WIP: Allow partitioned tables in IMMVs

This isn't feature-complete yet, but opening as a place to start a con-
versation around how to fully implement this feature.

At the moment, the prohibition on partitioned tables is removed, and
hooks are added to handle ATTACH PARTITION and DETACH PARTITION.

To do:

  * Add check to prohibit multiple partitioned tables (causes crash)
  * Change ATTACH/DETACH to be incremental (presently does a REFRESH)
  * Figure out issue with multiple tables and correct it

createas.c

@@ -897,10 +897,6 @@ check_ivm_restriction_walker(Node *node, check_ivm_restriction_context *context)
 								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 								 errmsg("TABLESAMPLE clause is not supported on incrementally maintainable materialized view")));
 
-					if (rte->relkind == RELKIND_PARTITIONED_TABLE)
-						ereport(ERROR,
-								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-								 errmsg("partitioned table is not supported on incrementally maintainable materialized view")));
 
 					if (rte->relkind == RELKIND_RELATION && has_superclass(rte->relid))
 						ereport(ERROR,

expected/refresh_immv.out

@@ -116,3 +116,33 @@ ERROR:  relation "mv_not_existing" does not exist
 -- Try to refresh a normal table -- error
 SELECT refresh_immv('t', true);
 ERROR:  "t" is not an IMMV
+-- Create partitioned table
+CREATE TABLE foo (id integer) PARTITION BY RANGE(id);
+CREATE TABLE foo_default PARTITION OF foo DEFAULT;
+INSERT INTO foo VALUES (1), (2), (3);
+SELECT create_immv('foo_mv', 'SELECT COUNT(*) as count FROM foo');
+ create_immv 
+-------------
+           1
+(1 row)
+
+SELECT count FROM foo_mv;
+ count 
+-------
+     3
+(1 row)
+
+ALTER TABLE foo DETACH PARTITION foo_default;
+SELECT count FROM foo_mv;
+ count 
+-------
+     0
+(1 row)
+
+ALTER TABLE foo ATTACH PARTITION foo_default DEFAULT;
+SELECT count FROM foo_mv;
+ count 
+-------
+     3
+(1 row)
+

matview.c

@@ -41,6 +41,7 @@
 #include "rewrite/rewriteManip.h"
 #include "rewrite/rowsecurity.h"
 #include "storage/lmgr.h"
+#include "tcop/deparse_utility.h"
 #include "tcop/tcopprot.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
@@ -220,6 +221,7 @@ static void mv_BuildQueryKey(MV_QueryKey *key, Oid matview_id, int32 query_type)
 static void clean_up_IVM_hash_entry(MV_TriggerHashEntry *entry, bool is_abort);
 
 /* SQL callable functions */
+PG_FUNCTION_INFO_V1(changes_partitions);
 PG_FUNCTION_INFO_V1(IVM_immediate_before);
 PG_FUNCTION_INFO_V1(IVM_immediate_maintenance);
 PG_FUNCTION_INFO_V1(ivm_visible_in_prestate);
@@ -683,12 +685,59 @@ tuplestore_copy(Tuplestorestate *tuplestore, Relation rel)
  */
 
 /*
- * IVM_immediate_before
+ * changes_partitions
  *
- * IVM trigger function invoked before base table is modified. If this is
+ * Accepts a parsed ALTER TABLE command (from pg_event_trigger_ddl_commands),
- * invoked firstly in the same statement, we save the transaction id and the
+ * returning whether that ALTER TABLE command contains subcommands related to
- * command id at that time.
+ * changing partitions (i.e. ATTACH or DETACH PARTITION).
  */
+Datum
+changes_partitions(PG_FUNCTION_ARGS)
+{
+	CollectedCommand *cmd = (CollectedCommand *) PG_GETARG_POINTER(0);
+	ListCell *subcmdCell = NULL;
+
+	CollectedATSubcmd *collAlterSubcmd = NULL;
+	AlterTableCmd *alterCmd = NULL;
+
+	Oid newPartRelid = InvalidOid;
+	Oid oldPartRelid = InvalidOid;
+
+	/* this function is intended for ALTER TABLE only */
+	if (cmd->type != SCT_AlterTable)
+	{
+		elog(ERROR, "command is not ALTER TABLE");
+	}
+
+	/* expect at least one sub-command */
+	subcmdCell = list_head(cmd->d.alterTable.subcmds);
+	if (subcmdCell == NULL)
+	{
+		elog(ERROR, "empty alter table subcommand list");
+	}
+
+	/*
+	 * This saves the OIDs of the affected partitions, for later use
+	 * in an incremental approach.
+	 */
+	collAlterSubcmd = lfirst(subcmdCell);
+	alterCmd = castNode(AlterTableCmd, collAlterSubcmd->parsetree);
+	if (alterCmd->subtype == AT_AttachPartition)
+	{
+		newPartRelid = collAlterSubcmd->address.objectId;
+	}
+	else if (alterCmd->subtype == AT_DetachPartition)
+	{
+		oldPartRelid = collAlterSubcmd->address.objectId;
+	}
+	else
+	{
+		return BoolGetDatum(false);
+	}
+
+	return BoolGetDatum(true);
+}
+
 Datum
 IVM_immediate_before(PG_FUNCTION_ARGS)
 {

pg_ivm--1.0.sql

@@ -17,8 +17,22 @@ SELECT pg_catalog.pg_extension_config_dump('pg_catalog.pg_ivm_immv', '');
 
 -- functions
 
+CREATE FUNCTION changes_partitions(pg_ddl_command)
+RETURNS boolean
+IMMUTABLE
+STRICT
+AS 'MODULE_PATHNAME', 'changes_partitions'
+LANGUAGE C;
+
+-- CREATE FUNCTION get_command_type(text, text, pg_ddl_command, text)
+-- RETURNS void
+-- IMMUTABLE
+-- STRICT
+-- AS 'MODULE_PATHNAME', 'get_command_type'
+-- LANGUAGE C;
+
 CREATE FUNCTION create_immv(text, text)
-RETURNS bigint 
+RETURNS bigint
 STRICT
 AS 'MODULE_PATHNAME', 'create_immv'
 LANGUAGE C;
@@ -26,17 +40,17 @@ LANGUAGE C;
 -- trigger functions
 
 CREATE FUNCTION "IVM_immediate_before"()
-RETURNS trigger 
+RETURNS trigger
 AS 'MODULE_PATHNAME', 'IVM_immediate_before'
 LANGUAGE C;
 
 CREATE FUNCTION "IVM_immediate_maintenance"()
-RETURNS trigger 
+RETURNS trigger
 AS 'MODULE_PATHNAME', 'IVM_immediate_maintenance'
 LANGUAGE C;
 
 CREATE FUNCTION "IVM_prevent_immv_change"()
-RETURNS trigger 
+RETURNS trigger
 AS 'MODULE_PATHNAME', 'IVM_prevent_immv_change'
 LANGUAGE C;
 
@@ -64,3 +78,33 @@ $$ LANGUAGE plpgsql;
 CREATE EVENT TRIGGER pg_ivm_sql_drop_trigger
 ON sql_drop
 EXECUTE PROCEDURE pg_catalog.pg_ivm_sql_drop_trigger_func();
+
+-- Process ALTER TABLE, specifically ATTACH/DETACH PARTITION
+-- TODO: Get incremental update working
+CREATE OR REPLACE FUNCTION ivm_immediate_event()
+ RETURNS event_trigger
+ LANGUAGE plpgsql
+AS $function$
+DECLARE
+  r record;
+BEGIN
+  FOR r IN SELECT * FROM pg_event_trigger_ddl_commands()
+  LOOP
+    IF changes_partitions(r.command) THEN
+      PERFORM refresh_immv(
+        convert_from(
+          substring(tgargs FOR (position('\x00'::bytea in tgargs)-1)),
+          'SQL_ASCII'
+        )::oid::regclass::text,
+        true)
+      FROM pg_trigger
+      WHERE tgfoid='"IVM_immediate_maintenance"'::regproc AND tgtype=4;
+    END IF;
+  END LOOP;
+END;
+$function$;
+
+-- Run on any ALTER TABLE
+CREATE EVENT TRIGGER IVM_trigger_event
+ON ddl_command_end WHEN TAG IN ('ALTER TABLE')
+EXECUTE PROCEDURE ivm_immediate_event();

pg_ivm.h

@@ -52,6 +52,7 @@ extern ObjectAddress RefreshImmvByOid(Oid matviewOid, bool skipData,
 									  const char *queryString, QueryCompletion *qc);
 extern bool ImmvIncrementalMaintenanceIsEnabled(void);
 extern Query *get_immv_query(Relation matviewRel);
+extern Datum changes_partitions(PG_FUNCTION_ARGS);
 extern Datum IVM_immediate_before(PG_FUNCTION_ARGS);
 extern Datum IVM_immediate_maintenance(PG_FUNCTION_ARGS);
 extern Query* rewrite_query_for_exists_subquery(Query *query);

sql/refresh_immv.sql

@@ -37,3 +37,18 @@ SELECT refresh_immv('mv_not_existing', true);
 
 -- Try to refresh a normal table -- error
 SELECT refresh_immv('t', true);
+
+-- Create partitioned table
+CREATE TABLE foo (id integer) PARTITION BY RANGE(id);
+CREATE TABLE foo_default PARTITION OF foo DEFAULT;
+
+INSERT INTO foo VALUES (1), (2), (3);
+
+SELECT create_immv('foo_mv', 'SELECT COUNT(*) as count FROM foo');
+SELECT count FROM foo_mv;
+
+ALTER TABLE foo DETACH PARTITION foo_default;
+SELECT count FROM foo_mv;
+
+ALTER TABLE foo ATTACH PARTITION foo_default DEFAULT;
+SELECT count FROM foo_mv;