diff options
Diffstat (limited to 'sql/opt_range.cc')
| -rw-r--r-- | sql/opt_range.cc | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/sql/opt_range.cc b/sql/opt_range.cc index da6ede8586f..aa216849d76 100644 --- a/sql/opt_range.cc +++ b/sql/opt_range.cc @@ -567,19 +567,29 @@ SEL_ARG *SEL_ARG::clone_tree() return root; } -/***************************************************************************** -** Test if a key can be used in different ranges -** Returns: -** -1 if impossible select -** 0 if can't use quick_select -** 1 if found usable range -** Updates the following in the select parameter: -** needed_reg ; Bits for keys with may be used if all prev regs are read -** quick ; Parameter to use when reading records. -** In the table struct the following information is updated: -** quick_keys ; Which keys can be used -** quick_rows ; How many rows the key matches -*****************************************************************************/ +/* + Test if a key can be used in different ranges + + SYNOPSIS + SQL_SELECT::test_quick_select(thd,keys_to_use, prev_tables, + limit, force_quick_range) + + Updates the following in the select parameter: + needed_reg - Bits for keys with may be used if all prev regs are read + quick - Parameter to use when reading records. + In the table struct the following information is updated: + quick_keys - Which keys can be used + quick_rows - How many rows the key matches + + RETURN VALUES + -1 if impossible select + 0 if can't use quick_select + 1 if found usable range + + TODO + check if the function really needs to modify keys_to_use, and change the + code to pass it by reference if not +*/ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use, table_map prev_tables, |