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

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 7fcc3db14cb5f76e9a2e7dcec899cfe88d323ed8..820041175221d80e40d1d9f2ee7ba5ae4a4e0dc2 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -166,6 +166,7 @@ typedef struct AlteredTableInfo
    List       *changedConstraintDefs;  /* string definitions of same */
    List       *changedIndexOids;       /* OIDs of indexes to rebuild */
    List       *changedIndexDefs;       /* string definitions of same */
+   char       *replicaIdentityIndex;   /* index to reset as REPLICA IDENTITY */
 } AlteredTableInfo;
 
 /* Struct describing one new constraint to check in Phase 3 scan */
@@ -8566,6 +8567,22 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
    return address;
 }
 
+/*
+ * Subroutine for ATExecAlterColumnType: remember that a replica identity
+ * needs to be reset.
+ */
+static void
+RememberReplicaIdentityForRebuilding(Oid indoid, AlteredTableInfo *tab)
+{
+   if (!get_index_isreplident(indoid))
+       return;
+
+   if (tab->replicaIdentityIndex)
+       elog(ERROR, "relation %u has multiple indexes marked as replica identity", tab->relid);
+
+   tab->replicaIdentityIndex = get_rel_name(indoid);
+}
+
 /*
  * Subroutine for ATExecAlterColumnType: remember that a constraint needs
  * to be rebuilt (which we might already know).
@@ -8585,6 +8602,7 @@ RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab,
    {
        /* OK, capture the constraint's existing definition string */
        char       *defstring = pg_get_constraintdef_command(conoid);
+       Oid         indoid;
 
        /*
         * Put NORMAL dependencies at the front of the list and AUTO
@@ -8608,6 +8626,10 @@ RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab,
            tab->changedConstraintDefs = lappend(tab->changedConstraintDefs,
                                                 defstring);
        }
+
+       indoid = get_constraint_index(conoid);
+       if (OidIsValid(indoid))
+           RememberReplicaIdentityForRebuilding(indoid, tab);
    }
 }
 
@@ -8651,6 +8673,8 @@ RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab)
                                                indoid);
            tab->changedIndexDefs = lappend(tab->changedIndexDefs,
                                            defstring);
+
+           RememberReplicaIdentityForRebuilding(indoid, tab);
        }
    }
 }
@@ -8844,6 +8868,24 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
                             wqueue, lockmode, tab->rewrite);
    }
 
+   /*
+    * Queue up command to restore replica identity index marking
+    */
+   if (tab->replicaIdentityIndex)
+   {
+       AlterTableCmd *cmd = makeNode(AlterTableCmd);
+       ReplicaIdentityStmt *subcmd = makeNode(ReplicaIdentityStmt);
+
+       subcmd->identity_type = REPLICA_IDENTITY_INDEX;
+       subcmd->name = tab->replicaIdentityIndex;
+       cmd->subtype = AT_ReplicaIdentity;
+       cmd->def = (Node *) subcmd;
+
+       /* do it after indexes and constraints */
+       tab->subcmds[AT_PASS_OLD_CONSTR] =
+           lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
+   }
+
    /*
     * Now we can drop the existing constraints and indexes --- constraints
     * first, since some of them might depend on the indexes.  In fact, we

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index b0b024dc3ed9674c5c1305e6b34d21c0275134ce..49bf69a82fd3b8932ea86277d421242c0a6e7887 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -3045,3 +3045,28 @@ get_range_collation(Oid rangeOid)
    else
        return InvalidOid;
 }
+
+/*             ---------- PG_INDEX CACHE ----------                 */
+
+/*
+ * get_index_isreplident
+ *
+ *     Given the index OID, return pg_index.indisreplident.
+ */
+bool
+get_index_isreplident(Oid index_oid)
+{
+   HeapTuple       tuple;
+   Form_pg_index   rd_index;
+   bool            result;
+
+   tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
+   if (!HeapTupleIsValid(tuple))
+       return false;
+
+   rd_index = (Form_pg_index) GETSTRUCT(tuple);
+   result = rd_index->indisreplident;
+   ReleaseSysCache(tuple);
+
+   return result;
+}

diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 489b196ecf4f505c5dc8738186c52a29d6886b8f..f01934afa143bbe0deede487aa1479d43e2c2403 100644 (file)
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -158,6 +158,7 @@ extern char *get_namespace_name(Oid nspid);
 extern char *get_namespace_name_or_temp(Oid nspid);
 extern Oid get_range_subtype(Oid rangeOid);
 extern Oid get_range_collation(Oid rangeOid);
+extern bool    get_index_isreplident(Oid index_oid);
 
 #define type_is_array(typid)  (get_element_type(typid) != InvalidOid)
 /* type_is_array_domain accepts both plain arrays and domains over arrays */

diff --git a/src/test/regress/expected/replica_identity.out b/src/test/regress/expected/replica_identity.out
index 0da54a0544738e123999b483768fe2b5925e75cd..332f30141319de9b567b7a99076e08b7161a0da9 100644 (file)
--- a/src/test/regress/expected/replica_identity.out
+++ b/src/test/regress/expected/replica_identity.out
@@ -187,5 +187,51 @@ SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
  n
 (1 row)
 
+---
+-- Test that ALTER TABLE rewrite preserves nondefault replica identity
+---
+-- constraint variant
+CREATE TABLE test_replica_identity2 (id int UNIQUE NOT NULL);
+ALTER TABLE test_replica_identity2 REPLICA IDENTITY USING INDEX test_replica_identity2_id_key;
+\d test_replica_identity2
+Table "public.test_replica_identity2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ id     | integer | not null
+Indexes:
+    "test_replica_identity2_id_key" UNIQUE CONSTRAINT, btree (id) REPLICA IDENTITY
+
+ALTER TABLE test_replica_identity2 ALTER COLUMN id TYPE bigint;
+\d test_replica_identity2
+Table "public.test_replica_identity2"
+ Column |  Type  | Modifiers 
+--------+--------+-----------
+ id     | bigint | not null
+Indexes:
+    "test_replica_identity2_id_key" UNIQUE CONSTRAINT, btree (id) REPLICA IDENTITY
+
+-- straight index variant
+CREATE TABLE test_replica_identity3 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_identity3_id_key ON test_replica_identity3 (id);
+ALTER TABLE test_replica_identity3 REPLICA IDENTITY USING INDEX test_replica_identity3_id_key;
+\d test_replica_identity3
+Table "public.test_replica_identity3"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ id     | integer | not null
+Indexes:
+    "test_replica_identity3_id_key" UNIQUE, btree (id) REPLICA IDENTITY
+
+ALTER TABLE test_replica_identity3 ALTER COLUMN id TYPE bigint;
+\d test_replica_identity3
+Table "public.test_replica_identity3"
+ Column |  Type  | Modifiers 
+--------+--------+-----------
+ id     | bigint | not null
+Indexes:
+    "test_replica_identity3_id_key" UNIQUE, btree (id) REPLICA IDENTITY
+
 DROP TABLE test_replica_identity;
+DROP TABLE test_replica_identity2;
+DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;

diff --git a/src/test/regress/sql/replica_identity.sql b/src/test/regress/sql/replica_identity.sql
index bb71fdac96ba8a5f54aab33fd89ff2ada93fe69a..ab4c72b23a0565274f63fb9ae654d2ab2c70090d 100644 (file)
--- a/src/test/regress/sql/replica_identity.sql
+++ b/src/test/regress/sql/replica_identity.sql
@@ -79,5 +79,26 @@ SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
 ALTER TABLE test_replica_identity REPLICA IDENTITY NOTHING;
 SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity'::regclass;
 
+---
+-- Test that ALTER TABLE rewrite preserves nondefault replica identity
+---
+
+-- constraint variant
+CREATE TABLE test_replica_identity2 (id int UNIQUE NOT NULL);
+ALTER TABLE test_replica_identity2 REPLICA IDENTITY USING INDEX test_replica_identity2_id_key;
+\d test_replica_identity2
+ALTER TABLE test_replica_identity2 ALTER COLUMN id TYPE bigint;
+\d test_replica_identity2
+
+-- straight index variant
+CREATE TABLE test_replica_identity3 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_identity3_id_key ON test_replica_identity3 (id);
+ALTER TABLE test_replica_identity3 REPLICA IDENTITY USING INDEX test_replica_identity3_id_key;
+\d test_replica_identity3
+ALTER TABLE test_replica_identity3 ALTER COLUMN id TYPE bigint;
+\d test_replica_identity3
+
 DROP TABLE test_replica_identity;
+DROP TABLE test_replica_identity2;
+DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;