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| author | Peter Eisentraut <peter@eisentraut.org> | 2024-09-17 10:36:09 +0200 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2024-09-17 11:29:30 +0200 |
| commit | fc0438b4e80535419a4e54dba87642cdf84defda (patch) | |
| tree | b63dcc505ae98c2ef3b8143f6f38d2c0ca9b892b /src/backend/utils/cache/relcache.c | |
| parent | 7406ab623fee1addcb21c881afecbe638a0d56e9 (diff) | |
| download | postgresql-fc0438b4e80535419a4e54dba87642cdf84defda.tar.gz postgresql-fc0438b4e80535419a4e54dba87642cdf84defda.zip | |
Add temporal PRIMARY KEY and UNIQUE constraints
Add WITHOUT OVERLAPS clause to PRIMARY KEY and UNIQUE constraints.
These are backed by GiST indexes instead of B-tree indexes, since they
are essentially exclusion constraints with = for the scalar parts of
the key and && for the temporal part.
(previously committed as 46a0cd4cefb, reverted by 46a0cd4cefb; the new
part is this:)
Because 'empty' && 'empty' is false, the temporal PK/UQ constraint
allowed duplicates, which is confusing to users and breaks internal
expectations. For instance, when GROUP BY checks functional
dependencies on the PK, it allows selecting other columns from the
table, but in the presence of duplicate keys you could get the value
from any of their rows. So we need to forbid empties.
This all means that at the moment we can only support ranges and
multiranges for temporal PK/UQs, unlike the original patch (above).
Documentation and tests for this are added. But this could
conceivably be extended by introducing some more general support for
the notion of "empty" for other types.
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
Diffstat (limited to 'src/backend/utils/cache/relcache.c')
| -rw-r--r-- | src/backend/utils/cache/relcache.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 63efc55f09e..5b6b7b809c0 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -5581,11 +5581,14 @@ RelationGetIdentityKeyBitmap(Relation relation) /* * RelationGetExclusionInfo -- get info about index's exclusion constraint * - * This should be called only for an index that is known to have an - * associated exclusion constraint. It returns arrays (palloc'd in caller's - * context) of the exclusion operator OIDs, their underlying functions' - * OIDs, and their strategy numbers in the index's opclasses. We cache - * all this information since it requires a fair amount of work to get. + * This should be called only for an index that is known to have an associated + * exclusion constraint or primary key/unique constraint using WITHOUT + * OVERLAPS. + + * It returns arrays (palloc'd in caller's context) of the exclusion operator + * OIDs, their underlying functions' OIDs, and their strategy numbers in the + * index's opclasses. We cache all this information since it requires a fair + * amount of work to get. */ void RelationGetExclusionInfo(Relation indexRelation, @@ -5649,7 +5652,10 @@ RelationGetExclusionInfo(Relation indexRelation, int nelem; /* We want the exclusion constraint owning the index */ - if (conform->contype != CONSTRAINT_EXCLUSION || + if ((conform->contype != CONSTRAINT_EXCLUSION && + !(conform->conperiod && ( + conform->contype == CONSTRAINT_PRIMARY + || conform->contype == CONSTRAINT_UNIQUE))) || conform->conindid != RelationGetRelid(indexRelation)) continue; |