Prohibit unreferenced CTE
When a table in a unreferenced CTE is TRUNCATEd, the contents of the IMMV is not affected so it must not be truncated. For confirming it at the maintenance time, we have to check if the modified table used in a CTE is actually referenced. Although it would possible, we just disallow to create such IMMVs for now since such unreferenced CTE is useless unless it doesn't contain modifying commands, that is already prohibited. Some error messages are fixed to use "WITH query" instead of "CTE" as same as in the PostgreSQL core code. Also, add tests for nested CTE and multiply-referenced CTE, and a test for nested-subquery in passing.
This commit is contained in:
Yugo Nagata
parent
61eca8c30c
commit
8b564de029
4 changed files with 204 additions and 26 deletions
12
README.md
12
README.md
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@ -188,7 +188,7 @@ Time: 3224.741 ms (00:03.225)
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## Supported View Definitions and Restriction
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Currently, IMMV's view definition can contain inner joins, DISTINCT clause, some built-in aggregate functions, and simple sub-queries in `FROM` clause. Inner joins including self-join are supported, but outer joins are not supported. Supported aggregate functions are count, sum, avg, min and max. Other aggregates, sub-queries which contain an aggregate or `DISTINCT` clause, sub-queries in other than `FROM` clause, CTEs, window functions, `HAVING`, `ORDER BY`, `LIMIT`/`OFFSET`, `UNION`/`INTERSECT`/`EXCEPT`, `DISTINCT ON`, `TABLESAMPLE`, `VALUES`, and `FOR UPDATE`/`SHARE` can not be used in view definition.
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Currently, IMMV's view definition can contain inner joins, DISTINCT clause, some built-in aggregate functions, simple sub-queries in `FROM` clause, and simple CTE (`WITH` query). Inner joins including self-join are supported, but outer joins are not supported. Supported aggregate functions are count, sum, avg, min and max. Other aggregates, sub-queries which contain an aggregate or `DISTINCT` clause, sub-queries in other than `FROM` clause, window functions, `HAVING`, `ORDER BY`, `LIMIT`/`OFFSET`, `UNION`/`INTERSECT`/`EXCEPT`, `DISTINCT ON`, `TABLESAMPLE`, `VALUES`, and `FOR UPDATE`/`SHARE` can not be used in view definition.
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The base tables must be simple tables. Views, materialized views, inheritance parent tables, partitioned tables, partitions, and foreign tables can not be used.
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@ -224,6 +224,16 @@ Subqueries can be used only in `FROM` clause. Subqueries in target list or `WHER
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Subqueries containing an aggregate function or `DISTINCT` are not supported.
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### CTE
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Simple CTEs (`WITH` queries) are supported.
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#### Restrictions on Subqueries
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`WITH` queries containing an aggregate function or `DISTINCT` are not supported.
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Recursive queries (`WITH RECURSIVE`) are not allowed. Unreferenced CTEs are not allowed either, that is, a CTE must be referenced at least once in the view definition query.
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### DISTINCT
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`DISTINCT` is allowed in IMMV's definition queries. Suppose an IMMV defined with DISTINCT on a base table containing duplicate tuples. When tuples are deleted from the base table, a tuple in the view is deleted if and only if the multiplicity of the tuple becomes zero. Moreover, when tuples are inserted into the base table, a tuple is inserted into the view only if the same tuple doesn't already exist in it.
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18
createas.c
18
createas.c
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@ -749,7 +749,7 @@ check_ivm_restriction_walker(Node *node, check_ivm_restriction_context *context)
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if (qry->hasRecursive)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("recursive CTE is not supported on incrementally maintainable materialized view")));
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errmsg("recursive query is not supported on incrementally maintainable materialized view")));
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/* system column restrictions */
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vars = pull_vars_of_level((Node *) qry, 0);
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@ -843,7 +843,21 @@ check_ivm_restriction_walker(Node *node, check_ivm_restriction_context *context)
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if (isIvmName(cte->ctename))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("CTE name %s is not supported on incrementally maintainable materialized view", cte->ctename)));
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errmsg("WITH query name %s is not supported on incrementally maintainable materialized view", cte->ctename)));
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/*
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* When a table in a unreferenced CTE is TRUNCATEd, the contents of the
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* IMMV is not affected so it must not be truncated. For confirming it
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* at the maintenance time, we have to check if the modified table used
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* in a CTE is actually referenced. Although it would be possible, we
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* just disallow to create such IMMVs for now since such unreferenced
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* CTE is useless unless it doesn't contain modifying commands, that is
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* already prohibited.
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*/
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if (cte->cterefcount == 0)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("Ureferenced WITH query is not supported on incrementally maintainable materialized view")));
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context->sublevels_up++;
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check_ivm_restriction_walker(cte->ctequery, (void *) context);
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@ -739,6 +739,39 @@ SELECT * FROM mv_ivm_join_subquery ORDER BY i,j,k;
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3 | 30 | 133
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(8 rows)
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ROLLBACK;
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BEGIN;
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-- nested subquery
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SELECT create_immv('mv_ivm_join_subquery', 'SELECT i, j, k FROM ( SELECT i, a.j, b.k FROM mv_base_b b INNER JOIN (SELECT * FROM mv_base_a) a USING(i)) tmp');
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NOTICE: could not create an index on immv "mv_ivm_join_subquery" automatically
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DETAIL: This target list does not have all the primary key columns, or this view does not contain GROUP BY or DISTINCT clause.
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HINT: Create an index on the immv for efficient incremental maintenance.
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create_immv
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-------------
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4
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(1 row)
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WITH
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ai AS (INSERT INTO mv_base_a VALUES (1,11),(2,22) RETURNING 0),
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bi AS (INSERT INTO mv_base_b VALUES (1,111),(3,133) RETURNING 0),
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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--
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(1 row)
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SELECT * FROM mv_ivm_join_subquery ORDER BY i,j,k;
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i | j | k
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---+----+-----
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1 | 10 | 101
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1 | 10 | 111
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1 | 11 | 101
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1 | 11 | 111
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2 | 20 | 102
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2 | 22 | 102
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3 | 30 | 103
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3 | 30 | 133
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(8 rows)
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ROLLBACK;
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-- support simple CTE
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BEGIN;
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@ -898,12 +931,102 @@ SELECT * FROM mv_cte ORDER BY i,j,k;
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3 | 30 | 133
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(8 rows)
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END; -- don't remove for get_immv_def test
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ROLLBACK;
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-- nested CTE
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BEGIN;
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SELECT create_immv('mv_ivm_nested_cte', 'WITH v AS ( WITH a AS (SELECT * FROM mv_base_a) SELECT i, a.j, b.k FROM mv_base_b b INNER JOIN a USING(i)) SELECT * FROM v');
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NOTICE: could not create an index on immv "mv_ivm_nested_cte" automatically
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DETAIL: This target list does not have all the primary key columns, or this view does not contain GROUP BY or DISTINCT clause.
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HINT: Create an index on the immv for efficient incremental maintenance.
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create_immv
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-------------
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4
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(1 row)
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WITH
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ai AS (INSERT INTO mv_base_a VALUES (1,11),(2,22) RETURNING 0),
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bi AS (INSERT INTO mv_base_b VALUES (1,111),(3,133) RETURNING 0),
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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--
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(1 row)
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SELECT * FROM mv_ivm_nested_cte ORDER BY i,j,k;
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i | j | k
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---+----+-----
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1 | 10 | 101
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1 | 10 | 111
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1 | 11 | 101
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1 | 11 | 111
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2 | 20 | 102
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2 | 22 | 102
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3 | 30 | 103
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3 | 30 | 133
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(8 rows)
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ROLLBACK;
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-- Multiply-referenced CTE
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BEGIN;
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CREATE TABLE base_t (i int, v int);
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INSERT INTO base_t VALUES (1, 10), (2, 20), (3, 30);
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SELECT create_immv('mv_cte_multi(v1, v2)',
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'WITH t AS (SELECT * FROM base_t) SELECT t1.v, t2.v FROM t AS t1 JOIN t AS t2 ON t1.i = t2.i');
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NOTICE: could not create an index on immv "mv_cte_multi" automatically
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DETAIL: This target list does not have all the primary key columns, or this view does not contain GROUP BY or DISTINCT clause.
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HINT: Create an index on the immv for efficient incremental maintenance.
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create_immv
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-------------
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3
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(1 row)
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SELECT * FROM mv_cte_multi ORDER BY v1;
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v1 | v2
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----+----
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10 | 10
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20 | 20
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30 | 30
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(3 rows)
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INSERT INTO base_t VALUES (4,40);
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DELETE FROM base_t WHERE i = 1;
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UPDATE base_t SET v = v*10 WHERE i=2;
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SELECT * FROM mv_cte_multi ORDER BY v1;
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v1 | v2
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-----+-----
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30 | 30
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40 | 40
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200 | 200
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(3 rows)
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WITH
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ins_t1 AS (INSERT INTO base_t VALUES (5,50) RETURNING 1),
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ins_t2 AS (INSERT INTO base_t VALUES (6,60) RETURNING 1),
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upd_t AS (UPDATE base_t SET v = v + 100 RETURNING 1),
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dlt_t AS (DELETE FROM base_t WHERE i IN (4,5) RETURNING 1)
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SELECT NULL;
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?column?
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----------
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(1 row)
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SELECT * FROM mv_cte_multi ORDER BY v1;
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v1 | v2
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-----+-----
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50 | 50
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60 | 60
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130 | 130
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300 | 300
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(4 rows)
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ROLLBACK;
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--- disallow not-simple CTE
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT i, COUNT(*) FROM mv_base_b GROUP BY i) SELECT a.i,a.j FROM mv_base_a a, b WHERE a.i = b.i');
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ERROR: aggregate functions in nested query are not supported on incrementally maintainable materialized view
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT DISTINCT i FROM mv_base_b) SELECT a.i,a.j FROM mv_base_a a, b WHERE a.i = b.i');
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ERROR: DISTINCT clause in nested query are not supported on incrementally maintainable materialized view
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-- unreferenced CTE
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT * FROM mv_base_b) SELECT * FROM mv_base_a a');
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ERROR: Ureferenced WITH query is not supported on incrementally maintainable materialized view
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-- views including NULL
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BEGIN;
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CREATE TABLE base_t (i int, v int);
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@ -1315,25 +1438,14 @@ TRUNCATE mv_ivm_1;
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ERROR: cannot change materialized view "mv_ivm_1"
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-- get_immv_def function
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SELECT immvrelid, get_immv_def(immvrelid) FROM pg_ivm_immv ORDER BY 1;
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immvrelid | get_immv_def
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-----------+------------------------------------------
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mv_ivm_1 | SELECT a.i, +
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| a.j, +
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| b.k +
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| FROM (mv_base_a a +
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immvrelid | get_immv_def
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-----------+----------------------------------
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mv_ivm_1 | SELECT a.i, +
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| a.j, +
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| b.k +
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| FROM (mv_base_a a +
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| JOIN mv_base_b b USING (i))
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mv_cte | WITH x AS ( +
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| SELECT b.i, +
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| a.j, +
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| b.k +
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| FROM (mv_base_b b +
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| JOIN mv_base_a a USING (i))+
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| ) +
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| SELECT i, +
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| j, +
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| k +
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| FROM x
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(2 rows)
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(1 row)
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-- mv_base_b is not immv
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SELECT 'mv_base_b'::regclass, get_immv_def('mv_base_b');
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@ -1343,9 +1455,8 @@ SELECT 'mv_base_b'::regclass, get_immv_def('mv_base_b');
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(1 row)
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DROP TABLE mv_base_b CASCADE;
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NOTICE: drop cascades to 4 other objects
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NOTICE: drop cascades to 3 other objects
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DETAIL: drop cascades to table mv_ivm_1
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drop cascades to table mv_cte
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drop cascades to view b_view
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drop cascades to materialized view b_mview
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DROP TABLE mv_base_a CASCADE;
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@ -233,7 +233,6 @@ SELECT create_immv('mv_ivm_subquery', 'SELECT a.i,a.j FROM mv_base_a a,( SELECT
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INSERT INTO mv_base_a VALUES(2,20);
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INSERT INTO mv_base_b VALUES(3,300);
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SELECT * FROM mv_ivm_subquery ORDER BY i,j;
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ROLLBACK;
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-- disallow non-simple subqueries
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@ -254,7 +253,17 @@ WITH
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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SELECT * FROM mv_ivm_join_subquery ORDER BY i,j,k;
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ROLLBACK;
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BEGIN;
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-- nested subquery
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SELECT create_immv('mv_ivm_join_subquery', 'SELECT i, j, k FROM ( SELECT i, a.j, b.k FROM mv_base_b b INNER JOIN (SELECT * FROM mv_base_a) a USING(i)) tmp');
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WITH
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ai AS (INSERT INTO mv_base_a VALUES (1,11),(2,22) RETURNING 0),
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bi AS (INSERT INTO mv_base_b VALUES (1,111),(3,133) RETURNING 0),
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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SELECT * FROM mv_ivm_join_subquery ORDER BY i,j,k;
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ROLLBACK;
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-- support simple CTE
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@ -307,12 +316,46 @@ WITH
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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SELECT * FROM mv_cte ORDER BY i,j,k;
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END; -- don't remove for get_immv_def test
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ROLLBACK;
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-- nested CTE
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BEGIN;
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SELECT create_immv('mv_ivm_nested_cte', 'WITH v AS ( WITH a AS (SELECT * FROM mv_base_a) SELECT i, a.j, b.k FROM mv_base_b b INNER JOIN a USING(i)) SELECT * FROM v');
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WITH
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ai AS (INSERT INTO mv_base_a VALUES (1,11),(2,22) RETURNING 0),
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bi AS (INSERT INTO mv_base_b VALUES (1,111),(3,133) RETURNING 0),
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bd AS (DELETE FROM mv_base_b WHERE i = 4 RETURNING 0)
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SELECT;
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SELECT * FROM mv_ivm_nested_cte ORDER BY i,j,k;
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ROLLBACK;
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-- Multiply-referenced CTE
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BEGIN;
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CREATE TABLE base_t (i int, v int);
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INSERT INTO base_t VALUES (1, 10), (2, 20), (3, 30);
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SELECT create_immv('mv_cte_multi(v1, v2)',
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'WITH t AS (SELECT * FROM base_t) SELECT t1.v, t2.v FROM t AS t1 JOIN t AS t2 ON t1.i = t2.i');
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SELECT * FROM mv_cte_multi ORDER BY v1;
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INSERT INTO base_t VALUES (4,40);
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DELETE FROM base_t WHERE i = 1;
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UPDATE base_t SET v = v*10 WHERE i=2;
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SELECT * FROM mv_cte_multi ORDER BY v1;
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WITH
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ins_t1 AS (INSERT INTO base_t VALUES (5,50) RETURNING 1),
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ins_t2 AS (INSERT INTO base_t VALUES (6,60) RETURNING 1),
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upd_t AS (UPDATE base_t SET v = v + 100 RETURNING 1),
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dlt_t AS (DELETE FROM base_t WHERE i IN (4,5) RETURNING 1)
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SELECT NULL;
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SELECT * FROM mv_cte_multi ORDER BY v1;
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ROLLBACK;
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--- disallow not-simple CTE
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT i, COUNT(*) FROM mv_base_b GROUP BY i) SELECT a.i,a.j FROM mv_base_a a, b WHERE a.i = b.i');
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT DISTINCT i FROM mv_base_b) SELECT a.i,a.j FROM mv_base_a a, b WHERE a.i = b.i');
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-- unreferenced CTE
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SELECT create_immv('mv_cte_fail', 'WITH b AS (SELECT * FROM mv_base_b) SELECT * FROM mv_base_a a');
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-- views including NULL
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BEGIN;
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CREATE TABLE base_t (i int, v int);
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Reference in a new issue