database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-26 01:22:12 +03:00
Code Activity

Allow the use of a hash index on the subscriber during replication.

Browse Source 
Commit 89e46da5e5 allowed using BTREE indexes that are neither
PRIMARY KEY nor REPLICA IDENTITY on the subscriber during apply of
update/delete. This patch extends that functionality to also allow HASH
indexes.

We explored supporting other index access methods as well but they don't
have a fixed strategy for equality operation which is required by the
current infrastructure in logical replication to scan the indexes.

Author: Kuroda Hayato
Reviewed-by: Peter Smith, Onder Kalaci, Amit Kapila
Discussion: https://postgr.es/m/TYAPR01MB58669D7414E59664E17A5827F522A@TYAPR01MB5866.jpnprd01.prod.outlook.com
This commit is contained in:
Amit Kapila
2023-07-14 08:21:54 +05:30
parent a5ea825f95
commit edca342434
7 changed files with 186 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
src/backend/replication/logical/relation.c
View File

@ -17,6 +17,9 @@
#include "postgres.h"
#ifdef USE_ASSERT_CHECKING
#include "access/amapi.h"
#endif
#include "access/genam.h"
#include "access/table.h"
#include "catalog/namespace.h"
@ -779,7 +782,7 @@ RemoteRelContainsLeftMostColumnOnIdx(IndexInfo *indexInfo, AttrMap *attrmap)
/*
* Returns the oid of an index that can be used by the apply worker to scan
* the relation. The index must be btree, non-partial, and the leftmost
* the relation. The index must be btree or hash, non-partial, and the leftmost
* field must be a column (not an expression) that references the remote
* relation column. These limitations help to keep the index scan similar
* to PK/RI index scans.
@ -791,11 +794,11 @@ RemoteRelContainsLeftMostColumnOnIdx(IndexInfo *indexInfo, AttrMap *attrmap)
* compare the tuples for non-PK/RI index scans. See
* RelationFindReplTupleByIndex().
*
* XXX: There are no fundamental problems for supporting non-btree indexes.
* We mostly need to relax the limitations in RelationFindReplTupleByIndex().
* For partial indexes, the required changes are likely to be larger. If
* none of the tuples satisfy the expression for the index scan, we fall-back
* to sequential execution, which might not be a good idea in some cases.
* XXX: See IsIndexUsableForReplicaIdentityFull() to know the challenges in
* supporting indexes other than btree and hash. For partial indexes, the
* required changes are likely to be larger. If none of the tuples satisfy
* the expression for the index scan, we fall-back to sequential execution,
* which might not be a good idea in some cases.
*
* We expect to call this function when REPLICA IDENTITY FULL is defined for
* the remote relation.
@ -834,15 +837,43 @@ FindUsableIndexForReplicaIdentityFull(Relation localrel, AttrMap *attrmap)
/*
* Returns true if the index is usable for replica identity full. For details,
* see FindUsableIndexForReplicaIdentityFull.
*
* Currently, only Btree and Hash indexes can be returned as usable. This
* is due to following reasons:
*
* 1) Other index access methods don't have a fixed strategy for equality
* operation. Refer get_equal_strategy_number_for_am().
*
* 2) For indexes other than PK and REPLICA IDENTITY, we need to match the
* local and remote tuples. The equality routine tuples_equal() cannot accept
* a datatype (e.g. point or box) that does not have a default operator class
* for Btree or Hash.
*
* XXX: Note that BRIN and GIN indexes do not implement "amgettuple" which
* will be used later to fetch the tuples. See RelationFindReplTupleByIndex().
*/
bool
IsIndexUsableForReplicaIdentityFull(IndexInfo *indexInfo)
{
bool is_btree = (indexInfo->ii_Am == BTREE_AM_OID);
bool is_partial = (indexInfo->ii_Predicate != NIL);
bool is_only_on_expression = IsIndexOnlyOnExpression(indexInfo);
/* Ensure that the index access method has a valid equal strategy */
if (get_equal_strategy_number_for_am(indexInfo->ii_Am) == InvalidStrategy)
return false;
if (indexInfo->ii_Predicate != NIL)
return false;
if (IsIndexOnlyOnExpression(indexInfo))
return false;
return is_btree && !is_partial && !is_only_on_expression;
#ifdef USE_ASSERT_CHECKING
{
IndexAmRoutine *amroutine;
/* The given index access method must implement amgettuple. */
amroutine = GetIndexAmRoutineByAmId(indexInfo->ii_Am, false);
Assert(amroutine->amgettuple != NULL);
}
#endif
return true;
}
/*