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MDEV-40803 Recursive CTE loses a row when its increment table converts #5563

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MDEV-40803 Recursive CTE loses a row when its increment table converts
arcivanov Aug 18, 2026
0c449dc
Cover converting a result table whose index has been disabled
arcivanov Aug 18, 2026
2f58821
Drop the view left behind by cte_update_delete.test
arcivanov Aug 18, 2026
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227 changes: 227 additions & 0 deletions mysql-test/main/cte_recursive.result
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Original file line number Diff line number Diff line change
Expand Up @@ -6246,3 +6246,230 @@ SELECT 1 > ( WITH cte AS ( SELECT 1 FROM x ) SELECT 1 FROM cte ) )
SELECT 1 FROM x;
ERROR HY000: Restrictions imposed on recursive definitions are violated for table 'x'
# End of 10.11 tests
#
# Recursive CTE loses a row when the increment table is converted
# into an on-disk temporary table
#
CREATE TABLE t1 (n INT, pad CHAR(255) CHARACTER SET utf8mb4);
INSERT INTO t1 SELECT seq, REPEAT('x',255) FROM seq_1_to_64;
SET @save_tmp_memory_table_size= @@tmp_memory_table_size;
SET @save_max_heap_table_size= @@max_heap_table_size;
# Each query below is run twice. The first run leaves the increment
# table in memory, the second forces it to be converted to an on-disk
# table while it is being filled. Both runs must return the same rows.
#
# The increment table overflows while the anchor part fills it
#
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
FLUSH STATUS;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
# 0 = no temporary table was converted
SELECT VARIABLE_VALUE > 0 AS converted FROM information_schema.SESSION_STATUS
WHERE VARIABLE_NAME = 'Created_tmp_disk_tables';
converted
0
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
FLUSH STATUS;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
# 1 = a temporary table was converted
SELECT VARIABLE_VALUE > 0 AS converted FROM information_schema.SESSION_STATUS
WHERE VARIABLE_NAME = 'Created_tmp_disk_tables';
converted
1
#
# The increment table overflows during a recursive step
#
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, pad FROM t1 WHERE n = 1
UNION ALL
SELECT r.lvl+1, t1.pad FROM r, t1 WHERE r.lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads
1 1 1
2 64 64
3 4096 4096
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, pad FROM t1 WHERE n = 1
UNION ALL
SELECT r.lvl+1, t1.pad FROM r, t1 WHERE r.lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads
1 1 1
2 64 64
3 4096 4096
#
# The same, for a CTE that eliminates duplicates
#
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
#
# The same, when the result table's key does not fit an on-disk table
# and is replaced by a unique constraint. The result table's record
# then carries a trailing hash field that the increment table's record
# does not have, so the two records are of different length.
#
CREATE TABLE t2 (n INT,
p1 CHAR(200) CHARACTER SET utf8mb4,
p2 CHAR(200) CHARACTER SET utf8mb4,
p3 CHAR(200) CHARACTER SET utf8mb4);
INSERT INTO t2
SELECT seq, REPEAT('a',200), REPEAT('b',200), REPEAT('c',200) FROM seq_1_to_64;
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, p1, p2, p3 FROM t2
UNION
SELECT lvl+1, n, p1, p2, p3 FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(p3) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, p1, p2, p3 FROM t2
UNION
SELECT lvl+1, n, p1, p2, p3 FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(p3) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
DROP TABLE t2;
#
# A prepared statement re-executed after its increment table was
# converted on an earlier execution
#
PREPARE s FROM "
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM r GROUP BY lvl ORDER BY lvl";
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
EXECUTE s;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
EXECUTE s;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
EXECUTE s;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
DROP PREPARE s;
#
# Mutually recursive CTEs
#
SET SESSION tmp_memory_table_size= 16777216;
SET SESSION max_heap_table_size= 16777216;
WITH RECURSIVE
a AS (SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM b WHERE lvl < 4),
b AS (SELECT lvl, n, pad FROM a)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM a GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
4 64 64 2080
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
WITH RECURSIVE
a AS (SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM b WHERE lvl < 4),
b AS (SELECT lvl, n, pad FROM a)
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM a GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
4 64 64 2080
#
# INSERT ... SELECT, which takes a different warning-handling path
# when the increment table is filled
#
CREATE TABLE t3 (lvl INT, n INT, pad CHAR(255) CHARACTER SET utf8mb4);
SET SESSION tmp_memory_table_size= 16384;
SET SESSION max_heap_table_size= 16384;
INSERT INTO t3
WITH RECURSIVE r AS
(SELECT 1 AS lvl, n, pad FROM t1
UNION ALL
SELECT lvl+1, n, pad FROM r WHERE lvl < 3)
SELECT lvl, n, pad FROM r;
SELECT lvl, COUNT(*) AS cnt, COUNT(pad) AS pads, SUM(n) AS sum_n
FROM t3 GROUP BY lvl ORDER BY lvl;
lvl cnt pads sum_n
1 64 64 2080
2 64 64 2080
3 64 64 2080
DROP TABLE t3;
SET SESSION tmp_memory_table_size= @save_tmp_memory_table_size;
SET SESSION max_heap_table_size= @save_max_heap_table_size;
DROP TABLE t1;
# End of 13.1 tests
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