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Preserve replica identity index across ALTER TABLE rewrite
If an index was explicitly set as replica identity index, this setting was lost when a table was rewritten by ALTER TABLE. Because this setting is part of pg_index but actually controlled by ALTER TABLE (not part of CREATE INDEX, say), we have to do some extra work to restore it. Based-on-patch-by: Quan Zongliang <quanzongliang@gmail.com> Reviewed-by: Euler Taveira <euler.taveira@2ndquadrant.com> Discussion: https://www.postgresql.org/message-id/flat/c70fcab2-4866-0d9f-1d01-e75e189db342@gmail.com
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‎src/backend/commands/tablecmds.c

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Original file line numberDiff line numberDiff line change
@@ -176,6 +176,7 @@ typedef struct AlteredTableInfo
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List *changedConstraintDefs; /* string definitions of same */
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List *changedIndexOids; /* OIDs of indexes to rebuild */
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List *changedIndexDefs; /* string definitions of same */
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char *replicaIdentityIndex; /* index to reset as REPLICA IDENTITY */
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} AlteredTableInfo;
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/* Struct describing one new constraint to check in Phase 3 scan */
@@ -11562,6 +11563,22 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
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return address;
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}
1156411565

11566+
/*
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* Subroutine for ATExecAlterColumnType: remember that a replica identity
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* needs to be reset.
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*/
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static void
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RememberReplicaIdentityForRebuilding(Oid indoid, AlteredTableInfo *tab)
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{
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if (!get_index_isreplident(indoid))
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return;
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if (tab->replicaIdentityIndex)
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elog(ERROR, "relation %u has multiple indexes marked as replica identity", tab->relid);
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tab->replicaIdentityIndex = get_rel_name(indoid);
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}
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/*
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* Subroutine for ATExecAlterColumnType: remember that a constraint needs
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* to be rebuilt (which we might already know).
@@ -11580,11 +11597,16 @@ RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab)
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{
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/* OK, capture the constraint's existing definition string */
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char *defstring = pg_get_constraintdef_command(conoid);
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Oid indoid;
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tab->changedConstraintOids = lappend_oid(tab->changedConstraintOids,
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conoid);
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tab->changedConstraintDefs = lappend(tab->changedConstraintDefs,
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defstring);
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indoid = get_constraint_index(conoid);
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if (OidIsValid(indoid))
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RememberReplicaIdentityForRebuilding(indoid, tab);
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}
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}
1159011612

@@ -11627,6 +11649,8 @@ RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab)
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indoid);
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tab->changedIndexDefs = lappend(tab->changedIndexDefs,
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defstring);
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11653+
RememberReplicaIdentityForRebuilding(indoid, tab);
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}
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}
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}
@@ -11735,6 +11759,24 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
1173511759
add_exact_object_address(&obj, objects);
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}
1173711761

11762+
/*
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* Queue up command to restore replica identity index marking
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*/
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if (tab->replicaIdentityIndex)
11766+
{
11767+
AlterTableCmd *cmd = makeNode(AlterTableCmd);
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ReplicaIdentityStmt *subcmd = makeNode(ReplicaIdentityStmt);
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subcmd->identity_type = REPLICA_IDENTITY_INDEX;
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subcmd->name = tab->replicaIdentityIndex;
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cmd->subtype = AT_ReplicaIdentity;
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cmd->def = (Node *) subcmd;
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/* do it after indexes and constraints */
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tab->subcmds[AT_PASS_OLD_CONSTR] =
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lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
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}
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/*
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* It should be okay to use DROP_RESTRICT here, since nothing else should
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* be depending on these objects.

‎src/backend/utils/cache/lsyscache.c

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3254,6 +3254,29 @@ get_index_column_opclass(Oid index_oid, int attno)
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return opclass;
32553255
}
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/*
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* get_index_isreplident
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*
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* Given the index OID, return pg_index.indisreplident.
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*/
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bool
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get_index_isreplident(Oid index_oid)
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{
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HeapTuple tuple;
3266+
Form_pg_index rd_index;
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bool result;
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3269+
tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
3270+
if (!HeapTupleIsValid(tuple))
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return false;
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3273+
rd_index = (Form_pg_index) GETSTRUCT(tuple);
3274+
result = rd_index->indisreplident;
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ReleaseSysCache(tuple);
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3277+
return result;
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}
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32573280
/*
32583281
* get_index_isvalid
32593282
*

‎src/include/utils/lsyscache.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -182,6 +182,7 @@ extern char *get_namespace_name_or_temp(Oid nspid);
182182
extern Oid get_range_subtype(Oid rangeOid);
183183
extern Oid get_range_collation(Oid rangeOid);
184184
extern Oid get_index_column_opclass(Oid index_oid, int attno);
185+
extern bool get_index_isreplident(Oid index_oid);
185186
extern bool get_index_isvalid(Oid index_oid);
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187188
#define type_is_array(typid) (get_element_type(typid) != InvalidOid)

‎src/test/regress/expected/replica_identity.out

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -179,5 +179,51 @@ SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
179179
n
180180
(1 row)
181181

182+
---
183+
-- Test that ALTER TABLE rewrite preserves nondefault replica identity
184+
---
185+
-- constraint variant
186+
CREATE TABLE test_replica_identity2 (id int UNIQUE NOT NULL);
187+
ALTER TABLE test_replica_identity2 REPLICA IDENTITY USING INDEX test_replica_identity2_id_key;
188+
\d test_replica_identity2
189+
Table "public.test_replica_identity2"
190+
Column | Type | Collation | Nullable | Default
191+
--------+---------+-----------+----------+---------
192+
id | integer | | not null |
193+
Indexes:
194+
"test_replica_identity2_id_key" UNIQUE CONSTRAINT, btree (id) REPLICA IDENTITY
195+
196+
ALTER TABLE test_replica_identity2 ALTER COLUMN id TYPE bigint;
197+
\d test_replica_identity2
198+
Table "public.test_replica_identity2"
199+
Column | Type | Collation | Nullable | Default
200+
--------+--------+-----------+----------+---------
201+
id | bigint | | not null |
202+
Indexes:
203+
"test_replica_identity2_id_key" UNIQUE CONSTRAINT, btree (id) REPLICA IDENTITY
204+
205+
-- straight index variant
206+
CREATE TABLE test_replica_identity3 (id int NOT NULL);
207+
CREATE UNIQUE INDEX test_replica_identity3_id_key ON test_replica_identity3 (id);
208+
ALTER TABLE test_replica_identity3 REPLICA IDENTITY USING INDEX test_replica_identity3_id_key;
209+
\d test_replica_identity3
210+
Table "public.test_replica_identity3"
211+
Column | Type | Collation | Nullable | Default
212+
--------+---------+-----------+----------+---------
213+
id | integer | | not null |
214+
Indexes:
215+
"test_replica_identity3_id_key" UNIQUE, btree (id) REPLICA IDENTITY
216+
217+
ALTER TABLE test_replica_identity3 ALTER COLUMN id TYPE bigint;
218+
\d test_replica_identity3
219+
Table "public.test_replica_identity3"
220+
Column | Type | Collation | Nullable | Default
221+
--------+--------+-----------+----------+---------
222+
id | bigint | | not null |
223+
Indexes:
224+
"test_replica_identity3_id_key" UNIQUE, btree (id) REPLICA IDENTITY
225+
182226
DROP TABLE test_replica_identity;
227+
DROP TABLE test_replica_identity2;
228+
DROP TABLE test_replica_identity3;
183229
DROP TABLE test_replica_identity_othertable;

‎src/test/regress/sql/replica_identity.sql

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -75,5 +75,26 @@ SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
7575
ALTER TABLE test_replica_identity REPLICA IDENTITY NOTHING;
7676
SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
7777

78+
---
79+
-- Test that ALTER TABLE rewrite preserves nondefault replica identity
80+
---
81+
82+
-- constraint variant
83+
CREATE TABLE test_replica_identity2 (id int UNIQUE NOT NULL);
84+
ALTER TABLE test_replica_identity2 REPLICA IDENTITY USING INDEX test_replica_identity2_id_key;
85+
\d test_replica_identity2
86+
ALTER TABLE test_replica_identity2 ALTER COLUMN id TYPE bigint;
87+
\d test_replica_identity2
88+
89+
-- straight index variant
90+
CREATE TABLE test_replica_identity3 (id int NOT NULL);
91+
CREATE UNIQUE INDEX test_replica_identity3_id_key ON test_replica_identity3 (id);
92+
ALTER TABLE test_replica_identity3 REPLICA IDENTITY USING INDEX test_replica_identity3_id_key;
93+
\d test_replica_identity3
94+
ALTER TABLE test_replica_identity3 ALTER COLUMN id TYPE bigint;
95+
\d test_replica_identity3
96+
7897
DROP TABLE test_replica_identity;
98+
DROP TABLE test_replica_identity2;
99+
DROP TABLE test_replica_identity3;
79100
DROP TABLE test_replica_identity_othertable;

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