diff options
Diffstat (limited to 'sql/sql_const.h')
-rw-r--r-- | sql/sql_const.h | 61 |
1 files changed, 11 insertions, 50 deletions
diff --git a/sql/sql_const.h b/sql/sql_const.h index 490b870d..1e5fef4a 100644 --- a/sql/sql_const.h +++ b/sql/sql_const.h @@ -119,8 +119,13 @@ #define CREATE_MODE 0 /* Default mode on new files */ #define NAMES_SEP_CHAR 255 /* Char to sep. names */ -#define READ_RECORD_BUFFER (uint) (IO_SIZE*8) /* Pointer_buffer_size */ -#define DISK_BUFFER_SIZE (uint) (IO_SIZE*16) /* Size of diskbuffer */ +/* + This is used when reading large blocks, sequential read. + We assume that reading this much will be roughly the same cost as 1 + seek / fetching one row from the storage engine. + Cost of one read of DISK_CHUNK_SIZE is DISK_SEEK_BASE_COST (ms). +*/ +#define DISK_CHUNK_SIZE (uint) (65536) /* Size of diskbuffer for tmpfiles */ #define FRM_VER_TRUE_VARCHAR (FRM_VER+4) /* 10 */ #define FRM_VER_EXPRESSSIONS (FRM_VER+5) /* 11 */ @@ -199,63 +204,19 @@ #define MIN_ROWS_TO_USE_TABLE_CACHE 100 #define MIN_ROWS_TO_USE_BULK_INSERT 100 -/** - The following is used to decide if MySQL should use table scanning - instead of reading with keys. The number says how many evaluation of the - WHERE clause is comparable to reading one extra row from a table. -*/ -#define TIME_FOR_COMPARE 5.0 // 5 WHERE compares == one read -#define TIME_FOR_COMPARE_IDX 20.0 - -#define IDX_BLOCK_COPY_COST ((double) 1 / TIME_FOR_COMPARE) -#define IDX_LOOKUP_COST ((double) 1 / 8) -#define MULTI_RANGE_READ_SETUP_COST (IDX_BLOCK_COPY_COST/10) - -/** - Number of comparisons of table rowids equivalent to reading one row from a - table. -*/ -#define TIME_FOR_COMPARE_ROWID (TIME_FOR_COMPARE*100) - -/* cost1 is better that cost2 only if cost1 + COST_EPS < cost2 */ -#define COST_EPS 0.001 - /* - For sequential disk seeks the cost formula is: - DISK_SEEK_BASE_COST + DISK_SEEK_PROP_COST * #blocks_to_skip - - The cost of average seek - DISK_SEEK_BASE_COST + DISK_SEEK_PROP_COST*BLOCKS_IN_AVG_SEEK =1.0. + The lower bound of accepted rows when using filter. + This is used to ensure that filters are not too agressive. */ -#define DISK_SEEK_BASE_COST ((double)0.9) - -#define BLOCKS_IN_AVG_SEEK 128 - -#define DISK_SEEK_PROP_COST ((double)0.1/BLOCKS_IN_AVG_SEEK) - +#define MIN_ROWS_AFTER_FILTERING 1.0 /** - Number of rows in a reference table when refereed through a not unique key. + Number of rows in a reference table when refered through a not unique key. This value is only used when we don't know anything about the key distribution. */ #define MATCHING_ROWS_IN_OTHER_TABLE 10 -/* - Subquery materialization-related constants -*/ -#define HEAP_TEMPTABLE_LOOKUP_COST 0.05 -#define DISK_TEMPTABLE_LOOKUP_COST 1.0 -#define SORT_INDEX_CMP_COST 0.02 - - -#define COST_MAX (DBL_MAX * (1.0 - DBL_EPSILON)) - -#define COST_ADD(c,d) (COST_MAX - (d) > (c) ? (c) + (d) : COST_MAX) - -#define COST_MULT(c,f) (COST_MAX / (f) > (c) ? (c) * (f) : COST_MAX) - - #define MY_CHARSET_BIN_MB_MAXLEN 1 /** Don't pack string keys shorter than this (if PACK_KEYS=1 isn't used). */ |