Oracle 5.0, Справочное руководство

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myisampack
— Generate Compressed, Read-Only MyISAM Tables
334
Verbose mode. Print more output about what the program does. This option can be given multiple
times to produce more and more output.
•
-w write_file
Specify the write file.
•
-V
Display version information.
4.6.5.
myisampack
— Generate Compressed, Read-Only MyISAM Tables
The
myisampack
utility compresses
MyISAM
tables.
myisampack
works by compressing each column
in the table separately. Usually,
myisampack
packs the data file 40% to 70%.
When the table is used later, the server reads into memory the information needed to decompress
columns. This results in much better performance when accessing individual rows, because you only
have to uncompress exactly one row.
MySQL uses
mmap()
when possible to perform memory mapping on compressed tables. If
mmap()
does not work, MySQL falls back to normal read/write file operations.
Please note the following:
• If the
mysqld
server was invoked with external locking disabled, it is not a good idea to invoke
myisampack
if the table might be updated by the server during the packing process. It is safest to
compress tables with the server stopped.
• After packing a table, it becomes read only. This is generally intended (such as when accessing
packed tables on a CD).
Invoke
myisampack
like this:
shell> myisampack [options] file_name ...
Each file name argument should be the name of an index (
.MYI
) file. If you are not in the database
directory, you should specify the path name to the file. It is permissible to omit the
.MYI
extension.
After you compress a table with
myisampack
, you should use
myisamchk -rq
to rebuild its indexes.
Section 4.6.3, “
myisamchk
— MyISAM Table-Maintenance Utility” .
myisampack
supports the following options. It also reads option files and supports the options
for processing them described at Section 4.2.3.4, “Command-Line Options that Affect Option-File
Handling” .
•
--help
[334] ,
-?
Display a help message and exit.
•
--backup
[334] ,
-b
Make a backup of each table's data file using the name
tbl_name.OLD
.
•
--character-sets-dir=path
[334]
The directory where character sets are installed. See Section 10.5, “Character Set Configuration” .
•
--debug[=debug_options]
[334] ,
-# [debug_options]
Write a debugging log. A typical
debug_options
string is
'd:t:o,file_name'
. The default is
'd:t:o'
.
•
--force
[334] ,
-f