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 1a005760d8660408c6fa212553b4bf2a15003a85..e99e16efbc06a4044f0b66fe8117c912c004c957 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -173,6 +173,7 @@ 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 */
@@ -9420,6 +9421,22 @@ 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).
@@ -9439,6 +9456,7 @@ 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
@@ -9462,6 +9480,10 @@ RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab,
                        tab->changedConstraintDefs = lappend(tab->changedConstraintDefs,
                                                                                                 defstring);
                }
+
+               indoid = get_constraint_index(conoid);
+               if (OidIsValid(indoid))
+                       RememberReplicaIdentityForRebuilding(indoid, tab);
        }
 }
 
@@ -9505,6 +9527,8 @@ RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab)
                                                                                                indoid);
                        tab->changedIndexDefs = lappend(tab->changedIndexDefs,
                                                                                        defstring);
+
+                       RememberReplicaIdentityForRebuilding(indoid, tab);
                }
        }
 }
@@ -9697,6 +9721,24 @@ 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 88415e6892d6704deeeec10b39f9d5e613b97248..db62daf77eccb425661ec9b9b575b982ccbd6eb5 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -3138,3 +3138,28 @@ 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 e9ef5cba341c3bf9f05dcf36b620092503af8694..770972a2818340f70aca69b7f132a38bce3141c7 100644 (file)
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -178,6 +178,7 @@ 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 67c34a92a4ea87ff1b2ff51983e12a13f605d457..65c7c9ac9f803ffabc55dd3a2ba54dba3e1f0dd3 100644 (file)
--- a/src/test/regress/expected/replica_identity.out
+++ b/src/test/regress/expected/replica_identity.out
@@ -186,5 +186,51 @@ 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   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ 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  | Collation | Nullable | Default 
+--------+--------+-----------+----------+---------
+ 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   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ 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  | Collation | Nullable | Default 
+--------+--------+-----------+----------+---------
+ 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 3d2171c73367439462151a5cb36fd3079f84c614..5277ff39cd3913960f1c4781af0436b001d0eb7b 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;