Hi, Sergey! On Sep 06, Sergey Vojtovich wrote: > revno: 3878 > revision-id: [email protected] > parent: [email protected] > committer: Sergey Vojtovich <[email protected]> > 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. 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. Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
