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MDEV-12580 Wrong query result in join when using an index (Version > "10.2.3")

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JOIN_TAB::remove_redundant_bnl_scan_conds() removes select_cond
from a JOIN_TAB if join cache is enabled, and tab->cache_select->cond
is the equal to tab->select_cond.

But after 8d99166c69 the code to initialize join cache was moved
to happen much later than JOIN_TAB::remove_redundant_bnl_scan_conds(),
and that code might, under certain conditions, revert to *not* using
join cache (set_join_cache_denial()).

If JOIN_TAB::remove_redundant_bnl_scan_conds() removes the WHERE
condition from the JOIN_TAB and later set_join_cache_denial() disables
join cache, we end up with no WHERE condition at all.

Fix: move JOIN_TAB::remove_redundant_bnl_scan_conds() to happen
after all possible set_join_cache_denial() calls.
This commit is contained in:
Sergei Golubchik
2017-05-06 14:00:19 +02:00
parent d6d7e169fb
commit d53eb85997
5 changed files with 38 additions and 15 deletions
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7
sql/sql_select.cc
View File

@ -1138,6 +1138,8 @@ int JOIN::init_join_caches()
}
if (tab->cache && tab->cache->init(select_options & SELECT_DESCRIBE))
revise_cache_usage(tab);
else
tab->remove_redundant_bnl_scan_conds();
}
return 0;
}
@ -11161,8 +11163,8 @@ void JOIN_TAB::remove_redundant_bnl_scan_conds()
select->cond is not processed separately. This method assumes it is always
the same as select_cond.
*/
DBUG_ASSERT(!select || !select->cond ||
(select->cond == select_cond));
if (select && select->cond != select_cond)
return;
if (is_cond_and(select_cond))
{
@ -11472,7 +11474,6 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
/* purecov: end */
}
tab->remove_redundant_bnl_scan_conds();
DBUG_EXECUTE("where",
char buff[256];
String str(buff,sizeof(buff),system_charset_info);