Hi, Aleksey, On Oct 24, Aleksey Midenkov wrote: > > > diff --git a/storage/myisam/ha_myisam.cc b/storage/myisam/ha_myisam.cc > > > index ddab8bcf741..27151548704 100644 > > > --- a/storage/myisam/ha_myisam.cc > > > +++ b/storage/myisam/ha_myisam.cc > > > @@ -714,6 +714,8 @@ static int compute_vcols(MI_INFO *info, uchar > > > *record, int keynum) > > > /* This mutex is needed for parallel repair */ > > > mysql_mutex_lock(&info->s->intern_lock); > > > TABLE *table= (TABLE*)(info->external_ref); > > > + if (!current_thd) > > > + set_current_thd(table->in_use); > > > > why not to do it in thr_find_all_keys(), unconditionally? > > you'd avoid an if() executed per row. > > It is done only for repair, isn't it, so what are we supposed to > optimize by removing this if?
it's done for repair, for *every row* of the table, there can be many millions of rows. It's the condition that will be true for the first row and then it'll be always false. There is simply no reason to reevaluate it for every row. > > Also, I'd suggest a comment, like > > > > /* > > To evaluate vcols we must have current_thd set. > > This will set current_thd in all threads to the same THD, but it's > > safe, because vcols are always evaluated under info->s->intern_lock. > > */ > > This is self-explanatory for the code in compute_vcols(). Another > argument to keep that in compute_vcols(). If it would've been self-explanatory, I wouldn't have asked. Meaning it wasn't self-explanatory to me. Regards, Sergei Chief Architect, MariaDB Server and secur...@mariadb.org _______________________________________________ developers mailing list -- developers@lists.mariadb.org To unsubscribe send an email to developers-le...@lists.mariadb.org
