Allow to create unlogged IMMVs

Makefile

@@ -14,7 +14,8 @@ EXTENSION = pg_ivm
 DATA = pg_ivm--1.0.sql \
        pg_ivm--1.0--1.1.sql pg_ivm--1.1--1.2.sql pg_ivm--1.2--1.3.sql \
        pg_ivm--1.3--1.4.sql pg_ivm--1.4--1.5.sql pg_ivm--1.5--1.6.sql \
-       pg_ivm--1.6--1.7.sql pg_ivm--1.7--1.8.sql pg_ivm--1.8--1.9.sql
+       pg_ivm--1.6--1.7.sql pg_ivm--1.7--1.8.sql pg_ivm--1.8--1.9.sql \
+       pg_ivm--1.9--1.10.sql
 
 REGRESS = pg_ivm create_immv refresh_immv
 

README.md

@@ -86,15 +86,21 @@ When `pg_ivm` is installed, the following objects are created.
 
 Use `create_immv` function to create IMMV.
 ```
-create_immv(immv_name text, view_definition text) RETURNS bigint
+create_immv(immv_name text, view_definition text [, unlogged bool DEFAULT false]) RETURNS bigint
 ```
 `create_immv` defines a new IMMV of a query. A table of the name `immv_name` is created and a query specified by `view_definition` is executed and used to populate the IMMV. The query is stored in `pg_ivm_immv`, so that it can be refreshed later upon incremental view maintenance. `create_immv` returns the number of rows in the created IMMV.
 
 When an IMMV is created, some triggers are automatically created so that the view's contents are immediately updated when its base tables are modified. In addition, a unique index is created on the IMMV automatically if possible.  If the view definition query has a GROUP BY clause, a unique index is created on the columns of GROUP BY expressions. Also, if the view has DISTINCT clause, a unique index is created on all columns in the target list. Otherwise, if the IMMV contains all primary key attributes of its base tables in the target list, a unique index is created on these attributes.  In other cases, no index is created.
 
 Note that if you use PostgreSQL 17 or later, while `create_immv` is running, the `search_path` is temporarily changed to `pg_catalog, pg_temp`.
 
-#### refresh_imm
+In some cases (e.g. for very large IMMVs containing volatile data), and only if you really know what you are doing, it may be useful to create an IMMV without writing to the [PostgreSQL Write-Ahead Logs](https://www.postgresql.org/docs/current/wal-intro.html) (the underlying table is created with the `UNLOGGED` parameter). Unlogged tables improve write performance, reduce vacuum impact and produce fewer WALs (thus reducing network usage, backup size and restoration time).
+```sql
+SELECT create_immv('myview', 'SELECT * FROM mytab', true);
+```
+**Important:** see the [PostgreSQL documentation](https://www.postgresql.org/docs/current/sql-createtable.html#SQL-CREATETABLE-UNLOGGED) for unlogged tables **DRAWBACKS** (not replicated or included in physical backups, truncated in case of PostgreSQL crash, ...).
+
+#### refresh_immv
 
 Use `refresh_immv` function to refresh IMMV.
 ```
@@ -267,7 +273,7 @@ If some base tables have row level security policy, rows that are not visible to
 
 IVM is effective when we want to keep an IMMV up-to-date and small fraction of a base table is modified infrequently.  Due to the overhead of immediate maintenance, IVM is not effective when a base table is modified frequently.  Also, when a large part of a base table is modified or large data is inserted into a base table, IVM is not effective and the cost of maintenance can be larger than refresh from scratch.
 
-In such situation, we can use `refesh_immv` function with `with_data = false` to disable immediate maintenance before modifying a base table. After a base table modification, call `refresh_immv`with `with_data = true` to refresh the view data and enable immediate maintenance.
+In such situation, we can use `refresh_immv` function with `with_data = false` to disable immediate maintenance before modifying a base table. After a base table modification, call `refresh_immv`with `with_data = true` to refresh the view data and enable immediate maintenance.
 
 ## Authors
 IVM Development Group

createas.c

@@ -234,14 +234,22 @@ create_immv_nodata(List *tlist, IntoClause *into)
  */
 ObjectAddress
 ExecCreateImmv(ParseState *pstate, CreateTableAsStmt *stmt,
-				  ParamListInfo params, QueryEnvironment *queryEnv,
-				  QueryCompletion *qc)
+				  bool unlogged, ParamListInfo params,
+				  QueryEnvironment *queryEnv, QueryCompletion *qc)
 {
 	Query	   *query = castNode(Query, stmt->query);
 	IntoClause *into = stmt->into;
 	bool		do_refresh = false;
 	ObjectAddress address;
 
+	/*
+	 * For volatile data, it can be useful not to write to WALs.
+	 * SEE THE POSTGRESQL DOCUMENTATION FOR DRAWBACKS (not replicated or included in physical backups, truncated in case of a crash, ...):
+	 * https://www.postgresql.org/docs/current/sql-createtable.html#SQL-CREATETABLE-UNLOGGED
+	 */
+	if (unlogged)
+		into->rel->relpersistence = RELPERSISTENCE_UNLOGGED;
+
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;

pg_ivm--1.9--1.10.sql

@@ -0,0 +1,9 @@
+-- functions
+
+CREATE FUNCTION create_immv(text, text, boolean default false)
+RETURNS bigint
+STRICT
+AS 'MODULE_PATHNAME', 'create_immv'
+LANGUAGE C;
+
+DROP FUNCTION create_immv(text, text);

pg_ivm.c

@@ -173,6 +173,7 @@ create_immv(PG_FUNCTION_ARGS)
 {
 	text	*t_relname = PG_GETARG_TEXT_PP(0);
 	text	*t_sql = PG_GETARG_TEXT_PP(1);
+	bool	unlogged = PG_GETARG_BOOL(2);
 	char	*relname = text_to_cstring(t_relname);
 	char	*sql = text_to_cstring(t_sql);
 	List	*parsetree_list;
@@ -228,7 +229,7 @@ create_immv(PG_FUNCTION_ARGS)
 	query = transformStmt(pstate, (Node *)ctas);
 	Assert(query->commandType == CMD_UTILITY && IsA(query->utilityStmt, CreateTableAsStmt));
 
-	ExecCreateImmv(pstate, (CreateTableAsStmt *) query->utilityStmt, NULL, NULL, &qc);
+	ExecCreateImmv(pstate, (CreateTableAsStmt *) query->utilityStmt, unlogged, NULL, NULL, &qc);
 
 	PG_RETURN_INT64(qc.nprocessed);
 }

pg_ivm.control

@@ -1,6 +1,6 @@
 # incremental view maintenance extension_
 comment = 'incremental view maintenance on PostgreSQL'
-default_version = '1.9'
+default_version = '1.10'
 module_pathname = '$libdir/pg_ivm'
 relocatable = false 
 schema = pg_catalog

pg_ivm.h

@@ -35,7 +35,7 @@ extern bool isImmv(Oid immv_oid);
 
 /* createas.c */
 
-extern ObjectAddress ExecCreateImmv(ParseState *pstate, CreateTableAsStmt *stmt,
+extern ObjectAddress ExecCreateImmv(ParseState *pstate, CreateTableAsStmt *stmt, bool unlogged,
 									ParamListInfo params, QueryEnvironment *queryEnv,
 									QueryCompletion *qc);
 extern void CreateIvmTriggersOnBaseTables(Query *qry, Oid matviewOid);

rpm/pg_ivm.spec

@@ -10,7 +10,7 @@
 
 Summary:	PostgreSQL-based distributed RDBMS
 Name:		%{sname}_%{pgmajorversion}
-Version:	1.9
+Version:	1.10
 Release:	1%{dist}
 License:    BSD
 Vendor:     IVM Development Group
@@ -55,6 +55,8 @@ PATH=%{pginstdir}/bin:$PATH %{__make} %{?_smp_mflags} INSTALL_PREFIX=%{buildroot
 %endif
 
 %changelog
+* Mon Aug 26 2024 - Jamal Boukaffal <[email protected]> 1.10-1
+- Update to 1.10
 * Fri Jul 31 2024 - Yugo Nagata <[email protected]> 1.9-1
 - Update to 1.9
 * Fri Mar 1 2024 - Yugo Nagata <[email protected]> 1.8-1