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Merge dl145s:/data/tkatchaounov/5.0-bug-21787

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into  neptunus.(none):/home/msvensson/mysql/mysql-5.0
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msvensson@neptunus.(none)
2006-09-04 11:45:43 +02:00
parent 1bea6cf1a2 462c22c1ae
commit 4d0430c8fd
3 changed files with 38 additions and 7 deletions
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21
sql/sql_select.cc
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@ -8994,11 +8994,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
keyinfo->key_length+= key_part_info->length;
}
}
else
{
set_if_smaller(table->s->max_rows, rows_limit);
param->end_write_records= rows_limit;
}
if (distinct && field_count != param->hidden_field_count)
{
@ -9013,8 +9008,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
null_pack_length-=hidden_null_pack_length;
keyinfo->key_parts= ((field_count-param->hidden_field_count)+
test(null_pack_length));
set_if_smaller(table->s->max_rows, rows_limit);
param->end_write_records= rows_limit;
table->distinct= 1;
table->s->keys= 1;
if (blob_count)
@ -9066,6 +9059,20 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
0 : FIELDFLAG_BINARY;
}
}
/*
Push the LIMIT clause to the temporary table creation, so that we
materialize only up to 'rows_limit' records instead of all result records.
This optimization is not applicable when there is GROUP BY or there is
no GROUP BY, but there are aggregate functions, because both must be
computed for all result rows.
*/
if (!group && !thd->lex->current_select->with_sum_func)
{
set_if_smaller(table->s->max_rows, rows_limit);
param->end_write_records= rows_limit;
}
if (thd->is_fatal_error) // If end of memory
goto err; /* purecov: inspected */
table->s->db_record_offset= 1;