Hi Sergei, 06.09.2013, в 15:29, Sergei Golubchik <s...@mariadb.org> написал(а):
> Hi, Sergey! > > On Sep 06, Sergey Vojtovich wrote: >> revno: 3878 >> revision-id: s...@mariadb.org-20130906111656-oy2c3pwy2o1q0zqn >> parent: w...@montyprogram.com-20130903204512-hgwu77prle0lw7a3 >> committer: Sergey Vojtovich <s...@mariadb.org> >> branch nick: 5.5-mdev4978 >> timestamp: Fri 2013-09-06 15:16:56 +0400 >> message: >> MDEV-4978 - Server cursor is broken with blobs in the select list, >> ORDER BY does not work >> >> Use "dynamic" row format (instead of "block") for MARIA internal >> temporary tables created for cursors. >> With "block" row format MARIA may shuffle rows, with "dynamic" row >> format records are inserted sequentially (there are no gaps in data >> file while we fill temporary tables). >> This is needed to preserve row order when scanning materialized cursors. > >> === modified file 'sql/sql_select.cc' >> --- a/sql/sql_select.cc 2013-09-03 14:41:07 +0000 >> +++ b/sql/sql_select.cc 2013-09-06 11:16:56 +0000 >> @@ -15373,7 +15374,8 @@ create_tmp_table(THD *thd, TMP_TABLE_PAR >> if (thd->is_fatal_error) // If end of memory >> goto err; /* purecov: inspected >> */ >> share->db_record_offset= 1; >> - table->used_for_duplicate_elimination= (param->sum_func_count == 0 && >> + table->used_for_duplicate_elimination= keep_row_order || >> + (param->sum_func_count == 0 && >> (table->group || table->distinct)); > > That's very confusing. Why keep_row_order means that the table is "used > for duplicate elimination"? > > I had to check the code to see that used_for_duplicate_elimination > affects the row format in Aria. This is not obvious too. > > And it forces the row format to be DYNAMIC for a very different reason, > not for preserving row order. Can't disagree. > > Perhaps it'd be better to rename used_for_duplicate_elimination to > "force_dynamic_Aria_row_format" ? A prettier solution would be to > introduce another flag: table->keep_row_order. I submitted another patch with the "prettier" solution. Though I tend to think that it'd be better not to fill TABLE object with things like keep_row_order and used_for_duplicate_elimination - they can go as an argument to create_internal_tmp_table(force_dynamic_aria_row_format). Thanks, Sergey > > Regards, > Sergei > _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
