operator "<>"

1
contrib/btree_gist/meson.build
View file

@ -88,6 +88,7 @@ tests += {
'not_equal',
'enum',
'bool',
'partitions',
],
},
}

39
contrib/btree_gist/sql/partitions.sql Normal file
View file

@ -0,0 +1,39 @@
-- Make sure we can create an exclusion constraint
-- across a partitioned table.
-- That code looks at strategy numbers that can differ in regular gist vs btree_gist,
-- so we want to make sure it works here too.
create table parttmp (
id int,
valid_at daterange,
exclude using gist (id with =, valid_at with &&)
) partition by range (id);
create table parttmp_1_to_10 partition of parttmp for values from (1) to (10);
create table parttmp_11_to_20 partition of parttmp for values from (11) to (20);
insert into parttmp (id, valid_at) values
(1, '[2000-01-01, 2000-02-01)'),
(1, '[2000-02-01, 2000-03-01)'),
(2, '[2000-01-01, 2000-02-01)'),
(11, '[2000-01-01, 2000-02-01)'),
(11, '[2000-02-01, 2000-03-01)'),
(12, '[2000-01-01, 2000-02-01)');
select * from parttmp order by id, valid_at;
select * from parttmp_1_to_10 order by id, valid_at;
select * from parttmp_11_to_20 order by id, valid_at;
update parttmp set valid_at = valid_at * '[2000-01-15,2000-02-15)' where id = 1;
select * from parttmp order by id, valid_at;
select * from parttmp_1_to_10 order by id, valid_at;
select * from parttmp_11_to_20 order by id, valid_at;
-- make sure the excluson constraint excludes:
insert into parttmp (id, valid_at) values
(2, '[2000-01-15, 2000-02-01)');
drop table parttmp;
-- should fail with a good error message:
create table parttmp (id int, valid_at daterange, exclude using gist (id with <>, valid_at with &&)) partition by range (id);

12
doc/src/sgml/ddl.sgml
View file

@ -4216,11 +4216,13 @@ ALTER INDEX measurement_city_id_logdate_key
<listitem>
<para>
There is no way to create an exclusion constraint spanning the
whole partitioned table. It is only possible to put such a
constraint on each leaf partition individually. Again, this
limitation stems from not being able to enforce cross-partition
restrictions.
Similarly an exclusion constraint must include all the
partition key columns. Furthermore the constraint must compare those
columns for equality (not e.g. <literal>&amp;&amp;</literal>).
Again, this limitation stems from not being able to enforce
cross-partition restrictions. The constraint may include additional
columns that aren't part of the partition key, and it may compare
those with any operators you like.
</para>
</listitem>

59
src/backend/commands/indexcmds.c
View file

@ -712,11 +712,6 @@ DefineIndex(Oid relationId,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot create index on partitioned table \"%s\" concurrently",
RelationGetRelationName(rel))));
if (stmt->excludeOpNames)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot create exclusion constraints on partitioned table \"%s\"",
RelationGetRelationName(rel))));
}
/*
@ -923,15 +918,16 @@ DefineIndex(Oid relationId,
index_check_primary_key(rel, indexInfo, is_alter_table, stmt);
/*
* If this table is partitioned and we're creating a unique index or a
* primary key, make sure that the partition key is a subset of the
* index's columns. Otherwise it would be possible to violate uniqueness
* by putting values that ought to be unique in different partitions.
* If this table is partitioned and we're creating a unique index, primary
* key, or exclusion constraint, make sure that the partition key is a
* subset of the index's columns. Otherwise it would be possible to
* violate uniqueness by putting values that ought to be unique in
* different partitions.
*
* We could lift this limitation if we had global indexes, but those have
* their own problems, so this is a useful feature combination.
*/
if (partitioned && (stmt->unique || stmt->primary))
if (partitioned && (stmt->unique || stmt->excludeOpNames))
{
PartitionKey key = RelationGetPartitionKey(rel);
const char *constraint_type;
@ -941,7 +937,7 @@ DefineIndex(Oid relationId,
constraint_type = "PRIMARY KEY";
else if (stmt->unique)
constraint_type = "UNIQUE";
else if (stmt->excludeOpNames != NIL)
else if (stmt->excludeOpNames)
constraint_type = "EXCLUDE";
else
{
@ -984,11 +980,11 @@ DefineIndex(Oid relationId,
* We'll need to be able to identify the equality operators
* associated with index columns, too. We know what to do with
* btree opclasses; if there are ever any other index types that
* support unique indexes, this logic will need extension.
* support unique indexes, this logic will need extension. But if
* we have an exclusion constraint, it already knows the
* operators, so we don't have to infer them.
*/
if (accessMethodId == BTREE_AM_OID)
eq_strategy = BTEqualStrategyNumber;
else
if (stmt->unique && accessMethodId != BTREE_AM_OID)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot match partition key to an index using access method \"%s\"",
@ -1019,17 +1015,38 @@ DefineIndex(Oid relationId,
&idx_opfamily,
&idx_opcintype))
{
Oid idx_eqop;
Oid idx_eqop = InvalidOid;
if (stmt->unique)
idx_eqop = get_opfamily_member(idx_opfamily,
idx_opcintype,
idx_opcintype,
BTEqualStrategyNumber);
else if (stmt->excludeOpNames)
idx_eqop = indexInfo->ii_ExclusionOps[j];
Assert(idx_eqop);
idx_eqop = get_opfamily_member(idx_opfamily,
idx_opcintype,
idx_opcintype,
eq_strategy);
if (ptkey_eqop == idx_eqop)
{
found = true;
break;
}
else if (stmt->excludeOpNames)
{
/*
* We found a match, but it's not an equality
* operator. Instead of failing below with an
* error message about a missing column, fail now
* and explain that the operator is wrong.
*/
Form_pg_attribute att = TupleDescAttr(RelationGetDescr(rel), key->partattrs[i] - 1);
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot match partition key to index on column \"%s\" using non-equal operator \"%s\"",
NameStr(att->attname),
get_opname(indexInfo->ii_ExclusionOps[j]))));
}
}
}
}
@ -1101,7 +1118,7 @@ DefineIndex(Oid relationId,
constraint_type = "PRIMARY KEY";
else if (stmt->unique)
constraint_type = "UNIQUE";
else if (stmt->excludeOpNames != NIL)
else if (stmt->excludeOpNames)
constraint_type = "EXCLUDE";
else
{

6
src/backend/parser/parse_utilcmd.c
View file

@ -900,12 +900,6 @@ transformTableConstraint(CreateStmtContext *cxt, Constraint *constraint)
errmsg("exclusion constraints are not supported on foreign tables"),
parser_errposition(cxt->pstate,
constraint->location)));
if (cxt->ispartitioned)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("exclusion constraints are not supported on partitioned tables"),
parser_errposition(cxt->pstate,
constraint->location)));
cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
break;

7
src/test/regress/expected/alter_table.out
View file

@ -3834,16 +3834,11 @@ Referenced by:
TABLE "ataddindex" CONSTRAINT "ataddindex_ref_id_fkey" FOREIGN KEY (ref_id) REFERENCES ataddindex(id)
DROP TABLE ataddindex;
-- unsupported constraint types for partitioned tables
-- cannot drop column that is part of the partition key
CREATE TABLE partitioned (
a int,
b int
) PARTITION BY RANGE (a, (a+b+1));
ALTER TABLE partitioned ADD EXCLUDE USING gist (a WITH &&);
ERROR: exclusion constraints are not supported on partitioned tables
LINE 1: ALTER TABLE partitioned ADD EXCLUDE USING gist (a WITH &&);
^
-- cannot drop column that is part of the partition key
ALTER TABLE partitioned DROP COLUMN a;
ERROR: cannot drop column "a" because it is part of the partition key of relation "partitioned"
ALTER TABLE partitioned ALTER COLUMN a TYPE char(5);

8
src/test/regress/expected/create_table.out
View file

@ -153,14 +153,6 @@ CREATE TABLE partitioned (
a2 int
) PARTITION BY LIST (a1, a2); -- fail
ERROR: cannot use "list" partition strategy with more than one column
-- unsupported constraint type for partitioned tables
CREATE TABLE partitioned (
a int,
EXCLUDE USING gist (a WITH &&)
) PARTITION BY RANGE (a);
ERROR: exclusion constraints are not supported on partitioned tables
LINE 3: EXCLUDE USING gist (a WITH &&)
^
-- prevent using prohibited expressions in the key
CREATE FUNCTION retset (a int) RETURNS SETOF int AS $$ SELECT 1; $$ LANGUAGE SQL IMMUTABLE;
CREATE TABLE partitioned (

73
src/test/regress/expected/indexing.out
View file

@ -986,11 +986,32 @@ DETAIL: PRIMARY KEY constraint on table "idxpart" lacks column "a" which is par
-- OK if you use them in some other order
create table idxpart (a int, b int, c text, primary key (a, b, c)) partition by range (b, c, a);
drop table idxpart;
-- not other types of index-based constraints
create table idxpart (a int, exclude (a with = )) partition by range (a);
ERROR: exclusion constraints are not supported on partitioned tables
LINE 1: create table idxpart (a int, exclude (a with = )) partition ...
^
-- OK to add an exclusion constraint if partitioning by its equal column
create table idxpart (a int4range, exclude USING GIST (a with = )) partition by range (a);
drop table idxpart;
-- OK more than one equal column
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with =)) partition by range (a, b);
drop table idxpart;
-- OK with more than one equal column: constraint is a proper superset of partition key
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with =)) partition by range (a);
drop table idxpart;
-- Not OK more than one equal column: partition keys are a proper superset of constraint
create table idxpart (a int4range, b int4range, exclude USING GIST (a with = )) partition by range (a, b);
ERROR: unique constraint on partitioned table must include all partitioning columns
DETAIL: EXCLUDE constraint on table "idxpart" lacks column "b" which is part of the partition key.
-- Not OK with just -|-
create table idxpart (a int4range, exclude USING GIST (a with -|- )) partition by range (a);
ERROR: cannot match partition key to index on column "a" using non-equal operator "-|-"
-- OK with equals and &&, and equals is the partition key
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with &&)) partition by range (a);
drop table idxpart;
-- Not OK with equals and &&, and equals is not the partition key
create table idxpart (a int4range, b int4range, c int4range, exclude USING GIST (b with =, c with &&)) partition by range (a);
ERROR: unique constraint on partitioned table must include all partitioning columns
DETAIL: EXCLUDE constraint on table "idxpart" lacks column "a" which is part of the partition key.
-- OK more than one equal column and a && column
create table idxpart (a int4range, b int4range, c int4range, exclude USING GIST (a with =, b with =, c with &&)) partition by range (a, b);
drop table idxpart;
-- no expressions in partition key for PK/UNIQUE
create table idxpart (a int primary key, b int) partition by range ((b + a));
ERROR: unsupported PRIMARY KEY constraint with partition key definition
@ -1047,12 +1068,42 @@ Indexes:
Number of partitions: 0
drop table idxpart;
-- Exclusion constraints cannot be added
create table idxpart (a int, b int) partition by range (a);
alter table idxpart add exclude (a with =);
ERROR: exclusion constraints are not supported on partitioned tables
LINE 1: alter table idxpart add exclude (a with =);
^
-- Exclusion constraints can be added if partitioning by their equal column
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =);
drop table idxpart;
-- OK more than one equal column
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =, b with =);
drop table idxpart;
-- OK with more than one equal column: constraint is a proper superset of partition key
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =, b with =);
drop table idxpart;
-- Not OK more than one equal column: partition keys are a proper superset of constraint
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =);
ERROR: unique constraint on partitioned table must include all partitioning columns
DETAIL: EXCLUDE constraint on table "idxpart" lacks column "b" which is part of the partition key.
drop table idxpart;
-- Not OK with just -|-
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with -|-);
ERROR: cannot match partition key to index on column "a" using non-equal operator "-|-"
drop table idxpart;
-- OK with equals and &&, and equals is the partition key
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =, b with &&);
drop table idxpart;
-- Not OK with equals and &&, and equals is not the partition key
create table idxpart (a int4range, b int4range, c int4range) partition by range (a);
alter table idxpart add exclude USING GIST (b with =, c with &&);
ERROR: unique constraint on partitioned table must include all partitioning columns
DETAIL: EXCLUDE constraint on table "idxpart" lacks column "a" which is part of the partition key.
drop table idxpart;
-- OK more than one equal column and a && column
create table idxpart (a int4range, b int4range, c int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =, b with =, c with &&);
drop table idxpart;
-- When (sub)partitions are created, they also contain the constraint
create table idxpart (a int, b int, primary key (a, b)) partition by range (a, b);

5
src/test/regress/sql/alter_table.sql
View file

@ -2342,14 +2342,11 @@ ALTER TABLE ataddindex
\d ataddindex
DROP TABLE ataddindex;
-- unsupported constraint types for partitioned tables
-- cannot drop column that is part of the partition key
CREATE TABLE partitioned (
a int,
b int
) PARTITION BY RANGE (a, (a+b+1));
ALTER TABLE partitioned ADD EXCLUDE USING gist (a WITH &&);
-- cannot drop column that is part of the partition key
ALTER TABLE partitioned DROP COLUMN a;
ALTER TABLE partitioned ALTER COLUMN a TYPE char(5);
ALTER TABLE partitioned DROP COLUMN b;

6
src/test/regress/sql/create_table.sql
View file

@ -106,12 +106,6 @@ CREATE TABLE partitioned (
a2 int
) PARTITION BY LIST (a1, a2); -- fail
-- unsupported constraint type for partitioned tables
CREATE TABLE partitioned (
a int,
EXCLUDE USING gist (a WITH &&)
) PARTITION BY RANGE (a);
-- prevent using prohibited expressions in the key
CREATE FUNCTION retset (a int) RETURNS SETOF int AS $$ SELECT 1; $$ LANGUAGE SQL IMMUTABLE;
CREATE TABLE partitioned (

57
src/test/regress/sql/indexing.sql
View file

@ -483,8 +483,27 @@ create table idxpart (a int, b int primary key) partition by range (b, a);
create table idxpart (a int, b int, c text, primary key (a, b, c)) partition by range (b, c, a);
drop table idxpart;
-- not other types of index-based constraints
create table idxpart (a int, exclude (a with = )) partition by range (a);
-- OK to add an exclusion constraint if partitioning by its equal column
create table idxpart (a int4range, exclude USING GIST (a with = )) partition by range (a);
drop table idxpart;
-- OK more than one equal column
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with =)) partition by range (a, b);
drop table idxpart;
-- OK with more than one equal column: constraint is a proper superset of partition key
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with =)) partition by range (a);
drop table idxpart;
-- Not OK more than one equal column: partition keys are a proper superset of constraint
create table idxpart (a int4range, b int4range, exclude USING GIST (a with = )) partition by range (a, b);
-- Not OK with just -|-
create table idxpart (a int4range, exclude USING GIST (a with -|- )) partition by range (a);
-- OK with equals and &&, and equals is the partition key
create table idxpart (a int4range, b int4range, exclude USING GIST (a with =, b with &&)) partition by range (a);
drop table idxpart;
-- Not OK with equals and &&, and equals is not the partition key
create table idxpart (a int4range, b int4range, c int4range, exclude USING GIST (b with =, c with &&)) partition by range (a);
-- OK more than one equal column and a && column
create table idxpart (a int4range, b int4range, c int4range, exclude USING GIST (a with =, b with =, c with &&)) partition by range (a, b);
drop table idxpart;
-- no expressions in partition key for PK/UNIQUE
create table idxpart (a int primary key, b int) partition by range ((b + a));
@ -506,9 +525,37 @@ alter table idxpart add unique (b, a); -- this works
\d idxpart
drop table idxpart;
-- Exclusion constraints cannot be added
create table idxpart (a int, b int) partition by range (a);
alter table idxpart add exclude (a with =);
-- Exclusion constraints can be added if partitioning by their equal column
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =);
drop table idxpart;
-- OK more than one equal column
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =, b with =);
drop table idxpart;
-- OK with more than one equal column: constraint is a proper superset of partition key
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =, b with =);
drop table idxpart;
-- Not OK more than one equal column: partition keys are a proper superset of constraint
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =);
drop table idxpart;
-- Not OK with just -|-
create table idxpart (a int4range, b int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with -|-);
drop table idxpart;
-- OK with equals and &&, and equals is the partition key
create table idxpart (a int4range, b int4range) partition by range (a);
alter table idxpart add exclude USING GIST (a with =, b with &&);
drop table idxpart;
-- Not OK with equals and &&, and equals is not the partition key
create table idxpart (a int4range, b int4range, c int4range) partition by range (a);
alter table idxpart add exclude USING GIST (b with =, c with &&);
drop table idxpart;
-- OK more than one equal column and a && column
create table idxpart (a int4range, b int4range, c int4range) partition by range (a, b);
alter table idxpart add exclude USING GIST (a with =, b with =, c with &&);
drop table idxpart;
-- When (sub)partitions are created, they also contain the constraint