MDEV-40672: Pluggable Aggregate Function

bugfix-swarm/review_scratch/function_plugin_filter.result

@@ -0,0 +1,56 @@
+#
+# MDEV-41352 SIGSEGV in Item_field::used_tables on a plugin aggregate
+#            with FILTER
+#
+CREATE TABLE t (c INT);
+SELECT test_plugin_count(1) FILTER (WHERE c) FROM t;
+test_plugin_count(1) FILTER (WHERE c)
+0
+DROP TABLE t;
+CREATE TABLE t (id INT PRIMARY KEY, g INT, v INT);
+INSERT INTO t VALUES (1,1,10),(2,1,20),(3,2,30),(4,2,NULL),(5,3,50);
+SELECT test_plugin_count(v) FILTER (WHERE v > 15) FROM t;
+test_plugin_count(v) FILTER (WHERE v > 15)
+3
+SELECT count(v) FILTER (WHERE v > 15) AS c,
+test_plugin_count(v) FILTER (WHERE v > 15) AS pc,
+test_plugin_first(v) FILTER (WHERE v > 15) AS pf
+FROM t;
+c	pc	pf
+3	3	20
+SELECT g, count(v) FILTER (WHERE id > 1) AS c,
+test_plugin_count(v) FILTER (WHERE id > 1) AS pc,
+test_plugin_first(v) FILTER (WHERE id > 1) AS pf
+FROM t GROUP BY g ORDER BY g;
+g	c	pc	pf
+1	1	1	20
+2	1	1	30
+3	1	1	50
+SELECT count(DISTINCT g) FILTER (WHERE v > 15) AS c,
+test_plugin_count(DISTINCT g) FILTER (WHERE v > 15) AS pc
+FROM t;
+c	pc
+3	3
+SELECT id, count(v) FILTER (WHERE v > 15) OVER w AS c,
+test_plugin_count(v) FILTER (WHERE v > 15) OVER w AS pc
+FROM t
+WINDOW w AS (ORDER BY id ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
+ORDER BY id;
+id	c	pc
+1	1	1
+2	2	2
+3	2	2
+4	2	2
+5	1	1
+SELECT test_plugin_count(v) FILTER (WHERE count(v) > 1) FROM t;
+ERROR HY000: Incorrect usage of aggregate function and FILTER
+CREATE VIEW v1 AS
+SELECT test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t;
+SHOW CREATE VIEW v1;
+View	Create View	character_set_client	collation_connection
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select test_plugin_count(`t`.`v`) FILTER(WHERE `t`.`v` > 15) AS `pc` from `t`	latin1	latin1_swedish_ci
+SELECT * FROM v1;
+pc
+3
+DROP VIEW v1;
+DROP TABLE t;

bugfix-swarm/review_scratch/function_plugin_filter.test

@@ -0,0 +1,38 @@
+--source include/have_udf.inc
+
+--echo #
+--echo # MDEV-41352 SIGSEGV in Item_field::used_tables on a plugin aggregate
+--echo #            with FILTER
+--echo #
+
+CREATE TABLE t (c INT);
+SELECT test_plugin_count(1) FILTER (WHERE c) FROM t;
+DROP TABLE t;
+
+CREATE TABLE t (id INT PRIMARY KEY, g INT, v INT);
+INSERT INTO t VALUES (1,1,10),(2,1,20),(3,2,30),(4,2,NULL),(5,3,50);
+SELECT test_plugin_count(v) FILTER (WHERE v > 15) FROM t;
+SELECT count(v) FILTER (WHERE v > 15) AS c,
+       test_plugin_count(v) FILTER (WHERE v > 15) AS pc,
+       test_plugin_first(v) FILTER (WHERE v > 15) AS pf
+FROM t;
+SELECT g, count(v) FILTER (WHERE id > 1) AS c,
+       test_plugin_count(v) FILTER (WHERE id > 1) AS pc,
+       test_plugin_first(v) FILTER (WHERE id > 1) AS pf
+FROM t GROUP BY g ORDER BY g;
+SELECT count(DISTINCT g) FILTER (WHERE v > 15) AS c,
+       test_plugin_count(DISTINCT g) FILTER (WHERE v > 15) AS pc
+FROM t;
+SELECT id, count(v) FILTER (WHERE v > 15) OVER w AS c,
+       test_plugin_count(v) FILTER (WHERE v > 15) OVER w AS pc
+FROM t
+WINDOW w AS (ORDER BY id ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING)
+ORDER BY id;
+--error ER_WRONG_USAGE
+SELECT test_plugin_count(v) FILTER (WHERE count(v) > 1) FROM t;
+CREATE VIEW v1 AS
+SELECT test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t;
+SHOW CREATE VIEW v1;
+SELECT * FROM v1;
+DROP VIEW v1;
+DROP TABLE t;

bugfix-swarm/review_scratch/function_plugin_filter_rv.result

@@ -0,0 +1,91 @@
+CREATE TABLE t (id INT PRIMARY KEY, g INT, v INT);
+INSERT INTO t VALUES (1,1,10),(2,1,20),(3,2,30),(4,2,NULL),(5,3,50);
+CREATE TABLE t2 (x INT);
+INSERT INTO t2 VALUES (20),(50);
+# prepared statement, executed twice
+PREPARE s FROM 'SELECT test_plugin_count(v) FILTER (WHERE v > ?) FROM t';
+SET @a=15;
+EXECUTE s USING @a;
+test_plugin_count(v) FILTER (WHERE v > ?)
+3
+SET @a=25;
+EXECUTE s USING @a;
+test_plugin_count(v) FILTER (WHERE v > ?)
+2
+DEALLOCATE PREPARE s;
+# stored procedure called twice
+CREATE PROCEDURE p()
+BEGIN
+SELECT g, test_plugin_count(v) FILTER (WHERE v > 15),
+test_plugin_first(v) FILTER (WHERE v > 15) FROM t GROUP BY g ORDER BY g;
+END|
+CALL p();
+g	test_plugin_count(v) FILTER (WHERE v > 15)	test_plugin_first(v) FILTER (WHERE v > 15)
+1	1	20
+2	1	30
+3	1	50
+CALL p();
+g	test_plugin_count(v) FILTER (WHERE v > 15)	test_plugin_first(v) FILTER (WHERE v > 15)
+1	1	20
+2	1	30
+3	1	50
+DROP PROCEDURE p;
+# subquery in filter
+SELECT test_plugin_count(v) FILTER (WHERE v IN (SELECT x FROM t2)) FROM t;
+test_plugin_count(v) FILTER (WHERE v IN (SELECT x FROM t2))
+2
+SELECT count(v) FILTER (WHERE v IN (SELECT x FROM t2)) FROM t;
+count(v) FILTER (WHERE v IN (SELECT x FROM t2))
+2
+# outer reference in filter of subquery aggregate
+SELECT id, (SELECT test_plugin_count(x) FILTER (WHERE x > t.v) FROM t2) AS pc,
+(SELECT count(x) FILTER (WHERE x > t.v) FROM t2) AS c
+FROM t ORDER BY id;
+id	pc	c
+1	2	2
+2	1	1
+3	1	1
+4	0	0
+5	0	0
+# window function in filter -> error
+SELECT test_plugin_count(v) FILTER (WHERE row_number() OVER () > 1) FROM t;
+ERROR HY000: Incorrect usage of window function and FILTER
+# unknown column in filter -> error
+SELECT test_plugin_count(v) FILTER (WHERE nosuch > 1) FROM t;
+ERROR 42S22: Unknown column 'nosuch' in 'SELECT'
+# HAVING and ORDER BY referencing filtered plugin aggregate
+SELECT g, test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t GROUP BY g
+HAVING test_plugin_count(v) FILTER (WHERE v > 15) > 0 ORDER BY pc DESC, g;
+g	pc
+1	1
+2	1
+3	1
+# window, filtered first over sliding frame
+SELECT id, test_plugin_first(v) FILTER (WHERE v > 15) OVER (ORDER BY id) AS pf,
+test_plugin_count(v) FILTER (WHERE id <> 3) OVER (ORDER BY id ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS pc,
+count(v) FILTER (WHERE id <> 3) OVER (ORDER BY id ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS c
+FROM t ORDER BY id;
+id	pf	pc	c
+1	NULL	1	1
+2	20	2	2
+3	20	2	2
+4	20	1	1
+5	20	1	1
+# ROLLUP
+SELECT g, test_plugin_count(v) FILTER (WHERE v > 15) AS pc, count(v) FILTER (WHERE v > 15) AS c FROM t GROUP BY g WITH ROLLUP;
+g	pc	c
+1	1	1
+2	1	1
+3	1	1
+NULL	3	3
+# CREATE TABLE ... SELECT
+CREATE TABLE t3 AS SELECT test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t;
+SELECT * FROM t3;
+pc
+3
+DROP TABLE t3;
+# filter always false / empty
+SELECT test_plugin_count(v) FILTER (WHERE 0), test_plugin_first(v) FILTER (WHERE 0) FROM t;
+test_plugin_count(v) FILTER (WHERE 0)	test_plugin_first(v) FILTER (WHERE 0)
+0	NULL
+DROP TABLE t, t2;

bugfix-swarm/review_scratch/function_plugin_filter_rv.test

@@ -0,0 +1,66 @@
+--source include/have_udf.inc
+
+CREATE TABLE t (id INT PRIMARY KEY, g INT, v INT);
+INSERT INTO t VALUES (1,1,10),(2,1,20),(3,2,30),(4,2,NULL),(5,3,50);
+CREATE TABLE t2 (x INT);
+INSERT INTO t2 VALUES (20),(50);
+
+--echo # prepared statement, executed twice
+PREPARE s FROM 'SELECT test_plugin_count(v) FILTER (WHERE v > ?) FROM t';
+SET @a=15;
+EXECUTE s USING @a;
+SET @a=25;
+EXECUTE s USING @a;
+DEALLOCATE PREPARE s;
+
+--echo # stored procedure called twice
+DELIMITER |;
+CREATE PROCEDURE p()
+BEGIN
+  SELECT g, test_plugin_count(v) FILTER (WHERE v > 15),
+         test_plugin_first(v) FILTER (WHERE v > 15) FROM t GROUP BY g ORDER BY g;
+END|
+DELIMITER ;|
+CALL p();
+CALL p();
+DROP PROCEDURE p;
+
+--echo # subquery in filter
+SELECT test_plugin_count(v) FILTER (WHERE v IN (SELECT x FROM t2)) FROM t;
+SELECT count(v) FILTER (WHERE v IN (SELECT x FROM t2)) FROM t;
+
+--echo # outer reference in filter of subquery aggregate
+SELECT id, (SELECT test_plugin_count(x) FILTER (WHERE x > t.v) FROM t2) AS pc,
+           (SELECT count(x) FILTER (WHERE x > t.v) FROM t2) AS c
+FROM t ORDER BY id;
+
+--echo # window function in filter -> error
+--error ER_WRONG_USAGE
+SELECT test_plugin_count(v) FILTER (WHERE row_number() OVER () > 1) FROM t;
+
+--echo # unknown column in filter -> error
+--error ER_BAD_FIELD_ERROR
+SELECT test_plugin_count(v) FILTER (WHERE nosuch > 1) FROM t;
+
+--echo # HAVING and ORDER BY referencing filtered plugin aggregate
+SELECT g, test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t GROUP BY g
+HAVING test_plugin_count(v) FILTER (WHERE v > 15) > 0 ORDER BY pc DESC, g;
+
+--echo # window, filtered first over sliding frame
+SELECT id, test_plugin_first(v) FILTER (WHERE v > 15) OVER (ORDER BY id) AS pf,
+           test_plugin_count(v) FILTER (WHERE id <> 3) OVER (ORDER BY id ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS pc,
+           count(v) FILTER (WHERE id <> 3) OVER (ORDER BY id ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS c
+FROM t ORDER BY id;
+
+--echo # ROLLUP
+SELECT g, test_plugin_count(v) FILTER (WHERE v > 15) AS pc, count(v) FILTER (WHERE v > 15) AS c FROM t GROUP BY g WITH ROLLUP;
+
+--echo # CREATE TABLE ... SELECT
+CREATE TABLE t3 AS SELECT test_plugin_count(v) FILTER (WHERE v > 15) AS pc FROM t;
+SELECT * FROM t3;
+DROP TABLE t3;
+
+--echo # filter always false / empty
+SELECT test_plugin_count(v) FILTER (WHERE 0), test_plugin_first(v) FILTER (WHERE 0) FROM t;
+
+DROP TABLE t, t2;

include/mysql/plugin_function.h

@@ -29,6 +29,15 @@
 
 /*
   API for function plugins. (MariaDB_FUNCTION_PLUGIN)
+
+  An aggregate function's Create_func must create an Item_sum_plugin descendant.
+  Aggregate implementations consume rows in add_row() and use aggregation_arg()
+  to read values, including values replayed by DISTINCT. FILTER (WHERE ...) is
+  applied by the server: add_row() and remove_row() see only passing rows.
+  DISTINCT does not guarantee replay order; order-sensitive implementations
+  must override supports_distinct() to return false. Aggregates can implement
+  supports_removal() and remove_row() for moving window frames, and
+  val_native() to preserve a pluggable result type.
 */
 #define MariaDB_FUNCTION_INTERFACE_VERSION (MYSQL_VERSION_ID << 8)