утилита для обслуживания таблиц MyISAM (MyISAM table-maintenance utility)
OTHER MYISAMCHK OPTIONS
myisamchk
supports the following options for actions other than
table checks and repairs:
• --analyze
, -a
Analyze the distribution of key values. This improves join
performance by enabling the join optimizer to better choose
the order in which to join the tables and which indexes it
should use. To obtain information about the key distribution,
use a myisamchk --description --verbose
tbl_name command or
the SHOW INDEX FROM tbl_name statement.
• --block-search=
offset, -b
offset
Find the record that a block at the given offset belongs to.
• --description
, -d
Print some descriptive information about the table.
Specifying the --verbose
option once or twice produces
additional information. See the section called 'MYISAMCHK
TABLE INFORMATION'.
• --set-auto-increment[=
value]
, -A[
value]
Force AUTO_INCREMENT numbering for new records to start at
the given value (or higher, if there are existing records
with AUTO_INCREMENT values this large). If value is not
specified, AUTO_INCREMENT numbers for new records begin with
the largest value currently in the table, plus one.
• --sort-index
, -S
Sort the index tree blocks in high-low order. This optimizes
seeks and makes table scans that use indexes faster.
• --sort-records=
N, -R
N
Sort records according to a particular index. This makes your
data much more localized and may speed up range-based SELECT
and ORDER BY operations that use this index. (The first time
you use this option to sort a table, it may be very slow.) To
determine a table´s index numbers, use SHOW INDEX, which
displays a table´s indexes in the same order that myisamchk
sees them. Indexes are numbered beginning with 1.
If keys are not packed (PACK_KEYS=0), they have the same
length, so when myisamchk
sorts and moves records, it just
overwrites record offsets in the index. If keys are packed
(PACK_KEYS=1), myisamchk
must unpack key blocks first, then
re-create indexes and pack the key blocks again. (In this
case, re-creating indexes is faster than updating offsets for
each index.)
• --stats-method=name
Specifies how index statistics collection code should treat
NULLs. Possible values of name are "nulls_unequal" (default),
"nulls_equal" (emulate MySQL 4 behavior), and
"nulls_ignored".