Add logical replication support to replicate into partitioned tables

Mainly, this adds support code in logical/worker.c for applying
replicated operations whose target is a partitioned table to its
relevant partitions.

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

src/backend/executor/execReplication.c

@@ -594,17 +594,9 @@ CheckSubscriptionRelkind(char relkind, const char *nspname,
 						 const char *relname)
 {
 	/*
-	 * We currently only support writing to regular tables.  However, give a
-	 * more specific error for partitioned and foreign tables.
+	 * Give a more specific error for foreign tables.
 	 */
-	if (relkind == RELKIND_PARTITIONED_TABLE)
-		ereport(ERROR,
-				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("cannot use relation \"%s.%s\" as logical replication target",
-						nspname, relname),
-				 errdetail("\"%s.%s\" is a partitioned table.",
-						   nspname, relname)));
-	else if (relkind == RELKIND_FOREIGN_TABLE)
+	if (relkind == RELKIND_FOREIGN_TABLE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("cannot use relation \"%s.%s\" as logical replication target",
@@ -612,7 +604,7 @@ CheckSubscriptionRelkind(char relkind, const char *nspname,
 				 errdetail("\"%s.%s\" is a foreign table.",
 						   nspname, relname)));
 
-	if (relkind != RELKIND_RELATION)
+	if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("cannot use relation \"%s.%s\" as logical replication target",

src/backend/replication/logical/relation.c

@@ -35,6 +35,24 @@ static MemoryContext LogicalRepRelMapContext = NULL;
 static HTAB *LogicalRepRelMap = NULL;
 static HTAB *LogicalRepTypMap = NULL;
 
+/*
+ * Partition map (LogicalRepPartMap)
+ *
+ * When a partitioned table is used as replication target, replicated
+ * operations are actually performed on its leaf partitions, which requires
+ * the partitions to also be mapped to the remote relation.  Parent's entry
+ * (LogicalRepRelMapEntry) cannot be used as-is for all partitions, because
+ * individual partitions may have different attribute numbers, which means
+ * attribute mappings to remote relation's attributes must be maintained
+ * separately for each partition.
+ */
+static MemoryContext LogicalRepPartMapContext = NULL;
+static HTAB *LogicalRepPartMap = NULL;
+typedef struct LogicalRepPartMapEntry
+{
+	Oid			partoid;		/* LogicalRepPartMap's key */
+	LogicalRepRelMapEntry relmapentry;
+}			LogicalRepPartMapEntry;
 
 /*
  * Relcache invalidation callback for our relation map cache.
@@ -472,3 +490,174 @@ logicalrep_typmap_gettypname(Oid remoteid)
 	Assert(OidIsValid(entry->remoteid));
 	return psprintf("%s.%s", entry->nspname, entry->typname);
 }
+
+/*
+ * Partition cache: look up partition LogicalRepRelMapEntry's
+ *
+ * Unlike relation map cache, this is keyed by partition OID, not remote
+ * relation OID, because we only have to use this cache in the case where
+ * partitions are not directly mapped to any remote relation, such as when
+ * replication is occurring with one of their ancestors as target.
+ */
+
+/*
+ * Relcache invalidation callback
+ */
+static void
+logicalrep_partmap_invalidate_cb(Datum arg, Oid reloid)
+{
+	LogicalRepRelMapEntry *entry;
+
+	/* Just to be sure. */
+	if (LogicalRepPartMap == NULL)
+		return;
+
+	if (reloid != InvalidOid)
+	{
+		HASH_SEQ_STATUS status;
+
+		hash_seq_init(&status, LogicalRepPartMap);
+
+		/* TODO, use inverse lookup hashtable? */
+		while ((entry = (LogicalRepRelMapEntry *) hash_seq_search(&status)) != NULL)
+		{
+			if (entry->localreloid == reloid)
+			{
+				entry->localreloid = InvalidOid;
+				hash_seq_term(&status);
+				break;
+			}
+		}
+	}
+	else
+	{
+		/* invalidate all cache entries */
+		HASH_SEQ_STATUS status;
+
+		hash_seq_init(&status, LogicalRepPartMap);
+
+		while ((entry = (LogicalRepRelMapEntry *) hash_seq_search(&status)) != NULL)
+			entry->localreloid = InvalidOid;
+	}
+}
+
+/*
+ * Initialize the partition map cache.
+ */
+static void
+logicalrep_partmap_init(void)
+{
+	HASHCTL		ctl;
+
+	if (!LogicalRepPartMapContext)
+		LogicalRepPartMapContext =
+			AllocSetContextCreate(CacheMemoryContext,
+								  "LogicalRepPartMapContext",
+								  ALLOCSET_DEFAULT_SIZES);
+
+	/* Initialize the relation hash table. */
+	MemSet(&ctl, 0, sizeof(ctl));
+	ctl.keysize = sizeof(Oid);	/* partition OID */
+	ctl.entrysize = sizeof(LogicalRepPartMapEntry);
+	ctl.hcxt = LogicalRepPartMapContext;
+
+	LogicalRepPartMap = hash_create("logicalrep partition map cache", 64, &ctl,
+									HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+
+	/* Watch for invalidation events. */
+	CacheRegisterRelcacheCallback(logicalrep_partmap_invalidate_cb,
+								  (Datum) 0);
+}
+
+/*
+ * logicalrep_partition_open
+ *
+ * Returned entry reuses most of the values of the root table's entry, save
+ * the attribute map, which can be different for the partition.
+ *
+ * Note there's no logialrep_partition_close, because the caller closes the
+ * the component relation.
+ */
+LogicalRepRelMapEntry *
+logicalrep_partition_open(LogicalRepRelMapEntry *root,
+						  Relation partrel, AttrMap *map)
+{
+	LogicalRepRelMapEntry *entry;
+	LogicalRepPartMapEntry *part_entry;
+	LogicalRepRelation *remoterel = &root->remoterel;
+	Oid			partOid = RelationGetRelid(partrel);
+	AttrMap    *attrmap = root->attrmap;
+	bool		found;
+	int			i;
+	MemoryContext oldctx;
+
+	if (LogicalRepPartMap == NULL)
+		logicalrep_partmap_init();
+
+	/* Search for existing entry. */
+	part_entry = (LogicalRepPartMapEntry *) hash_search(LogicalRepPartMap,
+														(void *) &partOid,
+														HASH_ENTER, &found);
+
+	if (found)
+		return &part_entry->relmapentry;
+
+	memset(part_entry, 0, sizeof(LogicalRepPartMapEntry));
+
+	/* Switch to longer-lived context. */
+	oldctx = MemoryContextSwitchTo(LogicalRepPartMapContext);
+
+	part_entry->partoid = partOid;
+
+	/* Remote relation is used as-is from the root entry. */
+	entry = &part_entry->relmapentry;
+	entry->remoterel.remoteid = remoterel->remoteid;
+	entry->remoterel.nspname = pstrdup(remoterel->nspname);
+	entry->remoterel.relname = pstrdup(remoterel->relname);
+	entry->remoterel.natts = remoterel->natts;
+	entry->remoterel.attnames = palloc(remoterel->natts * sizeof(char *));
+	entry->remoterel.atttyps = palloc(remoterel->natts * sizeof(Oid));
+	for (i = 0; i < remoterel->natts; i++)
+	{
+		entry->remoterel.attnames[i] = pstrdup(remoterel->attnames[i]);
+		entry->remoterel.atttyps[i] = remoterel->atttyps[i];
+	}
+	entry->remoterel.replident = remoterel->replident;
+	entry->remoterel.attkeys = bms_copy(remoterel->attkeys);
+
+	entry->localrel = partrel;
+	entry->localreloid = partOid;
+
+	/*
+	 * If the partition's attributes don't match the root relation's, we'll
+	 * need to make a new attrmap which maps partition attribute numbers to
+	 * remoterel's, instead the original which maps root relation's attribute
+	 * numbers to remoterel's.
+	 *
+	 * Note that 'map' which comes from the tuple routing data structure
+	 * contains 1-based attribute numbers (of the parent relation).  However,
+	 * the map in 'entry', a logical replication data structure, contains
+	 * 0-based attribute numbers (of the remote relation).
+	 */
+	if (map)
+	{
+		AttrNumber	attno;
+
+		entry->attrmap = make_attrmap(map->maplen);
+		for (attno = 0; attno < entry->attrmap->maplen; attno++)
+		{
+			AttrNumber	root_attno = map->attnums[attno];
+
+			entry->attrmap->attnums[attno] = attrmap->attnums[root_attno - 1];
+		}
+	}
+	else
+		entry->attrmap = attrmap;
+
+	entry->updatable = root->updatable;
+
+	/* state and statelsn are left set to 0. */
+	MemoryContextSwitchTo(oldctx);
+
+	return entry;
+}

src/backend/replication/logical/tablesync.c

@@ -762,7 +762,6 @@ 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/logical/worker.c

@@ -29,11 +29,14 @@
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
 #include "catalog/namespace.h"
+#include "catalog/partition.h"
+#include "catalog/pg_inherits.h"
 #include "catalog/pg_subscription.h"
 #include "catalog/pg_subscription_rel.h"
 #include "commands/tablecmds.h"
 #include "commands/trigger.h"
 #include "executor/executor.h"
+#include "executor/execPartition.h"
 #include "executor/nodeModifyTable.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
@@ -126,6 +129,12 @@ static bool FindReplTupleInLocalRel(EState *estate, Relation localrel,
 									LogicalRepRelation *remoterel,
 									TupleTableSlot *remoteslot,
 									TupleTableSlot **localslot);
+static void apply_handle_tuple_routing(ResultRelInfo *relinfo,
+									   EState *estate,
+									   TupleTableSlot *remoteslot,
+									   LogicalRepTupleData *newtup,
+									   LogicalRepRelMapEntry *relmapentry,
+									   CmdType operation);
 
 /*
  * Should this worker apply changes for given relation.
@@ -636,9 +645,13 @@ apply_handle_insert(StringInfo s)
 	slot_fill_defaults(rel, estate, remoteslot);
 	MemoryContextSwitchTo(oldctx);
 
-	Assert(rel->localrel->rd_rel->relkind == RELKIND_RELATION);
-	apply_handle_insert_internal(estate->es_result_relation_info, estate,
-								 remoteslot);
+	/* For a partitioned table, insert the tuple into a partition. */
+	if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+		apply_handle_tuple_routing(estate->es_result_relation_info, estate,
+								   remoteslot, NULL, rel, CMD_INSERT);
+	else
+		apply_handle_insert_internal(estate->es_result_relation_info, estate,
+									 remoteslot);
 
 	PopActiveSnapshot();
 
@@ -767,9 +780,13 @@ apply_handle_update(StringInfo s)
 						has_oldtup ? oldtup.values : newtup.values);
 	MemoryContextSwitchTo(oldctx);
 
-	Assert(rel->localrel->rd_rel->relkind == RELKIND_RELATION);
-	apply_handle_update_internal(estate->es_result_relation_info, estate,
-								 remoteslot, &newtup, rel);
+	/* For a partitioned table, apply update to correct partition. */
+	if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+		apply_handle_tuple_routing(estate->es_result_relation_info, estate,
+								   remoteslot, &newtup, rel, CMD_UPDATE);
+	else
+		apply_handle_update_internal(estate->es_result_relation_info, estate,
+									 remoteslot, &newtup, rel);
 
 	PopActiveSnapshot();
 
@@ -886,9 +903,13 @@ apply_handle_delete(StringInfo s)
 	slot_store_cstrings(remoteslot, rel, oldtup.values);
 	MemoryContextSwitchTo(oldctx);
 
-	Assert(rel->localrel->rd_rel->relkind == RELKIND_RELATION);
-	apply_handle_delete_internal(estate->es_result_relation_info, estate,
-								 remoteslot, &rel->remoterel);
+	/* For a partitioned table, apply delete to correct partition. */
+	if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+		apply_handle_tuple_routing(estate->es_result_relation_info, estate,
+								   remoteslot, NULL, rel, CMD_DELETE);
+	else
+		apply_handle_delete_internal(estate->es_result_relation_info, estate,
+									 remoteslot, &rel->remoterel);
 
 	PopActiveSnapshot();
 
@@ -975,6 +996,235 @@ FindReplTupleInLocalRel(EState *estate, Relation localrel,
 	return found;
 }
 
+/*
+ * This handles insert, update, delete on a partitioned table.
+ */
+static void
+apply_handle_tuple_routing(ResultRelInfo *relinfo,
+						   EState *estate,
+						   TupleTableSlot *remoteslot,
+						   LogicalRepTupleData *newtup,
+						   LogicalRepRelMapEntry *relmapentry,
+						   CmdType operation)
+{
+	Relation	parentrel = relinfo->ri_RelationDesc;
+	ModifyTableState *mtstate = NULL;
+	PartitionTupleRouting *proute = NULL;
+	ResultRelInfo *partrelinfo;
+	Relation	partrel;
+	TupleTableSlot *remoteslot_part;
+	PartitionRoutingInfo *partinfo;
+	TupleConversionMap *map;
+	MemoryContext oldctx;
+
+	/* ModifyTableState is needed for ExecFindPartition(). */
+	mtstate = makeNode(ModifyTableState);
+	mtstate->ps.plan = NULL;
+	mtstate->ps.state = estate;
+	mtstate->operation = operation;
+	mtstate->resultRelInfo = relinfo;
+	proute = ExecSetupPartitionTupleRouting(estate, mtstate, parentrel);
+
+	/*
+	 * Find the partition to which the "search tuple" belongs.
+	 */
+	Assert(remoteslot != NULL);
+	oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
+	partrelinfo = ExecFindPartition(mtstate, relinfo, proute,
+									remoteslot, estate);
+	Assert(partrelinfo != NULL);
+	partrel = partrelinfo->ri_RelationDesc;
+
+	/*
+	 * To perform any of the operations below, the tuple must match the
+	 * partition's rowtype. Convert if needed or just copy, using a dedicated
+	 * slot to store the tuple in any case.
+	 */
+	partinfo = partrelinfo->ri_PartitionInfo;
+	remoteslot_part = partinfo->pi_PartitionTupleSlot;
+	if (remoteslot_part == NULL)
+		remoteslot_part = table_slot_create(partrel, &estate->es_tupleTable);
+	map = partinfo->pi_RootToPartitionMap;
+	if (map != NULL)
+		remoteslot_part = execute_attr_map_slot(map->attrMap, remoteslot,
+												remoteslot_part);
+	else
+	{
+		remoteslot_part = ExecCopySlot(remoteslot_part, remoteslot);
+		slot_getallattrs(remoteslot_part);
+	}
+	MemoryContextSwitchTo(oldctx);
+
+	estate->es_result_relation_info = partrelinfo;
+	switch (operation)
+	{
+		case CMD_INSERT:
+			apply_handle_insert_internal(partrelinfo, estate,
+										 remoteslot_part);
+			break;
+
+		case CMD_DELETE:
+			apply_handle_delete_internal(partrelinfo, estate,
+										 remoteslot_part,
+										 &relmapentry->remoterel);
+			break;
+
+		case CMD_UPDATE:
+
+			/*
+			 * For UPDATE, depending on whether or not the updated tuple
+			 * satisfies the partition's constraint, perform a simple UPDATE
+			 * of the partition or move the updated tuple into a different
+			 * suitable partition.
+			 */
+			{
+				AttrMap    *attrmap = map ? map->attrMap : NULL;
+				LogicalRepRelMapEntry *part_entry;
+				TupleTableSlot *localslot;
+				ResultRelInfo *partrelinfo_new;
+				bool		found;
+
+				part_entry = logicalrep_partition_open(relmapentry, partrel,
+													   attrmap);
+
+				/* Get the matching local tuple from the partition. */
+				found = FindReplTupleInLocalRel(estate, partrel,
+												&part_entry->remoterel,
+												remoteslot_part, &localslot);
+
+				oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
+				if (found)
+				{
+					/* Apply the update.  */
+					slot_modify_cstrings(remoteslot_part, localslot,
+										 part_entry,
+										 newtup->values, newtup->changed);
+					MemoryContextSwitchTo(oldctx);
+				}
+				else
+				{
+					/*
+					 * The tuple to be updated could not be found.
+					 *
+					 * TODO what to do here, change the log level to LOG
+					 * perhaps?
+					 */
+					elog(DEBUG1,
+						 "logical replication did not find row for update "
+						 "in replication target relation \"%s\"",
+						 RelationGetRelationName(partrel));
+				}
+
+				/*
+				 * Does the updated tuple still satisfy the current
+				 * partition's constraint?
+				 */
+				if (partrelinfo->ri_PartitionCheck == NULL ||
+					ExecPartitionCheck(partrelinfo, remoteslot_part, estate,
+									   false))
+				{
+					/*
+					 * Yes, so simply UPDATE the partition.  We don't call
+					 * apply_handle_update_internal() here, which would
+					 * normally do the following work, to avoid repeating some
+					 * work already done above to find the local tuple in the
+					 * partition.
+					 */
+					EPQState	epqstate;
+
+					EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
+					ExecOpenIndices(partrelinfo, false);
+
+					EvalPlanQualSetSlot(&epqstate, remoteslot_part);
+					ExecSimpleRelationUpdate(estate, &epqstate, localslot,
+											 remoteslot_part);
+					ExecCloseIndices(partrelinfo);
+					EvalPlanQualEnd(&epqstate);
+				}
+				else
+				{
+					/* Move the tuple into the new partition. */
+
+					/*
+					 * New partition will be found using tuple routing, which
+					 * can only occur via the parent table.  We might need to
+					 * convert the tuple to the parent's rowtype.  Note that
+					 * this is the tuple found in the partition, not the
+					 * original search tuple received by this function.
+					 */
+					if (map)
+					{
+						TupleConversionMap *PartitionToRootMap =
+						convert_tuples_by_name(RelationGetDescr(partrel),
+											   RelationGetDescr(parentrel));
+
+						remoteslot =
+							execute_attr_map_slot(PartitionToRootMap->attrMap,
+												  remoteslot_part, remoteslot);
+					}
+					else
+					{
+						remoteslot = ExecCopySlot(remoteslot, remoteslot_part);
+						slot_getallattrs(remoteslot);
+					}
+
+
+					/* Find the new partition. */
+					oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
+					partrelinfo_new = ExecFindPartition(mtstate, relinfo,
+														proute, remoteslot,
+														estate);
+					MemoryContextSwitchTo(oldctx);
+					Assert(partrelinfo_new != partrelinfo);
+
+					/* DELETE old tuple found in the old partition. */
+					estate->es_result_relation_info = partrelinfo;
+					apply_handle_delete_internal(partrelinfo, estate,
+												 localslot,
+												 &relmapentry->remoterel);
+
+					/* INSERT new tuple into the new partition. */
+
+					/*
+					 * Convert the replacement tuple to match the destination
+					 * partition rowtype.
+					 */
+					oldctx = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
+					partrel = partrelinfo_new->ri_RelationDesc;
+					partinfo = partrelinfo_new->ri_PartitionInfo;
+					remoteslot_part = partinfo->pi_PartitionTupleSlot;
+					if (remoteslot_part == NULL)
+						remoteslot_part = table_slot_create(partrel,
+															&estate->es_tupleTable);
+					map = partinfo->pi_RootToPartitionMap;
+					if (map != NULL)
+					{
+						remoteslot_part = execute_attr_map_slot(map->attrMap,
+																remoteslot,
+																remoteslot_part);
+					}
+					else
+					{
+						remoteslot_part = ExecCopySlot(remoteslot_part,
+													   remoteslot);
+						slot_getallattrs(remoteslot);
+					}
+					MemoryContextSwitchTo(oldctx);
+					estate->es_result_relation_info = partrelinfo_new;
+					apply_handle_insert_internal(partrelinfo_new, estate,
+												 remoteslot_part);
+				}
+			}
+			break;
+
+		default:
+			elog(ERROR, "unrecognized CmdType: %d", (int) operation);
+			break;
+	}
+
+	ExecCleanupTupleRouting(mtstate, proute);
+}
+
 /*
  * Handle TRUNCATE message.
  *
@@ -988,6 +1238,7 @@ apply_handle_truncate(StringInfo s)
 	List	   *remote_relids = NIL;
 	List	   *remote_rels = NIL;
 	List	   *rels = NIL;
+	List	   *part_rels = NIL;
 	List	   *relids = NIL;
 	List	   *relids_logged = NIL;
 	ListCell   *lc;
@@ -1017,6 +1268,47 @@ apply_handle_truncate(StringInfo s)
 		relids = lappend_oid(relids, rel->localreloid);
 		if (RelationIsLogicallyLogged(rel->localrel))
 			relids_logged = lappend_oid(relids_logged, rel->localreloid);
+
+		/*
+		 * Truncate partitions if we got a message to truncate a partitioned
+		 * table.
+		 */
+		if (rel->localrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+		{
+			ListCell   *child;
+			List	   *children = find_all_inheritors(rel->localreloid,
+													   RowExclusiveLock,
+													   NULL);
+
+			foreach(child, children)
+			{
+				Oid			childrelid = lfirst_oid(child);
+				Relation	childrel;
+
+				if (list_member_oid(relids, childrelid))
+					continue;
+
+				/* find_all_inheritors already got lock */
+				childrel = table_open(childrelid, NoLock);
+
+				/*
+				 * Ignore temp tables of other backends.  See similar code in
+				 * ExecuteTruncate().
+				 */
+				if (RELATION_IS_OTHER_TEMP(childrel))
+				{
+					table_close(childrel, RowExclusiveLock);
+					continue;
+				}
+
+				rels = lappend(rels, childrel);
+				part_rels = lappend(part_rels, childrel);
+				relids = lappend_oid(relids, childrelid);
+				/* Log this relation only if needed for logical decoding */
+				if (RelationIsLogicallyLogged(childrel))
+					relids_logged = lappend_oid(relids_logged, childrelid);
+			}
+		}
 	}
 
 	/*
@@ -1032,6 +1324,12 @@ apply_handle_truncate(StringInfo s)
 
 		logicalrep_rel_close(rel, NoLock);
 	}
+	foreach(lc, part_rels)
+	{
+		Relation	rel = lfirst(lc);
+
+		table_close(rel, NoLock);
+	}
 
 	CommandCounterIncrement();
 }