diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index efc710509e7..cb0f9e594ff 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -20633,7 +20633,15 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit, quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT || quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION || quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT) - ref_key= -1; + { + /* + we set ref_key=MAX_KEY instead of -1, because test_if_cheaper ordering + assumes that "ref_key==-1" means doing full index scan. + (This is not very straightforward and we got into this situation for + historical reasons. Should be fixed at some point). + */ + ref_key= MAX_KEY; + } else { ref_key= select->quick->index; @@ -25298,8 +25306,12 @@ static bool get_range_limit_read_cost(const JOIN_TAB *tab, @param table Table if tab == NULL or tab->table @param usable_keys Key map to find a cheaper key in @param ref_key - * 0 <= key < MAX_KEY - key number (hint) to start the search - * -1 - no key number provided + 0 <= key < MAX_KEY - Key that is currently used for finding + row + MAX_KEY - means index_merge is used + -1 - means we're currently not using an + index to find rows. + @param select_limit LIMIT value @param [out] new_key Key number if success, otherwise undefined @param [out] new_key_direction Return -1 (reverse) or +1 if success, @@ -25328,7 +25340,6 @@ test_if_cheaper_ordering(const JOIN_TAB *tab, ORDER *order, TABLE *table, uint *saved_best_key_parts) { DBUG_ENTER("test_if_cheaper_ordering"); - DBUG_ASSERT(ref_key < int(MAX_KEY)); /* Check whether there is an index compatible with the given order usage of which is cheaper than usage of the ref_key index (ref_key>=0) @@ -25393,7 +25404,7 @@ test_if_cheaper_ordering(const JOIN_TAB *tab, ORDER *order, TABLE *table, Calculate the selectivity of the ref_key for REF_ACCESS. For RANGE_ACCESS we use table->quick_condition_rows. */ - if (ref_key >= 0 && !is_hash_join_key_no(ref_key) && tab->type == JT_REF) + if (ref_key >= 0 && ref_key != MAX_KEY && tab->type == JT_REF) { if (table->quick_keys.is_set(ref_key)) refkey_rows_estimate= table->quick_rows[ref_key]; |