Description:
Running the command "mysqld --help --verbose" gives a list of all
configuration variables with default values. One of these
configuration variables is "optimizer_switch". In some cases the list
of valied flags this can take gets "truncated". It seems like if the
following conditions is ful-filled then the optimzier_switch flag is
not written:
1. The value of the optimizer_switch flag is off
2. It is either the last on the list of optimzer_switch flags or all
flags listed after it is off
To illustrate this:
1. Run mysqld --help --verbose without changing any default values:
./sql/mysqld --no-defaults --help --verbose
This lists in the help output for "optimizer-switch":
index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
This is correct (good)
2. Disable two of these switches (one "in the middle" and the last one):
./sql/mysqld --no-defaults --optimizer-switch="index_merge_sort_union=off,engine_condition_pushdown=off" --help --verbose
This lists in the output for "optimizer-switch":
index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on
This does not look correct:
-the index_merge_sort_union flag is listed as off (good)
-the engine_condtion_pushdown flag is not lasted (bad)
This is inconsistent treatment of the flags with value off (bad).
3. Disable multiple switches on the end of the list:
./sql/mysqld --no-defaults --optimizer-switch="index_merge_sort_union=off,index_merge_intersection=off,engine_condition_pushdown=off" --help --verbose
This lists in the output for "optimizer-switch":
index_merge=on,index_merge_union=on
This does not look correct:
-none of the flags with value off gets listed (bad)
How to repeat:
See above.
Suggested fix:
All optimizer_switch flags should get written when running mysqld --help --verbose.
Description: Running the command "mysqld --help --verbose" gives a list of all configuration variables with default values. One of these configuration variables is "optimizer_switch". In some cases the list of valied flags this can take gets "truncated". It seems like if the following conditions is ful-filled then the optimzier_switch flag is not written: 1. The value of the optimizer_switch flag is off 2. It is either the last on the list of optimzer_switch flags or all flags listed after it is off To illustrate this: 1. Run mysqld --help --verbose without changing any default values: ./sql/mysqld --no-defaults --help --verbose This lists in the help output for "optimizer-switch": index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on This is correct (good) 2. Disable two of these switches (one "in the middle" and the last one): ./sql/mysqld --no-defaults --optimizer-switch="index_merge_sort_union=off,engine_condition_pushdown=off" --help --verbose This lists in the output for "optimizer-switch": index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on This does not look correct: -the index_merge_sort_union flag is listed as off (good) -the engine_condtion_pushdown flag is not lasted (bad) This is inconsistent treatment of the flags with value off (bad). 3. Disable multiple switches on the end of the list: ./sql/mysqld --no-defaults --optimizer-switch="index_merge_sort_union=off,index_merge_intersection=off,engine_condition_pushdown=off" --help --verbose This lists in the output for "optimizer-switch": index_merge=on,index_merge_union=on This does not look correct: -none of the flags with value off gets listed (bad) How to repeat: See above. Suggested fix: All optimizer_switch flags should get written when running mysqld --help --verbose.