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| author | Varun Gupta <varun.gupta@mariadb.com> | 2019-02-13 11:22:16 +0530 |
|---|---|---|
| committer | Varun Gupta <varun.gupta@mariadb.com> | 2019-02-13 11:52:36 +0530 |
| commit | be8709eb7bdf2a68a1c04fd8ab368113f5f39b63 (patch) | |
| tree | 35585804a654ec75089a92e90d546f73e7f60b68 /mysql-test/main/mysqld--help.result | |
| parent | 6b979416e0e4eac0a036ca5f2b81b748a3d2e680 (diff) | |
| download | mariadb-git-be8709eb7bdf2a68a1c04fd8ab368113f5f39b63.tar.gz | |
MDEV-6111 Optimizer Trace
This task involves the implementation for the optimizer trace.
This feature produces a trace for any SELECT/UPDATE/DELETE/,
which contains information about decisions taken by the optimizer during
the optimization phase (choice of table access method, various costs,
transformations, etc). This feature would help to tell why some decisions were
taken by the optimizer and why some were rejected.
Trace is session-local, controlled by the @@optimizer_trace variable.
To enable optimizer trace we need to write:
set @@optimizer_trace variable= 'enabled=on';
To display the trace one can run:
SELECT trace FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
This task also involves:
MDEV-18489: Limit the memory used by the optimizer trace
introduces a switch optimizer_trace_max_mem_size which limits
the memory used by the optimizer trace. This was implemented by
Sergei Petrunia.
Diffstat (limited to 'mysql-test/main/mysqld--help.result')
| -rw-r--r-- | mysql-test/main/mysqld--help.result | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/mysql-test/main/mysqld--help.result b/mysql-test/main/mysqld--help.result index d621c5c8cae..47ebfa7a8ab 100644 --- a/mysql-test/main/mysqld--help.result +++ b/mysql-test/main/mysqld--help.result @@ -693,6 +693,12 @@ The following specify which files/extra groups are read (specified before remain extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived, split_materialized, condition_pushdown_for_subquery + --optimizer-trace=name + Controls tracing of the Optimizer: + optimizer_trace=option=val[,option=val...], where option + is one of {enabled} and val is one of {on, off, default} + --optimizer-trace-max-mem-size=# + Maximum allowed size of an optimizer trace --optimizer-use-condition-selectivity=# Controls selectivity of which conditions the optimizer takes into account to calculate cardinality of a partial @@ -1563,6 +1569,8 @@ optimizer-prune-level 1 optimizer-search-depth 62 optimizer-selectivity-sampling-limit 100 optimizer-switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on,condition_pushdown_for_subquery=on +optimizer-trace +optimizer-trace-max-mem-size 1048576 optimizer-use-condition-selectivity 4 performance-schema FALSE performance-schema-accounts-size -1 |