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";
SET eq_range_index_dive_limit=default;
SELECT @@eq_range_index_dive_limit;
@@eq_range_index_dive_limit
10
CREATE TABLE t1 (
a INT,
b INT,
KEY (a,b)
);
INSERT INTO t1 VALUES (1,1), (2,2), (3,3);
INSERT INTO t1 VALUES (4,1), (4,2), (4,3);
INSERT INTO t1 VALUES (5,1), (5,2), (5,3);
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A NULL NULL NULL YES BTREE
t1 1 a 2 b A NULL NULL NULL YES BTREE
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 4 NULL NULL YES BTREE
t1 1 a 2 b A 9 NULL NULL YES BTREE
#####
# Apply knowledge about the statistics (each index value for
# the first key part has an estimate of 2 rows) to ensure that
# index statistics kicks in correctly.
#####
# Index dives are done, giving correct estimate of 3 records
EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 3 Using where; Using index
SET eq_range_index_dive_limit=3;
SELECT @@eq_range_index_dive_limit;
@@eq_range_index_dive_limit
3
SET SESSION DEBUG="+d,crash_records_in_range";
# Index statistics kicks in, giving incorrect estimate of 3x2=6 records
EXPLAIN SELECT * FROM t1 WHERE a IN (1,2,3);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 6 Using where; Using index
SELECT * FROM t1 WHERE a IN (1,2,3);
a b
1 1
2 2
3 3
SET SESSION DEBUG="-d,crash_records_in_range";
#####
# Below: A number of tests to verify that the number of equality ranges
# are counted correctly
#####
# 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 5 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` = 1))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` = 1))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or multiple equal(1, `t1`.`a`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or multiple equal(1, `t1`.`a`))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or multiple equal(1, `t1`.`a`))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"1 <= a <= 1",
"5 <= a <= 5",
"10 < a"
] /* ranges */,
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 5,
"cost": 2.139,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 5,
"ranges": [
"1 <= a <= 1",
"5 <= a <= 5",
"10 < a"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 5,
"cost_for_plan": 2.139,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "range",
"rows": 5,
"cost": 3.139,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 3.139,
"rows_for_plan": 5,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` = 1))",
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` = 1))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
# 3 equality ranges: should use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1,2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 7 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 OR a>10 OR a IN (1,2) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "(multiple equal(5, `t1`.`a`) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"1 <= a <= 1",
"2 <= a <= 2",
"5 <= a <= 5",
"10 < a"
] /* ranges */,
"index_dives_for_eq_ranges": false,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 7,
"cost": 2.6035,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 7,
"ranges": [
"1 <= a <= 1",
"2 <= a <= 2",
"5 <= a <= 5",
"10 < a"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 7,
"cost_for_plan": 2.6035,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "range",
"rows": 7,
"cost": 4.0035,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 4.0035,
"rows_for_plan": 7,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))",
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` = 5) or (`t1`.`a` > 10) or (`t1`.`a` in (1,2)))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
# 3 equality ranges: should use index statistics
SET SESSION DEBUG="+d,crash_records_in_range";
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b=4);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 10 NULL 3 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b=4) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)) and multiple equal(5, `t1`.`a`))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
{
"table": "`t1`",
"field": "a",
"equals": "5",
"null_rejecting": false
}
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3",
"5 <= a <= 5 AND 4 <= b <= 4"
] /* ranges */,
"index_dives_for_eq_ranges": false,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 3,
"cost": 1.6745,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 3,
"ranges": [
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3",
"5 <= a <= 5 AND 4 <= b <= 4"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 3,
"cost_for_plan": 1.6745,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "a",
"rows": 3,
"cost": 1.6645,
"chosen": true
},
{
"access_type": "range",
"rows": 3,
"cost": 2.2745,
"chosen": false
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 1.6645,
"rows_for_plan": 3,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))",
"attached_conditions_computation": [
{
"access_type_changed": {
"table": "`t1`",
"index": "a",
"old_type": "ref",
"new_type": "range",
"cause": "uses_more_keyparts"
} /* access_type_changed */
}
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
SET SESSION DEBUG="-d,crash_records_in_range";
# 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b>4);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 10 NULL 3 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b>4) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` > 4)))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` > 4)))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or (`t1`.`b` > 4)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or (`t1`.`b` > 4)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or (`t1`.`b` > 4)) and multiple equal(5, `t1`.`a`))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
{
"table": "`t1`",
"field": "a",
"equals": "5",
"null_rejecting": false
}
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3",
"5 <= a <= 5 AND 4 < b"
] /* ranges */,
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 3,
"cost": 1.6745,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 3,
"ranges": [
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3",
"5 <= a <= 5 AND 4 < b"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 3,
"cost_for_plan": 1.6745,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "a",
"rows": 3,
"cost": 1.6645,
"chosen": true
},
{
"access_type": "range",
"rows": 3,
"cost": 2.2745,
"chosen": false
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 1.6645,
"rows_for_plan": 3,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` > 4)))",
"attached_conditions_computation": [
{
"access_type_changed": {
"table": "`t1`",
"index": "a",
"old_type": "ref",
"new_type": "range",
"cause": "uses_more_keyparts"
} /* access_type_changed */
}
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` > 4)))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
# 2 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b IS NULL);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 10 NULL 3 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 AND (b=2 OR b=3 OR b IS NULL) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or isnull(`t1`.`b`)))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or isnull(`t1`.`b`)))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or isnull(`t1`.`b`)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or isnull(`t1`.`b`)) and multiple equal(5, `t1`.`a`))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "((multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or isnull(`t1`.`b`)) and multiple equal(5, `t1`.`a`))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
{
"table": "`t1`",
"field": "a",
"equals": "5",
"null_rejecting": false
}
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"5 <= a <= 5 AND NULL <= b <= NULL",
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3"
] /* ranges */,
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 3,
"cost": 1.6745,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 3,
"ranges": [
"5 <= a <= 5 AND NULL <= b <= NULL",
"5 <= a <= 5 AND 2 <= b <= 2",
"5 <= a <= 5 AND 3 <= b <= 3"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 3,
"cost_for_plan": 1.6745,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "a",
"rows": 3,
"cost": 1.6645,
"chosen": true
},
{
"access_type": "range",
"rows": 3,
"cost": 2.2745,
"chosen": false
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 1.6645,
"rows_for_plan": 3,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or isnull(`t1`.`b`)))",
"attached_conditions_computation": [
{
"access_type_changed": {
"table": "`t1`",
"index": "a",
"old_type": "ref",
"new_type": "range",
"cause": "uses_more_keyparts"
} /* access_type_changed */
}
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` = 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or isnull(`t1`.`b`)))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
# 0 equality ranges: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a>5 AND (b=2 OR b=3 OR b=4);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a>5 AND (b=2 OR b=3 OR b=4) {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where ((`t1`.`a` > 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`t1`.`a` > 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((`t1`.`a` > 5) and (multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((`t1`.`a` > 5) and (multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "((`t1`.`a` > 5) and (multiple equal(2, `t1`.`b`) or multiple equal(3, `t1`.`b`) or multiple equal(4, `t1`.`b`)))"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"5 < a"
] /* ranges */,
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 1,
"cost": 2.21,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 1,
"ranges": [
"5 < a"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 1,
"cost_for_plan": 2.21,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "range",
"rows": 1,
"cost": 2.41,
"chosen": true
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 2.41,
"rows_for_plan": 1,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`t1`.`a` > 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))",
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": "((`t1`.`a` > 5) and ((`t1`.`b` = 2) or (`t1`.`b` = 3) or (`t1`.`b` = 4)))"
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`",
"access_type": "range"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
SET eq_range_index_dive_limit=0;
# 1 equality range: should not use index statistics
EXPLAIN SELECT * FROM t1 WHERE a=5;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 3 Using index
SELECT * FROM information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT * FROM t1 WHERE a=5 {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `t1`.`a` AS `a`,`t1`.`b` AS `b` from `t1` where (`t1`.`a` = 5)"
}
] /* steps */
} /* join_preparation */
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "(`t1`.`a` = 5)",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "multiple equal(5, `t1`.`a`)"
},
{
"transformation": "constant_propagation",
"resulting_condition": "multiple equal(5, `t1`.`a`)"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "multiple equal(5, `t1`.`a`)"
}
] /* steps */
} /* condition_processing */
},
{
"table_dependencies": [
{
"table": "`t1`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
] /* depends_on_map_bits */
}
] /* table_dependencies */
},
{
"ref_optimizer_key_uses": [
{
"table": "`t1`",
"field": "a",
"equals": "5",
"null_rejecting": false
}
] /* ref_optimizer_key_uses */
},
{
"rows_estimation": [
{
"table": "`t1`",
"range_analysis": {
"table_scan": {
"rows": 9,
"cost": 5.9198
} /* table_scan */,
"potential_range_indices": [
{
"index": "a",
"usable": true,
"key_parts": [
"a",
"b"
] /* key_parts */
}
] /* potential_range_indices */,
"best_covering_index_scan": {
"index": "a",
"cost": 3.0581,
"chosen": true
} /* best_covering_index_scan */,
"setup_range_conditions": [
] /* setup_range_conditions */,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} /* group_index_range */,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "a",
"ranges": [
"5 <= a <= 5"
] /* ranges */,
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": true,
"rows": 3,
"cost": 1.6745,
"chosen": true
}
] /* range_scan_alternatives */,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
} /* analyzing_roworder_intersect */
} /* analyzing_range_alternatives */,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "a",
"rows": 3,
"ranges": [
"5 <= a <= 5"
] /* ranges */
} /* range_access_plan */,
"rows_for_plan": 3,
"cost_for_plan": 1.6745,
"chosen": true
} /* chosen_range_access_summary */
} /* range_analysis */
}
] /* rows_estimation */
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] /* plan_prefix */,
"table": "`t1`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "a",
"rows": 3,
"cost": 1.6645,
"chosen": true
},
{
"access_type": "range",
"cause": "heuristic_index_cheaper",
"chosen": false
}
] /* considered_access_paths */
} /* best_access_path */,
"cost_for_plan": 1.6645,
"rows_for_plan": 3,
"chosen": true
}
] /* considered_execution_plans */
},
{
"attaching_conditions_to_tables": {
"original_condition": "(`t1`.`a` = 5)",
"attached_conditions_computation": [
] /* attached_conditions_computation */,
"attached_conditions_summary": [
{
"table": "`t1`",
"attached": null
}
] /* attached_conditions_summary */
} /* attaching_conditions_to_tables */
},
{
"refine_plan": [
{
"table": "`t1`"
}
] /* refine_plan */
}
] /* steps */
} /* join_optimization */
},
{
"join_explain": {
"select#": 1,
"steps": [
] /* steps */
} /* join_explain */
}
] /* steps */
} 0 0
DROP TABLE t1;
SET eq_range_index_dive_limit=default;
./BlackJoker Mini Shell 1.0