GIF89a;
Mini Shell
Mini Shell
SET optimizer_trace_max_mem_size=1048576;
SET optimizer_trace="enabled=on,one_line=off";
SET end_markers_in_json="on";
CREATE TABLE tmp (
pk INT PRIMARY KEY AUTO_INCREMENT,
col1 CHAR (1)
);
INSERT INTO tmp(col1) VALUES ('a'),('b'),('c'),('d'),('e'),('f'),('g'),('h');
CREATE TABLE t1 (
uniq VARCHAR(10),
col1 VARCHAR(10),
col2 VARCHAR(1024)
);
INSERT INTO t1 SELECT pk, col1, col1 FROM tmp;
SELECT uniq, col1 FROM t1 GROUP BY col2,uniq LIMIT 3;
uniq col1
1 a
2 b
3 c
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
SELECT uniq, col1 FROM t1 GROUP BY col2,uniq LIMIT 3 {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`uniq` AS `uniq`,`t1`.`col1` AS `col1` from `t1` group by `t1`.`col2`,`t1`.`uniq` limit 3"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`t1`",
"table_scan": {
"rows": 8,
"cost": 2
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 8,
"cost": 3.6391,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 3.6391,
"rows_for_plan": 8,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"clause_processing": {
"clause": "GROUP BY",
"original_clause": "`t1`.`col2`,`t1`.`uniq`",
"items": [
{
"item": "`t1`.`col2`"
},
{
"item": "`t1`.`uniq`"
}
] /* items */,
"resulting_clause_is_simple": true,
"resulting_clause": "`t1`.`col2`,`t1`.`uniq`"
} /* clause_processing */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1054,
"key_length": 1040,
"unique_constraint": true,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"filesort_information": [
{
"direction": "asc",
"table": "intermediate_tmp_table",
"field": "col2"
},
{
"direction": "asc",
"table": "intermediate_tmp_table",
"field": "uniq"
}
] /* filesort_information */,
"filesort_priority_queue_optimization": {
"limit": 3,
"rows_estimate": 18,
"row_size": 1042,
"memory_available": 262144,
"chosen": true
} /* filesort_priority_queue_optimization */,
"filesort_execution": [
] /* filesort_execution */,
"filesort_summary": {
"rows": 4,
"examined_rows": 8,
"number_of_tmp_files": 0,
"sort_buffer_size": 4200,
"sort_mode": "<sort_key, rowid>"
} /* filesort_summary */
}
] /* steps */
} /* join_execution */
}
] /* steps */
} 0 0
SELECT uniq, col1, col2 FROM t1 GROUP BY uniq ;
uniq col1 col2
1 a a
2 b b
3 c c
4 d d
5 e e
6 f f
7 g g
8 h h
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
SELECT uniq, col1, col2 FROM t1 GROUP BY uniq {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`uniq` AS `uniq`,`t1`.`col1` AS `col1`,`t1`.`col2` AS `col2` from `t1` group by `t1`.`uniq`"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`t1`",
"table_scan": {
"rows": 8,
"cost": 2
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 8,
"cost": 3.6391,
"chosen": true,
"use_tmp_table": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 3.6391,
"rows_for_plan": 8,
"sort_cost": 8,
"new_cost_for_plan": 11.639,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"clause_processing": {
"clause": "GROUP BY",
"original_clause": "`t1`.`uniq`",
"items": [
{
"item": "`t1`.`uniq`"
}
] /* items */,
"resulting_clause_is_simple": true,
"resulting_clause": "`t1`.`uniq`"
} /* clause_processing */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1050,
"key_length": 13,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 998
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"filesort_information": [
{
"direction": "asc",
"table": "intermediate_tmp_table",
"field": "uniq"
}
] /* filesort_information */,
"filesort_priority_queue_optimization": {
"usable": false,
"cause": "not applicable (no LIMIT)"
} /* filesort_priority_queue_optimization */,
"filesort_execution": [
] /* filesort_execution */,
"filesort_summary": {
"rows": 8,
"examined_rows": 8,
"number_of_tmp_files": 0,
"sort_buffer_size": 486,
"sort_mode": "<sort_key, rowid>"
} /* filesort_summary */
}
] /* steps */
} /* join_execution */
}
] /* steps */
} 0 0
select @@tmp_table_size;
@@tmp_table_size
16777216
SET @old_size= @@tmp_table_size;
SET SESSION tmp_table_size= 1024;
INSERT INTO t1 SELECT pk+8, col1, col1 FROM tmp;
SELECT uniq, col1, col2 FROM t1 GROUP BY uniq;
uniq col1 col2
1 a a
10 b b
11 c c
12 d d
13 e e
14 f f
15 g g
16 h h
2 b b
3 c c
4 d d
5 e e
6 f f
7 g g
8 h h
9 a a
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
SELECT uniq, col1, col2 FROM t1 GROUP BY uniq {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`uniq` AS `uniq`,`t1`.`col1` AS `col1`,`t1`.`col2` AS `col2` from `t1` group by `t1`.`uniq`"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`t1`",
"table_scan": {
"rows": 16,
"cost": 2
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 16,
"cost": 5.2781,
"chosen": true,
"use_tmp_table": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 5.2781,
"rows_for_plan": 16,
"sort_cost": 16,
"new_cost_for_plan": 21.278,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"clause_processing": {
"clause": "GROUP BY",
"original_clause": "`t1`.`uniq`",
"items": [
{
"item": "`t1`.`uniq`"
}
] /* items */,
"resulting_clause_is_simple": true,
"resulting_clause": "`t1`.`uniq`"
} /* clause_processing */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1050,
"key_length": 13,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"converting_tmp_table_to_myisam": {
"cause": "memory_table_size_exceeded",
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1050,
"key_length": 13,
"unique_constraint": false,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* converting_tmp_table_to_myisam */
},
{
"filesort_information": [
{
"direction": "asc",
"table": "intermediate_tmp_table",
"field": "uniq"
}
] /* filesort_information */,
"filesort_priority_queue_optimization": {
"usable": false,
"cause": "not applicable (no LIMIT)"
} /* filesort_priority_queue_optimization */,
"filesort_execution": [
] /* filesort_execution */,
"filesort_summary": {
"rows": 16,
"examined_rows": 16,
"number_of_tmp_files": 0,
"sort_buffer_size": 650,
"sort_mode": "<sort_key, rowid>"
} /* filesort_summary */
}
] /* steps */
} /* join_execution */
}
] /* steps */
} 0 0
SET GLOBAL tmp_table_size= @old_size;
SELECT pool_id FROM information_schema.innodb_buffer_page LIMIT 1;
pool_id
0
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
SELECT pool_id FROM information_schema.innodb_buffer_page LIMIT 1 {
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"row_length": 6852,
"key_length": 0,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `information_schema`.`innodb_buffer_page`.`POOL_ID` AS `pool_id` from `information_schema`.`innodb_buffer_page` limit 1"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"table_dependencies": [
{
"table": "`information_schema`.`innodb_buffer_page`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`information_schema`.`innodb_buffer_page`",
"table_scan": {
"rows": 2,
"cost": 10
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`information_schema`.`innodb_buffer_page`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 2,
"cost": 10.5,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 10.5,
"rows_for_plan": 2,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`information_schema`.`innodb_buffer_page`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`information_schema`.`innodb_buffer_page`",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"converting_tmp_table_to_myisam": {
"cause": "memory_table_size_exceeded",
"tmp_table_info": {
"table": "`information_schema`.`innodb_buffer_page`",
"row_length": 6852,
"key_length": 0,
"unique_constraint": false,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* converting_tmp_table_to_myisam */
}
] /* steps */
} /* join_execution */
}
] /* steps */
} 0 0
DROP TABLE t1, tmp;
#
# Bug#17231940: THE OPTIMIZER STILL USES FIXED LENGTH TEMPORARY TABLES
# ON DISK
#
CREATE TABLE t1 (
c1 INT AUTO_INCREMENT PRIMARY KEY,
c2 VARCHAR(250)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO t1(c2) VALUES ('b'),('b');
INSERT INTO t1(c2) SELECT t1.c2 FROM t1, t1 t2, t1 t3, t1 t4, t1 t5, t1 t6;
SET @@max_heap_table_size=1;
Warnings:
Warning 1292 Truncated incorrect max_heap_table_size value: '1'
SET @@group_concat_max_len= 500;
SELECT c1,GROUP_CONCAT(c2) cc FROM
(SELECT * FROM t1 UNION SELECT c1, 'a' FROM t1) tt
GROUP BY c1
ORDER BY cc;
c1 cc
1 b,a
2 b,a
3 b,a
4 b,a
5 b,a
6 b,a
7 b,a
8 b,a
9 b,a
10 b,a
11 b,a
12 b,a
13 b,a
14 b,a
15 b,a
16 b,a
17 b,a
18 b,a
19 b,a
20 b,a
21 b,a
22 b,a
23 b,a
24 b,a
25 b,a
26 b,a
27 b,a
28 b,a
29 b,a
30 b,a
31 b,a
32 b,a
33 b,a
34 b,a
35 b,a
36 b,a
37 b,a
38 b,a
39 b,a
40 b,a
41 b,a
42 b,a
43 b,a
44 b,a
45 b,a
46 b,a
47 b,a
48 b,a
49 b,a
50 b,a
51 b,a
52 b,a
53 b,a
54 b,a
55 b,a
56 b,a
57 b,a
58 b,a
59 b,a
60 b,a
61 b,a
62 b,a
63 b,a
64 b,a
65 b,a
66 b,a
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
SELECT c1,GROUP_CONCAT(c2) cc FROM
(SELECT * FROM t1 UNION SELECT c1, 'a' FROM t1) tt
GROUP BY c1
ORDER BY cc {
"steps": [
{
"join_preparation": {
"select#": 2,
"steps": [
{
"expanded_query": "/* select#2 */ select `t1`.`c1` AS `c1`,`t1`.`c2` AS `c2` from `t1`"
}
] /* steps */
} /* join_preparation */
},
{
"join_preparation": {
"select#": 3,
"steps": [
{
"expanded_query": "/* select#3 */ select `t1`.`c1` AS `c1`,'a' AS `a` from `t1`"
}
] /* steps */
} /* join_preparation */
},
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 757,
"key_length": 757,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `tt`.`c1` AS `c1`,group_concat(`tt`.`c2` separator ',') AS `cc` from (/* select#2 */ select `t1`.`c1` AS `c1`,`t1`.`c2` AS `c2` from `t1` union /* select#3 */ select `t1`.`c1` AS `c1`,'a' AS `a` from `t1`) `tt` group by `tt`.`c1` order by `cc`"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"join_optimization": {
"select#": 2,
"steps": [
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`t1`",
"table_scan": {
"rows": 66,
"cost": 1
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 66,
"cost": 14.2,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 14.2,
"rows_for_plan": 66,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_optimization": {
"select#": 3,
"steps": [
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "`t1`",
"table_scan": {
"rows": 66,
"cost": 1
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 66,
"cost": 14.2,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 14.2,
"rows_for_plan": 66,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "index_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"table_dependencies": [
{
"table": " `tt`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": " `tt`",
"table_scan": {
"rows": 132,
"cost": 16
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": " `tt`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 132,
"cost": 43,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 43,
"rows_for_plan": 132,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": " `tt`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"clause_processing": {
"clause": "ORDER BY",
"original_clause": "`cc`",
"items": [
{
"item": "group_concat(`tt`.`c2` separator ',')"
}
] /* items */,
"resulting_clause_is_simple": false,
"resulting_clause": "`cc`"
} /* clause_processing */
},
{
"clause_processing": {
"clause": "GROUP BY",
"original_clause": "`tt`.`c1`",
"items": [
{
"item": "`tt`.`c1`"
}
] /* items */,
"resulting_clause_is_simple": true,
"resulting_clause": "`tt`.`c1`"
} /* clause_processing */
},
{
"refine_plan": [
{
"table": " `tt`",
"access_type": "table_scan"
}
] /* refine_plan */
},
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 753,
"key_length": 0,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"table": " `tt`",
"row_length": 757,
"key_length": 0,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"join_execution": {
"select#": 2,
"steps": [
{
"converting_tmp_table_to_myisam": {
"cause": "memory_table_size_exceeded",
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 757,
"key_length": 757,
"unique_constraint": false,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* converting_tmp_table_to_myisam */
}
] /* steps */
} /* join_execution */
},
{
"join_execution": {
"select#": 3,
"steps": [
] /* steps */
} /* join_execution */
},
{
"join_preparation": {
"select#": "fake",
"steps": [
{
"expanded_query": "/* select#fake */ select `c1` AS `c1`,`c2` AS `c2` from dual"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": "fake",
"steps": [
{
"table_dependencies": [
{
"table": "``.``",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"rows_estimation": [
{
"table": "``.``",
"table_scan": {
"rows": 132,
"cost": 2
} /* table_scan */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "``.``",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "scan",
"rows": 132,
"cost": 29.045,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 29.045,
"rows_for_plan": 132,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": null,
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "``.``",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "``.``",
"access_type": "table_scan"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_execution": {
"select#": "fake",
"steps": [
{
"converting_tmp_table_to_myisam": {
"cause": "memory_table_size_exceeded",
"tmp_table_info": {
"table": " `tt`",
"row_length": 757,
"key_length": 0,
"unique_constraint": false,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* converting_tmp_table_to_myisam */
}
] /* steps */
} /* join_execution */
},
{
"filesort_information": [
{
"direction": "asc",
"table": " `tt`",
"field": "c1"
}
] /* filesort_information */,
"filesort_priority_queue_optimization": {
"usable": false,
"cause": "not applicable (no LIMIT)"
} /* filesort_priority_queue_optimization */,
"filesort_execution": [
] /* filesort_execution */,
"filesort_summary": {
"rows": 132,
"examined_rows": 132,
"number_of_tmp_files": 0,
"sort_buffer_size": 109482,
"sort_mode": "<sort_key, additional_fields>"
} /* filesort_summary */
},
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1507,
"key_length": 0,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 1
} /* tmp_table_info */
} /* creating_tmp_table */
},
{
"converting_tmp_table_to_myisam": {
"cause": "memory_table_size_exceeded",
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 1507,
"key_length": 0,
"unique_constraint": false,
"location": "disk (MyISAM)",
"record_format": "packed"
} /* tmp_table_info */
} /* converting_tmp_table_to_myisam */
},
{
"filesort_information": [
{
"direction": "asc",
"table": "intermediate_tmp_table",
"field": "cc"
}
] /* filesort_information */,
"filesort_priority_queue_optimization": {
"usable": false,
"cause": "not applicable (no LIMIT)"
} /* filesort_priority_queue_optimization */,
"filesort_execution": [
] /* filesort_execution */,
"filesort_summary": {
"rows": 66,
"examined_rows": 66,
"number_of_tmp_files": 0,
"sort_buffer_size": 77140,
"sort_mode": "<sort_key, rowid>"
} /* filesort_summary */
}
] /* steps */
} /* join_execution */
}
] /* steps */
} 0 0
DROP TABLE t1;
#
./BlackJoker Mini Shell 1.0