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Optimizer trace: print cost and #rows of the join prefix

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The names rows_for_plan and cost_for_plan follow MySQL
Also added post-join-operation selectivity cost
This commit is contained in:
Sergei Petrunia
2019-08-10 00:53:28 +03:00
parent 95cdc1ca5f
commit 2dbe472ed0
6 changed files with 502 additions and 37 deletions
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487
mysql-test/main/opt_trace.result
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File diff suppressed because it is too large Load Diff

27
mysql-test/main/opt_trace.test
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@ -508,4 +508,31 @@ SET optimizer_trace = 'enabled=on';
DELETE FROM t1 WHERE f = 'x';
DROP TABLE t1;
--echo #
--echo # Print cost_for_plan and rows_for_plan for join prefix
--echo #
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table one_k (a int, b int, key(b));
insert into one_k select A.a + B.a*10 + C.a*100, A.a + B.a*10 + C.a*100 from t0 A, t0 B, t0 C;
analyze table t0, one_k persistent for all;
set @tmp_jcl=@@join_cache_level;
set join_cache_level=0;
set optimizer_trace=1;
--echo # Check cost/row numbers when multiple tables are joined
--echo # (cost_for_plan is the same as best_access_path.cost for single-table SELECTs
--echo # but for joins using condition selectivity it is not as trivial. So,
--echo # now we are printing it)
explain select * from t0 A, one_k B where A.a<5 and B.a<800;
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.considered_execution_plans')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
set join_cache_level=@tmp_jcl;
--echo # This shows post-join selectivity
explain select * from t0 A, one_k B where A.a=B.b and B.a<800;
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.considered_execution_plans')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
set optimizer_trace='enabled=off';

4
mysql-test/main/opt_trace_index_merge.result
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@ -213,7 +213,9 @@ explain select * from t1 where a=1 or b=1 {
"chosen": true
}
]
}
},
"rows_for_plan": 2,
"cost_for_plan": 4.5484
}
]
},

4
mysql-test/main/opt_trace_index_merge_innodb.result
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@ -209,7 +209,9 @@ explain select * from t1 where pk1 != 0 and key1 = 1 {
"cause": "cost"
}
]
}
},
"rows_for_plan": 1,
"cost_for_plan": 2.2
}
]
},

8
mysql-test/main/opt_trace_security.result
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@ -99,7 +99,9 @@ select * from db1.t1 {
"chosen": true
}
]
}
},
"rows_for_plan": 3,
"cost_for_plan": 2.6051
}
]
},
@ -210,7 +212,9 @@ select * from db1.v1 {
"chosen": true
}
]
}
},
"rows_for_plan": 3,
"cost_for_plan": 2.6051
}
]
},

9
sql/sql_select.cc
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@ -9383,6 +9383,11 @@ best_extension_by_limited_search(JOIN *join,
current_record_count /
(double) TIME_FOR_COMPARE));
if (unlikely(thd->trace_started()))
{
trace_one_table.add("rows_for_plan", current_record_count);
trace_one_table.add("cost_for_plan", current_read_time);
}
advance_sj_state(join, remaining_tables, idx, &current_record_count,
&current_read_time, &loose_scan_pos);
@ -9441,6 +9446,10 @@ best_extension_by_limited_search(JOIN *join,
remaining_tables &
~real_table_bit);
join->positions[idx].cond_selectivity= pushdown_cond_selectivity;
if (unlikely(thd->trace_started()) && pushdown_cond_selectivity < 1.0)
trace_one_table.add("selectivity", pushdown_cond_selectivity);
double partial_join_cardinality= current_record_count *
pushdown_cond_selectivity;
if ( (search_depth > 1) && (remaining_tables & ~real_table_bit) & allowed_tables )