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c17468d4ab
subquery when ORDER BY is present Currently for setting r_limit we divide with the number of iterations we invoke the dependent subquery. This is not needed for the case of limit. For varying limits we produce the output that the limit varies with execution. Also there is a type for filtered , we forgot to multiply by 100 as it is represented as a percent.
587 lines
14 KiB
Plaintext
587 lines
14 KiB
Plaintext
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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create table t1(a int);
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insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
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create table t2 (
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a int,
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b int,
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key (a)
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);
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insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
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#
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# Try an UPDATE that uses filesort:
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#
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explain
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update t2 set b=b+1 order by b limit 5;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 ALL NULL NULL NULL NULL 10000 Using filesort
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explain format=json
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update t2 set b=b+1 order by b limit 5;
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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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"filesort": {
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"table": {
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"update": 1,
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"table_name": "t2",
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"access_type": "ALL",
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"rows": 10000
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}
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}
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}
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}
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analyze format=json
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update t2 set b=b+1 order by b limit 5;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_total_time_ms": "REPLACED",
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_limit": 5,
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"r_used_priority_queue": true,
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"r_output_rows": 6,
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"table": {
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"update": 1,
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"table_name": "t2",
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"access_type": "ALL",
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"rows": 10000,
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"r_rows": 10000,
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"r_filtered": 100,
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"r_total_time_ms": "REPLACED"
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}
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}
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}
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}
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#
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# Try an UPDATE that uses buffering:
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#
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explain
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update t2 set a=a+1 where a<10;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 range a a 5 NULL 8 Using where; Using buffer
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explain format=json
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update t2 set a=a+1 where a<10;
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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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"buffer": {
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"table": {
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"update": 1,
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"table_name": "t2",
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"access_type": "range",
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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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"rows": 8,
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"attached_condition": "(t2.a < 10)"
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}
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}
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}
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}
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analyze format=json
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update t2 set a=a+1 where a<10;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_total_time_ms": "REPLACED",
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"buffer": {
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"table": {
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"update": 1,
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"table_name": "t2",
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"access_type": "range",
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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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"rows": 8,
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"r_rows": 10,
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"r_filtered": 100,
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"r_total_time_ms": "REPLACED",
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"attached_condition": "(t2.a < 10)"
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}
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}
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}
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}
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#
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# Try a DELETE that uses filesort:
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#
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explain
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delete from t2 order by b limit 5;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 ALL NULL NULL NULL NULL 10000 Using filesort
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explain format=json
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delete from t2 order by b limit 5;
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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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"filesort": {
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"table": {
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"delete": 1,
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"table_name": "t2",
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"access_type": "ALL",
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"rows": 10000
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}
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}
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}
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}
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analyze format=json
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delete from t2 order by b limit 5;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_total_time_ms": "REPLACED",
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_used_priority_queue": false,
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"r_output_rows": 10000,
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"r_buffer_size": "REPLACED",
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"table": {
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"delete": 1,
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"table_name": "t2",
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"access_type": "ALL",
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"rows": 10000,
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"r_rows": 10000,
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"r_filtered": 100,
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"r_total_time_ms": "REPLACED"
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}
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}
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}
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}
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#
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# Try a SELECT with QEP in form: filesort { tmp_table { join } }
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#
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explain
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select * from t0,t2 where t2.a=t0.a order by t2.b limit 4;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where; Using temporary; Using filesort
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1 SIMPLE t2 ref a a 5 test.t0.a 1
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explain format=json
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select * from t0,t2 where t2.a=t0.a order by t2.b limit 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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"filesort": {
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"temporary_table": {
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"function": "buffer",
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"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": "t2",
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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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"rows": 1,
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"filtered": 100
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}
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}
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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 t0,t2 where t2.a=t0.a order by t2.b limit 4;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_limit": 4,
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"r_used_priority_queue": true,
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"r_output_rows": 4,
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"temporary_table": {
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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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"r_total_time_ms": "REPLACED",
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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": "t2",
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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": 0.4,
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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 100
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}
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}
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}
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}
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}
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#
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# Try a SELECT with QEP in form: join { filesort { table0 }, table2 }
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#
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explain
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select * from t0,t2 where t2.a=t0.a order by t0.a limit 4;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where; Using filesort
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1 SIMPLE t2 ref a a 5 test.t0.a 1
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explain format=json
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select * from t0,t2 where t2.a=t0.a order by t0.a limit 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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"read_sorted_file": {
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"filesort": {
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"table": {
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"table_name": "t0",
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"access_type": "ALL",
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"rows": 10,
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"filtered": 100,
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"attached_condition": "(t0.a is not null)"
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}
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}
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},
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"table": {
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"table_name": "t2",
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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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"rows": 1,
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"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 t0,t2 where t2.a=t0.a order by t0.a limit 4;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"read_sorted_file": {
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"r_rows": 10,
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_used_priority_queue": false,
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"r_output_rows": 10,
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"r_buffer_size": "REPLACED",
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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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"r_total_time_ms": "REPLACED",
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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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}
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},
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"table": {
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"table_name": "t2",
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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": 0.4,
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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 100
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}
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}
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}
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drop table t2;
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create table t2 (
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a int,
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b int,
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c int
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);
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insert into t2
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select
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a.a+10*b.a+100*c.a,
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b.a+10*c.a,
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c.a
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from t0 a, t0 b, t0 c;
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analyze format=json
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select MAX(b) from t2 where mod(a,2)=0 group by c;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_used_priority_queue": false,
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"r_output_rows": 10,
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"r_buffer_size": "REPLACED",
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"temporary_table": {
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"table": {
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"table_name": "t2",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 1000,
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"r_rows": 1000,
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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 50,
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"attached_condition": "((t2.a % 2) = 0)"
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}
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}
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}
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}
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}
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drop table t2;
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#
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# MDEV-8282: crash in filesort() with simple ordered delete
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#
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create table t3(a int) engine=innodb;
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delete from t3 order by a;
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# EXPLAIN thinks it will use delete_all_rows():
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explain
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delete from t3 order by a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL 1 Deleting all rows
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# ANALYZE shows that delete_all_rows() didn't work and we deleted rows
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# one-by-one:
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analyze
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delete from t3 order by a;
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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 t3 ALL NULL NULL NULL NULL 1 0.00 100.00 100.00 Using filesort
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drop table t3;
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#
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# A test for duplicate_removal()
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#
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create table t3 (a int, b int);
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insert into t3 select a, 123 from t0;
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analyze format=json
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select distinct max(t3.b) Q from t0, t3 where t0.a=t3.a group by t0.a order by null;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"duplicate_removal": {
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"temporary_table": {
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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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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 100
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},
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"block-nl-join": {
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"table": {
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"table_name": "t3",
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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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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 100
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},
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"buffer_type": "flat",
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"buffer_size": "256Kb",
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"join_type": "BNL",
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"attached_condition": "(t3.a = t0.a)",
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"r_filtered": 10
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}
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}
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}
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}
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}
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#
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# A query with two filesort calls:
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# - first is needed to do group-by-group grouping to calculate COUNT(DISTINCT)
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# - the second is need to produce ORDER BY.
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# (see MDEV-7836 for description of the query plan)
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create table t5 (a int , b int) ;
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create table t6 like t5 ;
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create table t7 like t5 ;
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insert into t5 values (0, 100), (1, 2), (1, 3), (2, 2), (2, 7),
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(2, -1), (3, 10);
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insert into t6 values (0, 0), (1, 1), (2, 1), (3, 1), (4, 1);
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insert into t7 values (3, 3), (2, 2), (1, 1);
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# TODO: This ANALYZE output doesn't make it clear what is used for what.
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analyze format=json
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select count(distinct t5.b) as sum from t5, t6
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where t5.a=t6.a and t6.b > 0 and t5.a <= 5
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group by t5.a order by sum limit 1;
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ANALYZE
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{
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"query_block": {
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"select_id": 1,
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_limit": 1,
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"r_used_priority_queue": true,
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"r_output_rows": 2,
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"filesort": {
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"r_loops": 1,
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"r_total_time_ms": "REPLACED",
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"r_used_priority_queue": false,
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"r_output_rows": 6,
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"r_buffer_size": "REPLACED",
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"temporary_table": {
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"temporary_table": {
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"table": {
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"table_name": "t6",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 5,
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"r_rows": 5,
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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 80,
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"attached_condition": "((t6.b > 0) and (t6.a <= 5))"
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},
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"block-nl-join": {
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"table": {
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"table_name": "t5",
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"access_type": "ALL",
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"r_loops": 1,
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"rows": 7,
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"r_rows": 7,
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"r_total_time_ms": "REPLACED",
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"filtered": 100,
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"r_filtered": 100
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},
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"buffer_type": "flat",
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"buffer_size": "256Kb",
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"join_type": "BNL",
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"attached_condition": "(t5.a = t6.a)",
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"r_filtered": 21.429
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}
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}
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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 count(distinct t5.b) as sum from t5, t6
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where t5.a=t6.a and t6.b > 0 and t5.a <= 5
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group by t5.a order by sum limit 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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"filesort": {
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"temporary_table": {
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"function": "buffer",
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"table": {
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"table_name": "t6",
|
|
"access_type": "ALL",
|
|
"rows": 5,
|
|
"filtered": 100,
|
|
"attached_condition": "((t6.b > 0) and (t6.a <= 5))"
|
|
},
|
|
"block-nl-join": {
|
|
"table": {
|
|
"table_name": "t5",
|
|
"access_type": "ALL",
|
|
"rows": 7,
|
|
"filtered": 100
|
|
},
|
|
"buffer_type": "flat",
|
|
"buffer_size": "256Kb",
|
|
"join_type": "BNL",
|
|
"attached_condition": "(t5.a = t6.a)"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
drop table t5,t6,t7;
|
|
drop table t3;
|
|
#
|
|
# Tabular ANALYZE must get its data from execution tracker (and not from
|
|
# the query plan)
|
|
#
|
|
CREATE TABLE t2(
|
|
col1 int,
|
|
col2 int,
|
|
UNIQUE INDEX idx (col1, col2)) engine=myisam;
|
|
INSERT INTO t2(col1, col2) VALUES
|
|
(1,20),(2,19),(3,18),(4,17),(5,16),(6,15),(7,14),(8,13),(9,12),(10,11),
|
|
(11,10),(12,9),(13,8),(14,7),(15,6),(16,5),(17,4),(18,3),(19,2),(20,1);
|
|
flush status;
|
|
explain
|
|
select col1 f1, col2 f2, col1 f3 from t2 group by f1;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t2 range NULL idx 5 NULL 7 Using index for group-by
|
|
analyze
|
|
select col1 f1, col2 f2, col1 f3 from t2 group by f1;
|
|
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
|
|
1 SIMPLE t2 range NULL idx 5 NULL 7 20.00 100.00 100.00 Using index for group-by
|
|
analyze format=json
|
|
select col1 f1, col2 f2, col1 f3 from t2 group by f1;
|
|
ANALYZE
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"r_loops": 1,
|
|
"r_total_time_ms": "REPLACED",
|
|
"table": {
|
|
"table_name": "t2",
|
|
"access_type": "range",
|
|
"key": "idx",
|
|
"key_length": "5",
|
|
"used_key_parts": ["col1"],
|
|
"r_loops": 1,
|
|
"rows": 7,
|
|
"r_rows": 20,
|
|
"r_total_time_ms": "REPLACED",
|
|
"filtered": 100,
|
|
"r_filtered": 100,
|
|
"using_index_for_group_by": true
|
|
}
|
|
}
|
|
}
|
|
drop table t2;
|
|
drop table t0,t1;
|