Use unique id as a prefix in CIMV creation

Relname itself is not unique across the database hence for internal CIMV
related tables we use a unique id prefix instead of just relname
so that the same mv in two different schemas don't cause overlap.

src/backend/distributed/cimv/create.c

@@ -17,6 +17,9 @@
 #include "distributed/pg_cimv.h"
 #include "distributed/listutils.h"
 #include "distributed/metadata_cache.h"
+#include "distributed/security_utils.h"
+#include "distributed/sequence_utils.h"
+#include "distributed/coordinator_protocol.h"
 #include "executor/spi.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
@@ -64,6 +67,8 @@ typedef struct
 	CitusTableCacheEntry *citusTable;
 	TargetEntry *partitionColumn;
 	bool supportsDelete;
+	char* prefix;
+	int prefixId;
 } CimvCreate;
 
 static void CreateCimv(CimvCreate *cimvCreate);
@@ -97,6 +102,8 @@ static Oid PartialAggOid(void);
 static void AppendQuotedLiteral(StringInfo buf, const char *val);
 static void AppendStringInfoFunction(StringInfo buf, Oid fnoid);
 static Oid AggregateFunctionOid(const char *functionName, Oid inputType);
+static char* CIMVTriggerFuncName(int prefixId, const char* relname);
+static char* CIMVInternalPrefix(const RangeVar* baseTable, int prefixId);
 
 bool
 ProcessCreateMaterializedViewStmt(const CreateTableAsStmt *stmt, const char *query_string,
@@ -864,28 +871,33 @@ InitializeCimvCreate(const CreateTableAsStmt *stmt, MatViewCreateOptions *create
 	cimvCreate->formCimv->jobid = 0;
 	cimvCreate->formCimv->landingtable = InvalidOid;
 
-	namestrcpy(&cimvCreate->formCimv->triggerfnnamespace, CITUS_INTERNAL_SCHEMA);
-	namestrcpy(&cimvCreate->formCimv->triggerfnname, stmt->into->rel->relname);
-
-	StringInfo mat = makeStringInfo();
-	appendStringInfo(mat, "%s_cimv_%s", stmt->into->rel->relname,
-					 MATERIALIZATION_TABLE_SUFFIX);
-
-	StringInfo rv = makeStringInfo();
-	appendStringInfo(rv, "%s_cimv_%s", stmt->into->rel->relname, REFRESH_VIEW_SUFFIX);
-
-	StringInfo ld = makeStringInfo();
-	appendStringInfo(ld, "%s_cimv_%s", stmt->into->rel->relname, LANDING_TABLE_SUFFIX);
 
 	Query *query = (Query *) stmt->query;
 	RangeTblEntry *baseRte = (RangeTblEntry *) linitial(query->rtable);
 
+	cimvCreate->baseTableName = makeRangeVar(get_namespace_name(get_rel_namespace(
+																baseRte->relid)),
+											get_rel_name(baseRte->relid), -1);
+
 	cimvCreate->stmt = stmt;
 	cimvCreate->createOptions = createOptions;
-	cimvCreate->baseTableName = makeRangeVar(get_namespace_name(get_rel_namespace(
+
-																	baseRte->relid)),
-											 get_rel_name(baseRte->relid), -1);
 	cimvCreate->formCimv->basetable = baseRte->relid;
+
+	cimvCreate->prefixId = UniqueId();
+	cimvCreate->prefix = CIMVInternalPrefix(cimvCreate->baseTableName, cimvCreate->prefixId);
+	namestrcpy(&cimvCreate->formCimv->triggerfnnamespace, CITUS_INTERNAL_SCHEMA);
+	char* funcName = CIMVTriggerFuncName(cimvCreate->prefixId, stmt->into->rel->relname);
+	namestrcpy(&cimvCreate->formCimv->triggerfnname, funcName);
+	StringInfo mat = makeStringInfo();
+	appendStringInfo(mat, "%s_cimv_%s", cimvCreate->prefix, MATERIALIZATION_TABLE_SUFFIX);
+
+	StringInfo rv = makeStringInfo();
+	appendStringInfo(rv, "%s_cimv_%s", cimvCreate->prefix, REFRESH_VIEW_SUFFIX);
+
+	StringInfo ld = makeStringInfo();
+	appendStringInfo(ld, "%s_cimv_%s", cimvCreate->prefix, LANDING_TABLE_SUFFIX);
+
 	cimvCreate->matTableName = makeRangeVar(CITUS_INTERNAL_SCHEMA, mat->data, -1);
 	cimvCreate->userViewName = stmt->into->rel;
 	cimvCreate->refreshViewName = makeRangeVar(CITUS_INTERNAL_SCHEMA, rv->data, -1);
@@ -918,6 +930,24 @@ InitializeCimvCreate(const CreateTableAsStmt *stmt, MatViewCreateOptions *create
 	return cimvCreate;
 }
 
+static char* CIMVTriggerFuncName(int prefixId, const char* relname) {
+	StringInfo funcName = makeStringInfo();
+	appendStringInfo(funcName, "%s_%d",quote_identifier(relname), prefixId);
+	return funcName->data;
+}
+
+static char* CIMVInternalPrefix(const RangeVar* baseTable, int prefixId) {
+
+	if (baseTable->schemaname == NULL || baseTable->relname == NULL) {
+		ereport(ERROR, (errmsg("unexpected state: schema name or relname not found.")));
+	}
+
+	StringInfo prefix = makeStringInfo();
+	appendStringInfo(prefix, "%s_%s_%d",quote_identifier(baseTable->schemaname), 
+		quote_identifier(baseTable->relname), prefixId);
+	return prefix->data;
+}
+
 
 static MatViewCreateOptions *
 GetMatViewCreateOptions(const CreateTableAsStmt *stmt)

src/backend/distributed/sql/citus--9.5-1--10.0-1.sql

@@ -6,5 +6,6 @@ DROP FUNCTION IF EXISTS pg_catalog.citus_total_relation_size(regclass);
 #include "udfs/citus_total_relation_size/10.0-1.sql"
 #include "udfs/citus_tables/10.0-1.sql"
 #include "udfs/citus_finish_pg_upgrade/10.0-1.sql"
+#include "udfs/citus_unique_id/10.0-1.sql"
 
 #include "../../columnar/sql/columnar--9.5-1--10.0-1.sql"

src/backend/distributed/sql/downgrades/citus--10.0-1--9.5-1.sql

@@ -7,6 +7,7 @@
 
 DROP VIEW public.citus_tables;
 DROP FUNCTION pg_catalog.citus_total_relation_size(regclass,boolean);
+DROP SEQUENCE citus_unique_id;
 
 #include "../udfs/citus_total_relation_size/7.0-1.sql"
 #include "../udfs/upgrade_to_reference_table/8.0-1.sql"

src/backend/distributed/sql/udfs/citus_unique_id/10.0-1.sql

@@ -0,0 +1,4 @@
+CREATE SEQUENCE citus.citus_unique_id
+    MINVALUE 1
+    NO CYCLE;
+ALTER SEQUENCE citus.citus_unique_id SET SCHEMA pg_catalog;

src/backend/distributed/sql/udfs/citus_unique_id/latest.sql

@@ -0,0 +1,4 @@
+CREATE SEQUENCE citus.citus_unique_id
+    MINVALUE 1
+    NO CYCLE;
+ALTER SEQUENCE citus.citus_unique_id SET SCHEMA pg_catalog;

src/backend/distributed/utils/sequence_utils.c

@@ -0,0 +1,24 @@
+
+#include "postgres.h"
+
+#include "commands/sequence.h"
+#include "fmgr.h"
+
+#include "distributed/sequence_utils.h"
+#include "distributed/coordinator_protocol.h"
+
+#include "utils/builtins.h"
+
+
+
+int UniqueId(void) {
+	text *sequenceName = cstring_to_text(CITUS_UNIQUE_ID_SEQUENCE_NAME);
+	Oid sequenceId = ResolveRelationId(sequenceName, false);
+	Datum sequenceIdDatum = ObjectIdGetDatum(sequenceId);
+
+	Datum uniqueIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
+
+	int uniqueId = DatumGetInt64(uniqueIdDatum);
+
+	return uniqueId;
+}

src/include/distributed/coordinator_protocol.h

@@ -56,6 +56,7 @@
 
 #define SHARDID_SEQUENCE_NAME "pg_dist_shardid_seq"
 #define PLACEMENTID_SEQUENCE_NAME "pg_dist_placement_placementid_seq"
+#define CITUS_UNIQUE_ID_SEQUENCE_NAME "citus_unique_id"
 
 /* Remote call definitions to help with data staging and deletion */
 #define WORKER_APPLY_SHARD_DDL_COMMAND \

src/include/distributed/sequence_utils.h

@@ -0,0 +1,16 @@
+/*-------------------------------------------------------------------------
+ *
+ * sequence_utils.h
+ *   sequence related utility functions.
+ *
+ * Copyright (c) Citus Data, Inc.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef SEQUENCE_UTILS_H_
+#define SEQUENCE_UTILS_H_
+
+extern int UniqueId(void);
+
+#endif

src/test/regress/sql/cimv.sql

@@ -354,6 +354,29 @@ GROUP BY a, d_hour WITH NO DATA;
 
 SELECT * FROM mv;
 
+-- make sure same mv can be created in different schemas without overlap
+CREATE SCHEMA another_schema;
+SET search_path to another_schema;
+SET citus.shard_count TO 4;
+
+CREATE TABLE events (a int, b int, c double precision, d timestamp, e bigint);
+
+CREATE MATERIALIZED VIEW mv WITH (citus.cimv) AS
+SELECT a,
+       date_trunc('hour', d) AS d_hour,
+       min(b) AS min_b,
+       max(b) AS max_b,
+       avg(b) AS avg_b,
+       min(c) AS min_c,
+       max(c) AS max_c,
+       avg(c) AS avg_c,
+       min(e) AS min_e,
+       max(e) AS max_e,
+       avg(e) AS avg_e
+FROM events
+WHERE b > 10
+GROUP BY a, d_hour;
+
 DROP MATERIALIZED VIEW mv;
 
 SET client_min_messages TO WARNING; -- suppress cascade messages