diff options
Diffstat (limited to 'sql/sys_vars.cc')
| -rw-r--r-- | sql/sys_vars.cc | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc index 7f6a00f3c62..2bf9a55f8b1 100644 --- a/sql/sys_vars.cc +++ b/sql/sys_vars.cc @@ -1431,14 +1431,17 @@ static Sys_var_ulong Sys_optimizer_use_condition_selectivity( "for the best execution plan " "Meaning: " "1 - use selectivity of index backed range conditions to calculate " - "cardinality of the partial join if the last joined table is " - "accessed by full table scan or an index scan " + "the cardinality of a partial join if the last joined table is " + "accessed by full table scan or an index scan, " "2 - use selectivity of index backed range conditions to calculate " - "cardinality of the partial join in any case " + "the cardinality of a partial join in any case, " "3 - additionally always use selectivity of range conditions that are " - "not backed by any index to calculate cardinality of the partial join", + "not backed by any index to calculate the cardinality of a partial join, " + "4 - use histograms to calculate selectivity of range conditions that " + "are not backed by any index to calculate the cardinality of " + "a partial join.", SESSION_VAR(optimizer_use_condition_selectivity), CMD_LINE(REQUIRED_ARG), - VALID_RANGE(1, 3), DEFAULT(1), BLOCK_SIZE(1)); + VALID_RANGE(1, 4), DEFAULT(1), BLOCK_SIZE(1)); /** Warns about deprecated value 63 */ static bool fix_optimizer_search_depth(sys_var *self, THD *thd, @@ -3767,6 +3770,13 @@ static Sys_var_enum Sys_optimizer_use_stat_tables( SESSION_VAR(use_stat_tables), CMD_LINE(REQUIRED_ARG), use_stat_tables_modes, DEFAULT(0)); +static Sys_var_ulong Sys_histogram_size( + "histogram_size", + "Number of bytes used for a histogram. " + "If set to 0, no histograms are created by ANALYZE.", + SESSION_VAR(histogram_size), CMD_LINE(REQUIRED_ARG), + VALID_RANGE(0, 255), DEFAULT(0), BLOCK_SIZE(1)); + static Sys_var_mybool Sys_no_thread_alarm( "debug_no_thread_alarm", "Disable system thread alarm calls. Disabling it may be useful " |