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Add variable to disable full table/index scans
Summary: There are cases where it is always unacceptable for a client to be doing full table scans. To prevent this from happening, add a new variable optimizer_full_scan. When it is turned off, it will return a new error code ER_FULL_SCAN_DISABLED. For best results, use with optimizer_force_index_for_range. Currently, it does not fallback to alternative plans because we check at the end of query planning. Reviewed By: hermanlee Differential Revision: D7528820 fbshipit-source-id: 94fcd07
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| set @orig_optimizer_full_scan = @@optimizer_full_scan; | ||
| set @orig_optimizer_force_index_for_range = @@optimizer_force_index_for_range; | ||
| create table t (i int, j int, key(i)); | ||
| insert into t values (1, 1); | ||
| insert into t values (1, 2); | ||
| insert into t values (2, 1); | ||
| insert into t values (2, 2); | ||
| insert into t values (3, 1); | ||
| insert into t values (3, 2); | ||
| analyze table t; | ||
| Table Op Msg_type Msg_text | ||
| test.t analyze status OK | ||
| # Basic tests | ||
| explain select * from t; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t ALL NULL NULL NULL NULL # NULL | ||
| set optimizer_full_scan = off; | ||
| select * from t; | ||
| ERROR HY000: Full table/index scan is disabled | ||
| set optimizer_full_scan = on; | ||
| select * from t; | ||
| i j | ||
| 1 1 | ||
| 1 2 | ||
| 2 1 | ||
| 2 2 | ||
| 3 1 | ||
| 3 2 | ||
| explain select * from t force index (i); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t ALL NULL NULL NULL NULL # NULL | ||
| set optimizer_full_scan = off; | ||
| select i from t force index (i); | ||
| ERROR HY000: Full table/index scan is disabled | ||
| set optimizer_full_scan = on; | ||
| select i from t force index (i); | ||
| i | ||
| 1 | ||
| 1 | ||
| 2 | ||
| 2 | ||
| 3 | ||
| 3 | ||
| explain select * from t a, t b where a.i = b.i; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE a ALL i NULL NULL NULL # NULL | ||
| 1 SIMPLE b ALL i NULL NULL NULL # Using where; Using join buffer (Block Nested Loop) | ||
| set optimizer_full_scan = off; | ||
| select * from t a, t b where a.i = b.i; | ||
| ERROR HY000: Full table/index scan is disabled | ||
| set optimizer_full_scan = on; | ||
| select * from t a, t b where a.i = b.i; | ||
| i j i j | ||
| 1 1 1 1 | ||
| 1 2 1 1 | ||
| 1 1 1 2 | ||
| 1 2 1 2 | ||
| 2 1 2 1 | ||
| 2 2 2 1 | ||
| 2 1 2 2 | ||
| 2 2 2 2 | ||
| 3 1 3 1 | ||
| 3 2 3 1 | ||
| 3 1 3 2 | ||
| 3 2 3 2 | ||
| explain select * from t a straight_join t b where a.i = 10; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE a ref i i 5 const # NULL | ||
| 1 SIMPLE b ALL NULL NULL NULL NULL # Using join buffer (Block Nested Loop) | ||
| set optimizer_full_scan = off; | ||
| select * from t a straight_join t b where a.i = 10; | ||
| ERROR HY000: Full table/index scan is disabled | ||
| set optimizer_full_scan = on; | ||
| select * from t a straight_join t b where a.i = 10; | ||
| i j i j | ||
| # Test integration with optimizer_force_index_for_range | ||
| alter table t drop index i, add primary key (i, j); | ||
| # Test range plans | ||
| set optimizer_force_index_for_range = on; | ||
| set optimizer_full_scan = off; | ||
| explain select i from t where i in (1, 2, 3) and j in (1, 2); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t index PRIMARY PRIMARY 8 NULL # Using where; Using index | ||
| select i from t where i in (1, 2, 3) and j in (1, 2); | ||
| ERROR HY000: Full table/index scan is disabled | ||
| explain select i from t force index (primary) where i in (1, 2, 3) and j in (1, 2); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t range PRIMARY PRIMARY 8 NULL # Using where; Using index | ||
| select i from t force index (primary) where i in (1, 2, 3) and j in (1, 2); | ||
| i | ||
| 1 | ||
| 1 | ||
| 2 | ||
| 2 | ||
| 3 | ||
| 3 | ||
| drop table t; | ||
| set optimizer_full_scan = @orig_optimizer_full_scan; | ||
| set optimizer_force_index_for_range = @orig_optimizer_force_index_for_range; |
93 changes: 93 additions & 0 deletions
93
mysql-test/suite/sys_vars/r/optimizer_full_scan_basic.result
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,93 @@ | ||
| SET @session_start_value = @@session.optimizer_full_scan; | ||
| SELECT @session_start_value; | ||
| @session_start_value | ||
| 1 | ||
| SET @global_start_value = @@global.optimizer_full_scan; | ||
| SELECT @global_start_value; | ||
| @global_start_value | ||
| 1 | ||
| SET @@session.optimizer_full_scan = 0; | ||
| SET @@session.optimizer_full_scan = DEFAULT; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET @@session.optimizer_full_scan = 1; | ||
| SET @@session.optimizer_full_scan = DEFAULT; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET optimizer_full_scan = 1; | ||
| SELECT @@optimizer_full_scan; | ||
| @@optimizer_full_scan | ||
| 1 | ||
| SELECT session.optimizer_full_scan; | ||
| ERROR 42S02: Unknown table 'session' in field list | ||
| SELECT local.optimizer_full_scan; | ||
| ERROR 42S02: Unknown table 'local' in field list | ||
| SET session optimizer_full_scan = 0; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 0 | ||
| SET @@session.optimizer_full_scan = 0; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 0 | ||
| SET @@session.optimizer_full_scan = 1; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET @@session.optimizer_full_scan = -1; | ||
| ERROR 42000: Variable 'optimizer_full_scan' can't be set to the value of '-1' | ||
| SET @@session.optimizer_full_scan = 2; | ||
| ERROR 42000: Variable 'optimizer_full_scan' can't be set to the value of '2' | ||
| SET @@session.optimizer_full_scan = "T"; | ||
| ERROR 42000: Variable 'optimizer_full_scan' can't be set to the value of 'T' | ||
| SET @@session.optimizer_full_scan = "Y"; | ||
| ERROR 42000: Variable 'optimizer_full_scan' can't be set to the value of 'Y' | ||
| SET @@session.optimizer_full_scan = NO; | ||
| ERROR 42000: Variable 'optimizer_full_scan' can't be set to the value of 'NO' | ||
| SET @@global.optimizer_full_scan = 1; | ||
| SELECT @@global.optimizer_full_scan; | ||
| @@global.optimizer_full_scan | ||
| 1 | ||
| SET @@global.optimizer_full_scan = 0; | ||
| SELECT count(VARIABLE_VALUE) FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
| count(VARIABLE_VALUE) | ||
| 1 | ||
| SELECT IF(@@session.optimizer_full_scan, "ON", "OFF") = VARIABLE_VALUE | ||
| FROM INFORMATION_SCHEMA.SESSION_VARIABLES | ||
| WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
| IF(@@session.optimizer_full_scan, "ON", "OFF") = VARIABLE_VALUE | ||
| 1 | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SELECT VARIABLE_VALUE | ||
| FROM INFORMATION_SCHEMA.SESSION_VARIABLES | ||
| WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
| VARIABLE_VALUE | ||
| ON | ||
| SET @@session.optimizer_full_scan = OFF; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 0 | ||
| SET @@session.optimizer_full_scan = ON; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET @@session.optimizer_full_scan = TRUE; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET @@session.optimizer_full_scan = FALSE; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 0 | ||
| SET @@session.optimizer_full_scan = @session_start_value; | ||
| SELECT @@session.optimizer_full_scan; | ||
| @@session.optimizer_full_scan | ||
| 1 | ||
| SET @@global.optimizer_full_scan = @global_start_value; | ||
| SELECT @@global.optimizer_full_scan; | ||
| @@global.optimizer_full_scan | ||
| 1 |
102 changes: 102 additions & 0 deletions
102
mysql-test/suite/sys_vars/t/optimizer_full_scan_basic.test
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,102 @@ | ||
| --source include/load_sysvars.inc | ||
|
|
||
|
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||
| # Saving initial value of optimizer_full_scan in a temporary variable | ||
|
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||
| SET @session_start_value = @@session.optimizer_full_scan; | ||
| SELECT @session_start_value; | ||
| SET @global_start_value = @@global.optimizer_full_scan; | ||
| SELECT @global_start_value; | ||
|
|
||
| # Display the DEFAULT value of optimizer_full_scan | ||
|
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||
| SET @@session.optimizer_full_scan = 0; | ||
| SET @@session.optimizer_full_scan = DEFAULT; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
|
||
| SET @@session.optimizer_full_scan = 1; | ||
| SET @@session.optimizer_full_scan = DEFAULT; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
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||
|
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| # Check if optimizer_full_scan can be accessed with and without @@ sign | ||
|
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| SET optimizer_full_scan = 1; | ||
| SELECT @@optimizer_full_scan; | ||
|
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||
| --Error ER_UNKNOWN_TABLE | ||
| SELECT session.optimizer_full_scan; | ||
|
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||
| --Error ER_UNKNOWN_TABLE | ||
| SELECT local.optimizer_full_scan; | ||
|
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| SET session optimizer_full_scan = 0; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
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||
| # change the value of optimizer_full_scan to a valid value | ||
|
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| SET @@session.optimizer_full_scan = 0; | ||
| SELECT @@session.optimizer_full_scan; | ||
| SET @@session.optimizer_full_scan = 1; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
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||
|
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| # Change the value of optimizer_full_scan to invalid value | ||
|
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| --Error ER_WRONG_VALUE_FOR_VAR | ||
| SET @@session.optimizer_full_scan = -1; | ||
| --Error ER_WRONG_VALUE_FOR_VAR | ||
| SET @@session.optimizer_full_scan = 2; | ||
| --Error ER_WRONG_VALUE_FOR_VAR | ||
| SET @@session.optimizer_full_scan = "T"; | ||
| --Error ER_WRONG_VALUE_FOR_VAR | ||
| SET @@session.optimizer_full_scan = "Y"; | ||
| --Error ER_WRONG_VALUE_FOR_VAR | ||
| SET @@session.optimizer_full_scan = NO; | ||
|
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||
|
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| # Test if accessing global optimizer_full_scan gives error | ||
|
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| SET @@global.optimizer_full_scan = 1; | ||
| SELECT @@global.optimizer_full_scan; | ||
| SET @@global.optimizer_full_scan = 0; | ||
|
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|
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| # Check if the value in GLOBAL Table contains variable value | ||
|
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| SELECT count(VARIABLE_VALUE) FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
|
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| # Check if the value in GLOBAL Table matches value in variable | ||
|
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| SELECT IF(@@session.optimizer_full_scan, "ON", "OFF") = VARIABLE_VALUE | ||
| FROM INFORMATION_SCHEMA.SESSION_VARIABLES | ||
| WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
| SELECT @@session.optimizer_full_scan; | ||
| SELECT VARIABLE_VALUE | ||
| FROM INFORMATION_SCHEMA.SESSION_VARIABLES | ||
| WHERE VARIABLE_NAME='optimizer_full_scan'; | ||
|
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| # Check if ON and OFF values can be used on variable | ||
|
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| SET @@session.optimizer_full_scan = OFF; | ||
| SELECT @@session.optimizer_full_scan; | ||
| SET @@session.optimizer_full_scan = ON; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
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| # Check if TRUE and FALSE values can be used on variable | ||
|
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| SET @@session.optimizer_full_scan = TRUE; | ||
| SELECT @@session.optimizer_full_scan; | ||
| SET @@session.optimizer_full_scan = FALSE; | ||
| SELECT @@session.optimizer_full_scan; | ||
|
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| # Restore initial value | ||
|
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| SET @@session.optimizer_full_scan = @session_start_value; | ||
| SELECT @@session.optimizer_full_scan; | ||
| SET @@global.optimizer_full_scan = @global_start_value; | ||
| SELECT @@global.optimizer_full_scan; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,65 @@ | ||
| set @orig_optimizer_full_scan = @@optimizer_full_scan; | ||
| set @orig_optimizer_force_index_for_range = @@optimizer_force_index_for_range; | ||
|
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||
| create table t (i int, j int, key(i)); | ||
| insert into t values (1, 1); | ||
| insert into t values (1, 2); | ||
| insert into t values (2, 1); | ||
| insert into t values (2, 2); | ||
| insert into t values (3, 1); | ||
| insert into t values (3, 2); | ||
|
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| analyze table t; | ||
|
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| --echo # Basic tests | ||
| --replace_column 9 # | ||
| explain select * from t; | ||
| set optimizer_full_scan = off; | ||
| --error ER_FULL_SCAN_DISABLED | ||
| select * from t; | ||
| set optimizer_full_scan = on; | ||
| select * from t; | ||
|
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| --replace_column 9 # | ||
| explain select * from t force index (i); | ||
| set optimizer_full_scan = off; | ||
| --error ER_FULL_SCAN_DISABLED | ||
| select i from t force index (i); | ||
| set optimizer_full_scan = on; | ||
| select i from t force index (i); | ||
|
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||
| --replace_column 9 # | ||
| explain select * from t a, t b where a.i = b.i; | ||
| set optimizer_full_scan = off; | ||
| --error ER_FULL_SCAN_DISABLED | ||
| select * from t a, t b where a.i = b.i; | ||
| set optimizer_full_scan = on; | ||
| select * from t a, t b where a.i = b.i; | ||
|
|
||
| --replace_column 9 # | ||
| explain select * from t a straight_join t b where a.i = 10; | ||
| set optimizer_full_scan = off; | ||
| --error ER_FULL_SCAN_DISABLED | ||
| select * from t a straight_join t b where a.i = 10; | ||
| set optimizer_full_scan = on; | ||
| select * from t a straight_join t b where a.i = 10; | ||
|
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| --echo # Test integration with optimizer_force_index_for_range | ||
| alter table t drop index i, add primary key (i, j); | ||
|
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| --echo # Test range plans | ||
| set optimizer_force_index_for_range = on; | ||
| set optimizer_full_scan = off; | ||
| --replace_column 9 # | ||
| explain select i from t where i in (1, 2, 3) and j in (1, 2); | ||
| --error ER_FULL_SCAN_DISABLED | ||
| select i from t where i in (1, 2, 3) and j in (1, 2); | ||
| --replace_column 9 # | ||
| explain select i from t force index (primary) where i in (1, 2, 3) and j in (1, 2); | ||
| select i from t force index (primary) where i in (1, 2, 3) and j in (1, 2); | ||
|
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| drop table t; | ||
|
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| set optimizer_full_scan = @orig_optimizer_full_scan; | ||
| set optimizer_force_index_for_range = @orig_optimizer_force_index_for_range; | ||
|
|
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