Support adding partitioned tables to publication

When a partitioned table is added to a publication, changes of all of
its partitions (current or future) are published via that publication.

This change only affects which tables a publication considers as its
members.  The receiving side still sees the data coming from the
individual leaf partitions.  So existing restrictions that partition
hierarchies can only be replicated one-to-one are not changed by this.

Author: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Rafia Sabih <rafia.pghackers@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+HiwqH=Y85vRK3mOdjEkqFK+E=ST=eQiHdpj43L=_eJMOOznQ@mail.gmail.com

Author: petere

doc/src/sgml/logical-replication.sgml

@@ -402,13 +402,16 @@
 
    <listitem>
     <para>
-     Replication is only possible from base tables to base tables.  That is,
-     the tables on the publication and on the subscription side must be normal
-     tables, not views, materialized views, partition root tables, or foreign
-     tables.  In the case of partitions, you can therefore replicate a
-     partition hierarchy one-to-one, but you cannot currently replicate to a
-     differently partitioned setup.  Attempts to replicate tables other than
-     base tables will result in an error.
+     Replication is only supported by tables, partitioned or not, although a
+     given table must either be partitioned on both servers or not partitioned
+     at all.  Also, when replicating between partitioned tables, the actual
+     replication occurs between leaf partitions, so partitions on the two
+     servers must match one-to-one.
+    </para>
+
+    <para>
+     Attempts to replicate other types of relations such as views, materialized
+     views, or foreign tables, will result in an error.
     </para>
    </listitem>
   </itemizedlist>

doc/src/sgml/ref/create_publication.sgml

@@ -69,14 +69,23 @@ CREATE PUBLICATION <replaceable class="parameter">name</replaceable>
       specified, the table and all its descendant tables (if any) are added.
       Optionally, <literal>*</literal> can be specified after the table name to
       explicitly indicate that descendant tables are included.
+      This does not apply to a partitioned table, however.  The partitions of
+      a partitioned table are always implicitly considered part of the
+      publication, so they are never explicitly added to the publication.
      </para>
 
      <para>
-      Only persistent base tables can be part of a publication.  Temporary
-      tables, unlogged tables, foreign tables, materialized views, regular
-      views, and partitioned tables cannot be part of a publication.  To
-      replicate a partitioned table, add the individual partitions to the
-      publication.
+      Only persistent base tables and partitioned tables can be part of a
+      publication.  Temporary tables, unlogged tables, foreign tables,
+      materialized views, and regular views cannot be part of a publication.
+     </para>
+
+     <para>
+      When a partitioned table is added to a publication, all of its existing
+      and future partitions are implicitly considered to be part of the
+      publication.  So, even operations that are performed directly on a
+      partition are also published via publications that its ancestors are
+      part of.
      </para>
     </listitem>
    </varlistentry>

src/backend/catalog/pg_publication.c

@@ -24,8 +24,10 @@
 #include "catalog/index.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
+#include "catalog/partition.h"
 #include "catalog/objectaccess.h"
 #include "catalog/objectaddress.h"
+#include "catalog/pg_inherits.h"
 #include "catalog/pg_publication.h"
 #include "catalog/pg_publication_rel.h"
 #include "catalog/pg_type.h"
@@ -40,24 +42,18 @@
 #include "utils/rel.h"
 #include "utils/syscache.h"
 
+static List *get_rel_publications(Oid relid);
+
 /*
  * Check if relation can be in given publication and throws appropriate
  * error if not.
  */
 static void
 check_publication_add_relation(Relation targetrel)
 {
-	/* Give more specific error for partitioned tables */
-	if (RelationGetForm(targetrel)->relkind == RELKIND_PARTITIONED_TABLE)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("\"%s\" is a partitioned table",
-						RelationGetRelationName(targetrel)),
-				 errdetail("Adding partitioned tables to publications is not supported."),
-				 errhint("You can add the table partitions individually.")));
-
-	/* Must be table */
-	if (RelationGetForm(targetrel)->relkind != RELKIND_RELATION)
+	/* Must be a regular or partitioned table */
+	if (RelationGetForm(targetrel)->relkind != RELKIND_RELATION &&
+		RelationGetForm(targetrel)->relkind != RELKIND_PARTITIONED_TABLE)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("\"%s\" is not a table",
@@ -103,7 +99,8 @@ check_publication_add_relation(Relation targetrel)
 static bool
 is_publishable_class(Oid relid, Form_pg_class reltuple)
 {
-	return reltuple->relkind == RELKIND_RELATION &&
+	return (reltuple->relkind == RELKIND_RELATION ||
+			reltuple->relkind == RELKIND_PARTITIONED_TABLE) &&
 		!IsCatalogRelationOid(relid) &&
 		reltuple->relpersistence == RELPERSISTENCE_PERMANENT &&
 		relid >= FirstNormalObjectId;
@@ -221,10 +218,35 @@ publication_add_relation(Oid pubid, Relation targetrel,
 
 
 /*
- * Gets list of publication oids for a relation oid.
+ * Gets list of publication oids for a relation, plus those of ancestors,
+ * if any, if the relation is a partition.
  */
 List *
 GetRelationPublications(Oid relid)
+{
+	List	   *result = NIL;
+
+	result = get_rel_publications(relid);
+	if (get_rel_relispartition(relid))
+	{
+		List	   *ancestors = get_partition_ancestors(relid);
+		ListCell   *lc;
+
+		foreach(lc, ancestors)
+		{
+			Oid			ancestor = lfirst_oid(lc);
+			List	   *ancestor_pubs = get_rel_publications(ancestor);
+
+			result = list_concat(result, ancestor_pubs);
+		}
+	}
+
+	return result;
+}
+
+/* Workhorse of GetRelationPublications() */
+static List *
+get_rel_publications(Oid relid)
 {
 	List	   *result = NIL;
 	CatCList   *pubrellist;
@@ -253,7 +275,7 @@ GetRelationPublications(Oid relid)
  * should use GetAllTablesPublicationRelations().
  */
 List *
-GetPublicationRelations(Oid pubid)
+GetPublicationRelations(Oid pubid, PublicationPartOpt pub_partopt)
 {
 	List	   *result;
 	Relation	pubrelsrel;
@@ -279,7 +301,31 @@ GetPublicationRelations(Oid pubid)
 
 		pubrel = (Form_pg_publication_rel) GETSTRUCT(tup);
 
-		result = lappend_oid(result, pubrel->prrelid);
+		if (get_rel_relkind(pubrel->prrelid) == RELKIND_PARTITIONED_TABLE &&
+			pub_partopt != PUBLICATION_PART_ROOT)
+		{
+			List	   *all_parts = find_all_inheritors(pubrel->prrelid, NoLock,
+														NULL);
+
+			if (pub_partopt == PUBLICATION_PART_ALL)
+				result = list_concat(result, all_parts);
+			else if (pub_partopt == PUBLICATION_PART_LEAF)
+			{
+				ListCell   *lc;
+
+				foreach(lc, all_parts)
+				{
+					Oid			partOid = lfirst_oid(lc);
+
+					if (get_rel_relkind(partOid) != RELKIND_PARTITIONED_TABLE)
+						result = lappend_oid(result, partOid);
+				}
+			}
+			else
+				Assert(false);
+		}
+		else
+			result = lappend_oid(result, pubrel->prrelid);
 	}
 
 	systable_endscan(scan);
@@ -480,10 +526,17 @@ pg_get_publication_tables(PG_FUNCTION_ARGS)
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
 		publication = GetPublicationByName(pubname, false);
+
+		/*
+		 * Publications support partitioned tables, although all changes are
+		 * replicated using leaf partition identity and schema, so we only
+		 * need those.
+		 */
 		if (publication->alltables)
 			tables = GetAllTablesPublicationRelations();
 		else
-			tables = GetPublicationRelations(publication->oid);
+			tables = GetPublicationRelations(publication->oid,
+											 PUBLICATION_PART_LEAF);
 		funcctx->user_fctx = (void *) tables;
 
 		MemoryContextSwitchTo(oldcontext);

src/backend/commands/publicationcmds.c

@@ -299,7 +299,13 @@ AlterPublicationOptions(AlterPublicationStmt *stmt, Relation rel,
 	}
 	else
 	{
-		List	   *relids = GetPublicationRelations(pubform->oid);
+		/*
+		 * For any partitioned tables contained in the publication, we must
+		 * invalidate all partitions contained in the respective partition
+		 * trees, not just those explicitly mentioned in the publication.
+		 */
+		List   *relids = GetPublicationRelations(pubform->oid,
+												 PUBLICATION_PART_ALL);
 
 		/*
 		 * We don't want to send too many individual messages, at some point
@@ -356,7 +362,8 @@ AlterPublicationTables(AlterPublicationStmt *stmt, Relation rel,
 		PublicationDropTables(pubid, rels, false);
 	else						/* DEFELEM_SET */
 	{
-		List	   *oldrelids = GetPublicationRelations(pubid);
+		List   *oldrelids = GetPublicationRelations(pubid,
+													PUBLICATION_PART_ROOT);
 		List	   *delrels = NIL;
 		ListCell   *oldlc;
 
@@ -498,7 +505,8 @@ RemovePublicationRelById(Oid proid)
 
 /*
  * Open relations specified by a RangeVar list.
- * The returned tables are locked in ShareUpdateExclusiveLock mode.
+ * The returned tables are locked in ShareUpdateExclusiveLock mode in order to
+ * add them to a publication.
  */
 static List *
 OpenTableList(List *tables)
@@ -539,8 +547,13 @@ OpenTableList(List *tables)
 		rels = lappend(rels, rel);
 		relids = lappend_oid(relids, myrelid);
 
-		/* Add children of this rel, if requested */
-		if (recurse)
+		/*
+		 * Add children of this rel, if requested, so that they too are added
+		 * to the publication.  A partitioned table can't have any inheritance
+		 * children other than its partitions, which need not be explicitly
+		 * added to the publication.
+		 */
+		if (recurse && rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
 		{
 			List	   *children;
 			ListCell   *child;

src/backend/replication/logical/tablesync.c

@@ -761,6 +761,7 @@ copy_table(Relation rel)
 	/* Map the publisher relation to local one. */
 	relmapentry = logicalrep_rel_open(lrel.remoteid, NoLock);
 	Assert(rel == relmapentry->localrel);
+	Assert(relmapentry->localrel->rd_rel->relkind == RELKIND_RELATION);
 
 	/* Start copy on the publisher. */
 	initStringInfo(&cmd);

src/backend/replication/pgoutput/pgoutput.c

@@ -50,7 +50,12 @@ static List *LoadPublications(List *pubnames);
 static void publication_invalidation_cb(Datum arg, int cacheid,
 										uint32 hashvalue);
 
-/* Entry in the map used to remember which relation schemas we sent. */
+/*
+ * Entry in the map used to remember which relation schemas we sent.
+ *
+ * For partitions, 'pubactions' considers not only the table's own
+ * publications, but also those of all of its ancestors.
+ */
 typedef struct RelationSyncEntry
 {
 	Oid			relid;			/* relation oid */
@@ -406,6 +411,13 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 		if (!relentry->pubactions.pubtruncate)
 			continue;
 
+		/*
+		 * Don't send partitioned tables, because partitions should be sent
+		 * instead.
+		 */
+		if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+			continue;
+
 		relids[nrelids++] = relid;
 		maybe_send_schema(ctx, relation, relentry);
 	}
@@ -524,6 +536,11 @@ init_rel_sync_cache(MemoryContext cachectx)
 
 /*
  * Find or create entry in the relation schema cache.
+ *
+ * This looks up publications that the given relation is directly or
+ * indirectly part of (the latter if it's really the relation's ancestor that
+ * is part of a publication) and fills up the found entry with the information
+ * about which operations to publish.
  */
 static RelationSyncEntry *
 get_rel_sync_entry(PGOutputData *data, Oid relid)

src/bin/pg_dump/pg_dump.c

@@ -3981,8 +3981,12 @@ getPublicationTables(Archive *fout, TableInfo tblinfo[], int numTables)
 	{
 		TableInfo  *tbinfo = &tblinfo[i];
 
-		/* Only plain tables can be aded to publications. */
-		if (tbinfo->relkind != RELKIND_RELATION)
+		/*
+		 * Only regular and partitioned tables can be added to
+		 * publications.
+		 */
+		if (tbinfo->relkind != RELKIND_RELATION &&
+			tbinfo->relkind != RELKIND_PARTITIONED_TABLE)
 			continue;
 
 		/*

src/include/catalog/pg_publication.h

@@ -80,7 +80,24 @@ typedef struct Publication
 extern Publication *GetPublication(Oid pubid);
 extern Publication *GetPublicationByName(const char *pubname, bool missing_ok);
 extern List *GetRelationPublications(Oid relid);
-extern List *GetPublicationRelations(Oid pubid);
+
+/*---------
+ * Expected values for pub_partopt parameter of GetRelationPublications(),
+ * which allows callers to specify which partitions of partitioned tables
+ * mentioned in the publication they expect to see.
+ *
+ *	ROOT:	only the table explicitly mentioned in the publication
+ *	LEAF:	only leaf partitions in given tree
+ *	ALL:	all partitions in given tree
+ */
+typedef enum PublicationPartOpt
+{
+	PUBLICATION_PART_ROOT,
+	PUBLICATION_PART_LEAF,
+	PUBLICATION_PART_ALL,
+}			PublicationPartOpt;
+
+extern List *GetPublicationRelations(Oid pubid, PublicationPartOpt pub_partopt);
 extern List *GetAllTablesPublications(void);
 extern List *GetAllTablesPublicationRelations(void);
 

src/test/regress/expected/publication.out

@@ -116,6 +116,35 @@ Tables:
 
 DROP TABLE testpub_tbl3, testpub_tbl3a;
 DROP PUBLICATION testpub3, testpub4;
+-- Tests for partitioned tables
+SET client_min_messages = 'ERROR';
+CREATE PUBLICATION testpub_forparted;
+CREATE PUBLICATION testpub_forparted1;
+RESET client_min_messages;
+CREATE TABLE testpub_parted1 (LIKE testpub_parted);
+ALTER PUBLICATION testpub_forparted1 SET (publish='insert');
+-- works despite missing REPLICA IDENTITY, because updates are not replicated
+UPDATE testpub_parted1 SET a = 1;
+ALTER TABLE testpub_parted ATTACH PARTITION testpub_parted1 FOR VALUES IN (1);
+-- only parent is listed as being in publication, not the partition
+ALTER PUBLICATION testpub_forparted ADD TABLE testpub_parted;
+\dRp+ testpub_forparted
+                          Publication testpub_forparted
+          Owner           | All tables | Inserts | Updates | Deletes | Truncates 
+--------------------------+------------+---------+---------+---------+-----------
+ regress_publication_user | f          | t       | t       | t       | t
+Tables:
+    "public.testpub_parted"
+
+-- should now fail, because parent's publication replicates updates
+UPDATE testpub_parted1 SET a = 1;
+ERROR:  cannot update table "testpub_parted1" because it does not have a replica identity and publishes updates
+HINT:  To enable updating the table, set REPLICA IDENTITY using ALTER TABLE.
+ALTER TABLE testpub_parted DETACH PARTITION testpub_parted1;
+-- works again, because parent's publication is no longer considered
+UPDATE testpub_parted1 SET a = 1;
+DROP TABLE testpub_parted1;
+DROP PUBLICATION testpub_forparted, testpub_forparted1;
 -- fail - view
 CREATE PUBLICATION testpub_fortbl FOR TABLE testpub_view;
 ERROR:  "testpub_view" is not a table
@@ -142,11 +171,6 @@ Tables:
 ALTER PUBLICATION testpub_default ADD TABLE testpub_view;
 ERROR:  "testpub_view" is not a table
 DETAIL:  Only tables can be added to publications.
--- fail - partitioned table
-ALTER PUBLICATION testpub_fortbl ADD TABLE testpub_parted;
-ERROR:  "testpub_parted" is a partitioned table
-DETAIL:  Adding partitioned tables to publications is not supported.
-HINT:  You can add the table partitions individually.
 ALTER PUBLICATION testpub_default ADD TABLE testpub_tbl1;
 ALTER PUBLICATION testpub_default SET TABLE testpub_tbl1;
 ALTER PUBLICATION testpub_default ADD TABLE pub_test.testpub_nopk;