diff options
Diffstat (limited to 'sql/opt_range.cc')
| -rw-r--r-- | sql/opt_range.cc | 70 |
1 files changed, 53 insertions, 17 deletions
diff --git a/sql/opt_range.cc b/sql/opt_range.cc index 68734bcbef8..d47aa1ee41e 100644 --- a/sql/opt_range.cc +++ b/sql/opt_range.cc @@ -449,6 +449,7 @@ void print_range_for_non_indexed_field(String *out, Field *field, static void print_min_range_operator(String *out, const ha_rkey_function flag); static void print_max_range_operator(String *out, const ha_rkey_function flag); +static bool is_field_an_unique_index(RANGE_OPT_PARAM *param, Field *field); /* SEL_IMERGE is a list of possible ways to do index merge, i.e. it is @@ -7689,6 +7690,21 @@ SEL_TREE *Item_bool_func::get_ne_mm_tree(RANGE_OPT_PARAM *param, } +SEL_TREE *Item_func_ne::get_func_mm_tree(RANGE_OPT_PARAM *param, + Field *field, Item *value) +{ + DBUG_ENTER("Item_func_ne::get_func_mm_tree"); + /* + If this condition is a "col1<>...", where there is a UNIQUE KEY(col1), + do not construct a SEL_TREE from it. A condition that excludes just one + row in the table is not selective (unless there are only a few rows) + */ + if (is_field_an_unique_index(param, field)) + DBUG_RETURN(NULL); + DBUG_RETURN(get_ne_mm_tree(param, field, value, value)); +} + + SEL_TREE *Item_func_between::get_func_mm_tree(RANGE_OPT_PARAM *param, Field *field, Item *value) { @@ -7787,28 +7803,16 @@ SEL_TREE *Item_func_in::get_func_mm_tree(RANGE_OPT_PARAM *param, DBUG_RETURN(0); /* - If this is "unique_key NOT IN (...)", do not consider it sargable (for - any index, not just the unique one). The logic is as follows: + if this is a "col1 NOT IN (...)", and there is a UNIQUE KEY(col1), do + not constuct a SEL_TREE from it. The rationale is as follows: - if there are only a few constants, this condition is not selective (unless the table is also very small in which case we won't gain anything) - - If there are a lot of constants, the overhead of building and + - if there are a lot of constants, the overhead of building and processing enormous range list is not worth it. */ - if (param->using_real_indexes) - { - key_map::Iterator it(field->key_start); - uint key_no; - while ((key_no= it++) != key_map::Iterator::BITMAP_END) - { - KEY *key_info= &field->table->key_info[key_no]; - if (key_info->user_defined_key_parts == 1 && - (key_info->flags & HA_NOSAME)) - { - DBUG_RETURN(0); - } - } - } + if (is_field_an_unique_index(param, field)) + DBUG_RETURN(0); /* Get a SEL_TREE for "(-inf|NULL) < X < c_0" interval. */ uint i=0; @@ -8526,6 +8530,38 @@ SEL_TREE *Item_equal::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) } +/* + @brief + Check if there is an one-segment unique key that matches the field exactly + + @detail + In the future we could also add "almost unique" indexes where any value is + present only in a few rows (but necessarily exactly one row) +*/ +static bool is_field_an_unique_index(RANGE_OPT_PARAM *param, Field *field) +{ + DBUG_ENTER("is_field_an_unique_index"); + + // The check for using_real_indexes is there because of the heuristics + // this function is used for. + if (param->using_real_indexes) + { + key_map::Iterator it(field->key_start); + uint key_no; + while ((key_no= it++) != key_map::Iterator::BITMAP_END) + { + KEY *key_info= &field->table->key_info[key_no]; + if (key_info->user_defined_key_parts == 1 && + (key_info->flags & HA_NOSAME)) + { + DBUG_RETURN(true); + } + } + } + DBUG_RETURN(false); +} + + SEL_TREE * Item_bool_func::get_mm_parts(RANGE_OPT_PARAM *param, Field *field, Item_func::Functype type, Item *value) |