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658128af43
This patch contains a full implementation of the optimization
that allows to use in-memory rowid / primary filters built for range
conditions over indexes. In many cases usage of such filters reduce
the number of disk seeks spent for fetching table rows.
In this implementation the choice of what possible filter to be applied
(if any) is made purely on cost-based considerations.
This implementation re-achitectured the partial implementation of
the feature pushed by Galina Shalygina in the commit
8d5a11122c.
Besides this patch contains a better implementation of the generic
handler function handler::multi_range_read_info_const() that
takes into account gaps between ranges when calculating the cost of
range index scans. It also contains some corrections of the
implementation of the handler function records_in_range() for MyISAM.
This patch supports the feature for InnoDB and MyISAM.
597 lines
15 KiB
Text
597 lines
15 KiB
Text
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 9 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": 9,
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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": 9,
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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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"sort_key": "t2.b",
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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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"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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"sort_key": "t2.b",
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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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"sort_key": "t0.a",
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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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"sort_key": "t0.a",
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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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"sort_key": "t2.c",
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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 MOD 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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"sort_key": "count(distinct t5.b)",
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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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"temporary_table": {
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"filesort": {
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"sort_key": "t5.a",
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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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"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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}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
explain format=json
|
|
select count(distinct t5.b) as sum from t5, t6
|
|
where t5.a=t6.a and t6.b > 0 and t5.a <= 5
|
|
group by t5.a order by sum limit 1;
|
|
EXPLAIN
|
|
{
|
|
"query_block": {
|
|
"select_id": 1,
|
|
"filesort": {
|
|
"sort_key": "count(distinct t5.b)",
|
|
"temporary_table": {
|
|
"filesort": {
|
|
"sort_key": "t5.a",
|
|
"temporary_table": {
|
|
"table": {
|
|
"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;
|