Event trigger

Makefile

@@ -9,7 +9,8 @@ OBJS = \
 	matview.o \
 	pg_ivm.o \
 	ruleutils.o \
-	subselect.o
+	subselect.o \
+	event_trigger.o
 PGFILEDESC = "pg_ivm - incremental view maintenance on PostgreSQL"
 
 EXTENSION = pg_ivm

event_trigger.c

@@ -0,0 +1,237 @@
+#include "postgres.h"
+#include "pg_ivm.h"
+
+#include "access/table.h"
+#include "catalog/indexing.h"
+#include "commands/event_trigger.h"
+#include "utils/builtins.h"
+#include "utils/guc.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#define IMMV_INIT_QUERYHASHSIZE 16
+
+typedef struct HashEntry
+{
+	Oid			immv_relid;
+	char	   *query;
+}			HashEntry;
+
+/* Stores the Query nodes of each IMMV view query as they were pre-DDL. */
+static HTAB *immv_query_cache;
+
+/* Active snapshot at the time of the pre-DDL trigger. */
+static Snapshot active_snapshot;
+
+static char *retrieve_query(Oid immv_relid);
+static void hash_query(Oid immv_relid, char *query);
+static void initialize_query_cache(void);
+static void restore_query_strings_internal(void);
+static void save_query_strings_internal(void);
+
+PG_FUNCTION_INFO_V1(save_query_strings);
+PG_FUNCTION_INFO_V1(restore_query_strings);
+
+Datum
+save_query_strings(PG_FUNCTION_ARGS)
+{
+	EventTriggerData *trigdata;
+
+	if (!CALLED_AS_EVENT_TRIGGER(fcinfo))
+		ereport(ERROR, errmsg("not fired by event trigger manager"));
+
+	trigdata = (EventTriggerData *) fcinfo->context;
+
+	if (!IsA(trigdata->parsetree, RenameStmt))
+		PG_RETURN_NULL();
+
+	initialize_query_cache();
+	active_snapshot = GetActiveSnapshot();
+	save_query_strings_internal();
+
+	PG_RETURN_NULL();
+}
+
+Datum
+restore_query_strings(PG_FUNCTION_ARGS)
+{
+	EventTriggerData *trigdata;
+
+	if (!CALLED_AS_EVENT_TRIGGER(fcinfo))
+		ereport(ERROR, errmsg("not fired by event trigger manager"));
+
+	trigdata = (EventTriggerData *) fcinfo->context;
+
+	if (!IsA(trigdata->parsetree, RenameStmt))
+		PG_RETURN_NULL();
+
+	restore_query_strings_internal();
+
+	PG_RETURN_NULL();
+}
+
+static void
+initialize_query_cache(void)
+{
+	HASHCTL		ctl;
+
+	memset(&ctl, 0, sizeof(ctl));
+	ctl.keysize = sizeof(Oid);
+	ctl.entrysize = sizeof(HashEntry);
+	immv_query_cache = hash_create("IMMV query cache", IMMV_INIT_QUERYHASHSIZE,
+								   &ctl, HASH_ELEM | HASH_BLOBS);
+}
+
+static void
+hash_query(Oid immv_relid, char *query)
+{
+	HashEntry  *entry;
+	MemoryContext old_cxt;
+	bool		found;
+
+	entry = (HashEntry *) hash_search(immv_query_cache,
+									  &immv_relid,
+									  HASH_ENTER,
+									  &found);
+	Assert(!found);
+
+	old_cxt = MemoryContextSwitchTo(TopTransactionContext);
+	entry->query = pstrdup(query);
+	MemoryContextSwitchTo(old_cxt);
+}
+
+static char *
+retrieve_query(Oid immv_relid)
+{
+	HashEntry  *entry;
+	MemoryContext old_cxt;
+	bool		found;
+	char	   *query;
+
+	entry = (HashEntry *) hash_search(immv_query_cache,
+									  &immv_relid,
+									  HASH_FIND,
+									  &found);
+	Assert(found);
+
+	old_cxt = MemoryContextSwitchTo(TopTransactionContext);
+	query = pstrdup(entry->query);
+	pfree(entry->query);
+	MemoryContextSwitchTo(old_cxt);
+
+	return query;
+}
+
+static void
+save_query_strings_internal(void)
+{
+	HeapTuple	tup;
+	Relation	pg_ivm_immv_rel;
+	SysScanDesc scan;
+	TupleDesc	tupdesc;
+
+	pg_ivm_immv_rel = table_open(PgIvmImmvRelationId(), RowExclusiveLock);
+	scan = systable_beginscan(pg_ivm_immv_rel, PgIvmImmvPrimaryKeyIndexId(),
+							  true, active_snapshot, 0, NULL);
+	tupdesc = RelationGetDescr(pg_ivm_immv_rel);
+
+	while ((tup = systable_getnext(scan)) != NULL)
+	{
+		Oid			matview_oid;
+		ParseState *parse_state;
+		Query	   *query;
+		bool		isnull;
+		char	   *matview_relname;
+		char	   *query_string;
+
+		query_string = TextDatumGetCString(heap_getattr(tup,
+														Anum_pg_ivm_immv_querystring,
+														tupdesc, &isnull));
+		Assert(!isnull);
+
+		matview_oid = DatumGetObjectId(heap_getattr(tup, Anum_pg_ivm_immv_immvrelid,
+													tupdesc, &isnull));
+		Assert(!isnull);
+
+		matview_relname = psprintf("%s.%s",
+								   get_namespace_name(get_rel_namespace(matview_oid)),
+								   get_rel_name(matview_oid));
+
+		/* Parse the existing IMMV query pre-DDL.  Add it to the list. */
+		parse_immv_query(matview_relname, query_string, &query, &parse_state);
+
+		/* Store entry for this IMMV. */
+		hash_query(matview_oid, nodeToString(query));
+	}
+
+	systable_endscan(scan);
+	table_close(pg_ivm_immv_rel, NoLock);
+}
+
+static void
+restore_query_strings_internal(void)
+{
+	HeapTuple	tup;
+	Relation	pg_ivm_immv_rel;
+	SysScanDesc scan;
+	TupleDesc	tupdesc;
+	int			save_nestlevel;
+
+	pg_ivm_immv_rel = table_open(PgIvmImmvRelationId(), RowExclusiveLock);
+	scan = systable_beginscan(pg_ivm_immv_rel, PgIvmImmvPrimaryKeyIndexId(),
+							  true, active_snapshot, 0, NULL);
+	tupdesc = RelationGetDescr(pg_ivm_immv_rel);
+
+	/*
+	 * Restrict search_path so that pg_ivm_get_viewdef_internal returns a
+	 * fully-qualified query.
+	 */
+	save_nestlevel = NewGUCNestLevel();
+	RestrictSearchPath();
+
+	while ((tup = systable_getnext(scan)) != NULL)
+	{
+		Datum		values[Natts_pg_ivm_immv];
+		HeapTuple	newtup;
+		Oid			matview_oid;
+		Query	   *query;
+		Relation	matview_rel;
+		bool		isnull;
+		bool		nulls[Natts_pg_ivm_immv];
+		bool		replaces[Natts_pg_ivm_immv];
+		char	   *new_query_string;
+		char	   *serialized_query;
+
+		matview_oid = DatumGetObjectId(heap_getattr(tup, Anum_pg_ivm_immv_immvrelid,
+													tupdesc, &isnull));
+		Assert(!isnull);
+
+		serialized_query = retrieve_query(matview_oid);
+		query = stringToNode(serialized_query);
+		query = (Query *) ((CreateTableAsStmt *) query->utilityStmt)->into->viewQuery;
+
+		matview_rel = table_open(matview_oid, AccessShareLock);
+		new_query_string = pg_ivm_get_viewdef_internal(query, matview_rel, true);
+		table_close(matview_rel, NoLock);
+
+		memset(values, 0, sizeof(values));
+		values[Anum_pg_ivm_immv_querystring - 1] = CStringGetTextDatum(new_query_string);
+		memset(nulls, false, sizeof(nulls));
+		memset(replaces, false, sizeof(nulls));
+		replaces[Anum_pg_ivm_immv_querystring - 1] = true;
+
+		newtup = heap_modify_tuple(tup, tupdesc, values, nulls, replaces);
+
+		CatalogTupleUpdate(pg_ivm_immv_rel, &newtup->t_self, newtup);
+		heap_freetuple(newtup);
+	}
+
+	systable_endscan(scan);
+	table_close(pg_ivm_immv_rel, NoLock);
+	hash_destroy(immv_query_cache);
+
+	/* Roll back the search_path change. */
+	AtEOXact_GUC(false, save_nestlevel);
+}

pg_ivm--1.10--1.11.sql

@@ -19,34 +19,16 @@ BEGIN
 END
 $$;
 
-CREATE FUNCTION pgivm.refresh_query_strings()
+CREATE FUNCTION pgivm.save_query_strings() RETURNS event_trigger
-RETURNS event_trigger LANGUAGE plpgsql SECURITY DEFINER AS
+AS 'MODULE_PATHNAME', 'save_query_strings' LANGUAGE C;
-$$
-DECLARE
-	old_search_path text;
-BEGIN
-	-- Only need to refresh query strings if an object is renamed.
-	-- As a rough heuristic, check if this is an ALTER command.
-	IF tg_tag LIKE 'ALTER %' THEN
-		-- Empty search path so that get_immv_def returns a fully-qualified query.
-		SELECT setting INTO old_search_path FROM pg_catalog.pg_settings
-			WHERE name = 'search_path';
-		SET search_path = '';
 
-		UPDATE pgivm.pg_ivm_immv SET querystring = pgivm.get_immv_def(immvrelid);
+CREATE FUNCTION pgivm.restore_query_strings() RETURNS event_trigger
+AS 'MODULE_PATHNAME', 'restore_query_strings' LANGUAGE C;
 
-		-- Reset search path to the original value.
+CREATE EVENT TRIGGER save_query_strings
-		IF old_search_path != '' AND old_search_path != '""' THEN
+ON ddl_command_start
-			EXECUTE format('SET search_path = %s', old_search_path);
+EXECUTE FUNCTION pgivm.save_query_strings();
-		END IF;
-	END IF;
-EXCEPTION
-	WHEN internal_error THEN
-		RAISE WARNING 'pg_ivm could not refresh the pg_ivm_immv query strings.'
-			USING HINT = 'Please recreate your IMMVs using pgivm.recreate_all_immvs().';
-END
-$$;
 
-CREATE EVENT TRIGGER refresh_query_strings
+CREATE EVENT TRIGGER restore_query_strings
 ON ddl_command_end
-EXECUTE FUNCTION pgivm.refresh_query_strings();
+EXECUTE FUNCTION pgivm.restore_query_strings();

pg_ivm.h

@@ -72,6 +72,11 @@ extern char *pg_ivm_get_viewdef_internal(Query *query, Relation immvrel, bool pr
 /* subselect.c */
 extern void inline_cte(PlannerInfo *root, CommonTableExpr *cte);
 
+/* event_trigger.c */
+
+extern Datum save_query_string(PG_FUNCTION_ARGS);
+extern Datum restore_query_string(PG_FUNCTION_ARGS);
+
 #if defined(PG_VERSION_NUM) && (PG_VERSION_NUM < 170000)
 extern void RestrictSearchPath(void);
 #endif