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753718c201
- Switch Explain data structure from "flat" representation of SJ-Materialization into nested one. - Update functions that print tabular output to operate on the nested structure. - Add function to generate JSON output.
171 lines
4.2 KiB
Text
171 lines
4.2 KiB
Text
drop table if exists t0,t1,t2,t3;
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create table t0 (a int);
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INSERT INTO t0 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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# r_filtered=30%, because 3 rows match: 0,1,2
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analyze format=json select * from t0 where a<3;
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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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"table_name": "t0",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 10,
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"r_rows": 10,
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"filtered": 100,
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"r_filtered": 30,
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"attached_condition": "(t0.a < 3)"
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}
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}
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}
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create table t1 (a int, b int, c int, key(a));
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insert into t1 select A.a*10 + B.a, A.a*10 + B.a, A.a*10 + B.a from t0 A, t0 B;
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analyze
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select * from t0, t1 where t1.a=t0.a and t0.a > 9;
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id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 10 10 100.00 0.00 Using where
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1 SIMPLE t1 ref a a 5 test.t0.a 1 NULL 100.00 NULL
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analyze format=json
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select * from t0, t1 where t1.a=t0.a and t0.a > 9;
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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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"table_name": "t0",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 10,
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"r_rows": 10,
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"filtered": 100,
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"r_filtered": 0,
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"attached_condition": "((t0.a > 9) and (t0.a is not null))"
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},
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"table": {
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"table_name": "t1",
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"access_type": "ref",
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"possible_keys": ["a"],
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"key": "a",
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"key_length": "5",
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"used_key_parts": ["a"],
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"ref": ["test.t0.a"],
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"r_loops": 0,
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"rows": 1,
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"r_rows": null,
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"filtered": 100,
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"r_filtered": null
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}
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}
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}
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analyze
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select * from t0, t1 where t1.a=t0.a and t1.b<4;
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id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 10 10 100.00 100.00 Using where
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1 SIMPLE t1 ref a a 5 test.t0.a 1 1 100.00 40.00 Using where
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analyze format=json
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select * from t0, t1 where t1.a=t0.a and t1.b<4;
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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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"table_name": "t0",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 10,
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"r_rows": 10,
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"filtered": 100,
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"r_filtered": 100,
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"attached_condition": "(t0.a is not null)"
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},
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"table": {
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"table_name": "t1",
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"access_type": "ref",
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"possible_keys": ["a"],
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"key": "a",
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"key_length": "5",
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"used_key_parts": ["a"],
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"ref": ["test.t0.a"],
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"r_loops": 10,
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"rows": 1,
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"r_rows": 1,
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"filtered": 100,
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"r_filtered": 40,
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"attached_condition": "(t1.b < 4)"
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}
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}
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}
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analyze
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select * from t1 A, t1 B where A.b<2 and B.b>5;
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id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
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1 SIMPLE A ALL NULL NULL NULL NULL 100 100 100.00 2.00 Using where
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1 SIMPLE B ALL NULL NULL NULL NULL 100 100 100.00 94.00 Using where; Using join buffer (flat, BNL join)
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analyze format=json
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select * from t1 A, t1 B where A.b<20 and B.b<60;
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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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"table_name": "A",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 100,
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"r_rows": 100,
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"filtered": 100,
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"r_filtered": 20,
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"attached_condition": "(A.b < 20)"
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},
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"block-nl-join": {
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"table": {
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"table_name": "B",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 100,
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"r_rows": 100,
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"filtered": 100,
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"r_filtered": 60
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},
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"buffer_type": "flat",
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"join_type": "BNL",
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"r_filtered": 100
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}
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}
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}
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analyze format=json
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select * from t1 A, t1 B where A.b<20 and B.b<60 and A.c > B.c;
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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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"table_name": "A",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 100,
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"r_rows": 100,
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"filtered": 100,
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"r_filtered": 20,
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"attached_condition": "(A.b < 20)"
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},
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"block-nl-join": {
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"table": {
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"table_name": "B",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 100,
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"r_rows": 100,
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"filtered": 100,
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"r_filtered": 60,
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"attached_condition": "(B.b < 60)"
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},
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"buffer_type": "flat",
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"join_type": "BNL",
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"attached_condition": "(A.c > B.c)",
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"r_filtered": 15.833
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}
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}
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}
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drop table t1;
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drop table t0;
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