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| author | Sergei Petrunia <psergey@askmonty.org> | 2021-01-28 21:43:55 +0300 |
|---|---|---|
| committer | Sergei Petrunia <psergey@askmonty.org> | 2021-01-28 21:43:55 +0300 |
| commit | 998560e253d0bc1f251ca106f67b31f6684157df (patch) | |
| tree | b78fec8d911ea72d6fa60267c6cee95335b97c06 /sql/sys_vars.cc | |
| parent | 6d1f1b61b59310027698a92ccf533a3093f1ce04 (diff) | |
| download | mariadb-git-10.5-mdev9750.tar.gz | |
MDEV-9750: Quick memory exhaustion with 'extended_keys=on' ...10.5-mdev9750
(Variant #4, full patch)
Do not produce SEL_ARG graphs that would yield huge numbers of ranges.
Introduce a concept of SEL_ARG graph's "weight". If we are about to
produce a graph whose "weight" exceeds the limit, remove the parts
of SEL_ARG graph that represent the biggest key parts. Do so until
the graph's is within the limit.
Includes
- debug code to verify SEL_ARG graph weight
- A user-visible @@optimizer_max_sel_arg_weight to control the optimization
- Logging the optimization into the optimizer trace.
Diffstat (limited to 'sql/sys_vars.cc')
| -rw-r--r-- | sql/sys_vars.cc | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc index 12b6ea96182..f56bd5d8875 100644 --- a/sql/sys_vars.cc +++ b/sql/sys_vars.cc @@ -6693,6 +6693,12 @@ static Sys_var_uint Sys_in_subquery_conversion_threshold( SESSION_VAR(in_subquery_conversion_threshold), CMD_LINE(REQUIRED_ARG), VALID_RANGE(0, UINT_MAX), DEFAULT(IN_SUBQUERY_CONVERSION_THRESHOLD), BLOCK_SIZE(1)); +static Sys_var_ulong Sys_optimizer_max_sel_arg_weight( + "optimizer_max_sel_arg_weight", + "The maximum weight of the SEL_ARG graph. Set to 0 for no limit", + SESSION_VAR(optimizer_max_sel_arg_weight), CMD_LINE(REQUIRED_ARG), + VALID_RANGE(0, ULONG_MAX), DEFAULT(SEL_ARG::MAX_WEIGHT), BLOCK_SIZE(1)); + static Sys_var_enum Sys_secure_timestamp( "secure_timestamp", "Restricts direct setting of a session " "timestamp. Possible levels are: YES - timestamp cannot deviate from " |