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Optimising UNION ALL (WL 1687)

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Sinisa@sinisa.nasamreza.org
2004-05-15 16:13:08 +03:00
parent c745ae9503
commit 0806214620
1 changed files with 7 additions and 3 deletions
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10
sql/sql_union.cc
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@@ -339,8 +339,8 @@ int st_select_lex_unit::exec()
item->reset(); item->reset();
table->file->delete_all_rows(); table->file->delete_all_rows();
} }
if (union_distinct) // for subselects if (union_distinct && table->file->enable_indexes(HA_KEY_SWITCH_ALL))
table->file->extra(HA_EXTRA_CHANGE_KEY_TO_UNIQUE); DBUG_RETURN(1); // For sub-selects
for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select()) for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select())
{ {
ha_rows records_at_start= 0; ha_rows records_at_start= 0;
@@ -392,7 +392,11 @@ int st_select_lex_unit::exec()
records_at_start= table->file->records; records_at_start= table->file->records;
sl->join->exec(); sl->join->exec();
if (sl == union_distinct) if (sl == union_distinct)
table->file->extra(HA_EXTRA_CHANGE_KEY_TO_DUP); {
if (table->file->disable_indexes(HA_KEY_SWITCH_ALL))
DBUG_RETURN(1);
table->no_keyread=1;
}
res= sl->join->error; res= sl->join->error;
offset_limit_cnt= sl->offset_limit; offset_limit_cnt= sl->offset_limit;
if (!res && union_result->flush()) if (!res && union_result->flush())