diff options
Diffstat (limited to 'sql/handler.h')
| -rw-r--r-- | sql/handler.h | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/sql/handler.h b/sql/handler.h index 3751af29194..c9a7d17e6dc 100644 --- a/sql/handler.h +++ b/sql/handler.h @@ -47,14 +47,22 @@ #define HA_ADMIN_WRONG_CHECKSUM -8 /* Bits in table_flags() to show what database can do */ -#define HA_READ_RND_SAME (1 << 0) /* can switch index during the scan - with ::rnd_same() - not used yet. - see mi_rsame/heap_rsame/myrg_rsame */ + +/* + Can switch index during the scan with ::rnd_same() - not used yet. + see mi_rsame/heap_rsame/myrg_rsame +*/ +#define HA_READ_RND_SAME (1 << 0) #define HA_TABLE_SCAN_ON_INDEX (1 << 2) /* No separate data/index file */ #define HA_REC_NOT_IN_SEQ (1 << 3) /* ha_info don't return recnumber; It returns a position to ha_r_rnd */ #define HA_CAN_GEOMETRY (1 << 4) -#define HA_FAST_KEY_READ (1 << 5) /* no need for a record cache in filesort */ +/* + Reading keys in random order is as fast as reading keys in sort order + (Used in records.cc to decide if we should use a record cache and by + filesort to decide if we should sort key + data or key + pointer-to-row +*/ +#define HA_FAST_KEY_READ (1 << 5) #define HA_NULL_IN_KEY (1 << 7) /* One can have keys with NULL */ #define HA_DUPP_POS (1 << 8) /* ha_position() gives dup row */ #define HA_NO_BLOBS (1 << 9) /* Doesn't support blobs */ @@ -62,9 +70,11 @@ #define HA_AUTO_PART_KEY (1 << 11) /* auto-increment in multi-part key */ #define HA_REQUIRE_PRIMARY_KEY (1 << 12) /* .. and can't create a hidden one */ #define HA_NOT_EXACT_COUNT (1 << 13) -#define HA_CAN_INSERT_DELAYED (1 << 14) /* only handlers with table-level locks - need no special code to support - INSERT DELAYED */ +/* + INSERT_DELAYED only works with handlers that uses MySQL internal table + level locks +*/ +#define HA_CAN_INSERT_DELAYED (1 << 14) #define HA_PRIMARY_KEY_IN_READ_INDEX (1 << 15) #define HA_NOT_DELETE_WITH_CACHE (1 << 18) #define HA_NO_PREFIX_CHAR_KEYS (1 << 20) |