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105 lines
2.3 KiB
Text
105 lines
2.3 KiB
Text
create table t1 (a int, b int);
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insert into t1 values (1,1),(2,2);
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explain format=json
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select * from t1 where a=name_const('varname',1);
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"cost": "COST_REPLACED",
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"nested_loop": [
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{
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"table": {
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"table_name": "t1",
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"access_type": "ALL",
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"loops": 1,
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"rows": 2,
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"cost": "COST_REPLACED",
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"filtered": 100,
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"attached_condition": "t1.a = 1"
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}
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}
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]
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}
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}
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explain format=json
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select * from t1 left join t1 as t2 on t1.a=name_const('varname',1) and t1.b=t2.b;
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"cost": "COST_REPLACED",
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"const_condition": "1",
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"nested_loop": [
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{
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"table": {
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"table_name": "t1",
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"access_type": "ALL",
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"loops": 1,
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"rows": 2,
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"cost": "COST_REPLACED",
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"filtered": 100
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}
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},
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{
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"block-nl-join": {
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"table": {
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"table_name": "t2",
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"access_type": "ALL",
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"loops": 2,
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"rows": 2,
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"cost": "COST_REPLACED",
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"filtered": 100
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},
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"buffer_type": "flat",
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"buffer_size": "141",
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"join_type": "BNL",
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"attached_condition": "trigcond(t2.b = t1.b and trigcond(t1.a = 1))"
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}
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}
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]
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}
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}
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create table t2 (
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a varchar(100) collate utf8_unicode_ci,
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b int
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);
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insert into t2 values ('foo', 1),('bar', 1);
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create procedure p1(var1 varchar(10))
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update t2 set b=b+1 where a=var1;
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call p1('foo');
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call p1('foo');
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call p1('foo');
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select * from t2;
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a b
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foo 4
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bar 1
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create table t3 (
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a varchar(100) collate utf8_unicode_ci,
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b int
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);
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insert into t3 values ('foo', 1),('bar', 1);
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select * from t3;
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a b
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foo 1
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bar 1
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explain format=json
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update t3 set b=b+1 where a= NAME_CONST('var1',_latin1'foo' COLLATE 'latin1_swedish_ci');
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EXPLAIN
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{
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"query_block": {
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"select_id": 1,
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"table": {
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"update": 1,
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"table_name": "t3",
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"access_type": "ALL",
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"rows": 2,
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"attached_condition": "t3.a = convert(_latin1'foo' collate latin1_swedish_ci using utf8mb3)"
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}
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}
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}
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select * from t3 where a= NAME_CONST('var1',_latin1'foo' COLLATE 'latin1_swedish_ci');
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a b
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foo 1
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drop procedure p1;
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drop table t1, t2, t3;
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