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'\" t .\" .TH "\FBMYISAMPACK\FR" "1" "14/12/2015" "MariaDB 10\&.1" "MariaDB Database System" .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .\" myisampack .\" compressed tables .\" tables: compressed .\" MyISAM: compressed tables .SH "NAME" myisampack \- generate compressed, read\-only MyISAM tables .SH "SYNOPSIS" .HP \w'\fBmyisampack\ [\fR\fB\fIoptions\fR\fR\fB]\ \fR\fB\fIfile_name\fR\fR\fB\ \&.\&.\&.\fR\ 'u \fBmyisampack [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fIfile_name\fR\fR\fB \&.\&.\&.\fR .SH "DESCRIPTION" .PP The \fBmyisampack\fR utility compresses MyISAM tables\&. \fBmyisampack\fR works by compressing each column in the table separately\&. Usually, \fBmyisampack\fR packs the data file 40%\(en70%\&. .PP 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\&. .PP 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\&. .PP Please note the following: .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} If the \fBmysqld\fR server was invoked with external locking disabled, it is not a good idea to invoke \fBmyisampack\fR if the table might be updated by the server during the packing process\&. It is safest to compress tables with the server stopped\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} After packing a table, it becomes read only\&. This is generally intended (such as when accessing packed tables on a CD)\&. .RE .PP Invoke \fBmyisampack\fR like this: .sp .if n \{\ .RS 4 .\} .nf shell> \fBmyisampack [\fR\fB\fIoptions\fR\fR\fB] \fR\fB\fIfile_name\fR\fR\fB \&.\&.\&.\fR .fi .if n \{\ .RE .\} .PP 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\&. .PP After you compress a table with \fBmyisampack\fR, you should use \fBmyisamchk \-rq\fR to rebuild its indexes\&. \fBmyisamchk\fR(1)\&. .PP \fBmyisampack\fR supports the following options\&. It also reads option files and supports the options for processing them described at Section\ \&4.2.3.3.1, \(lqCommand-Line Options that Affect Option-File Handling\(rq\&. .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: help option .\" help option: myisampack \fB\-\-help\fR, \fB\-?\fR .sp Display a help message and exit\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: backup option .\" backup option: myisampack \fB\-\-backup\fR, \fB\-b\fR .sp Make a backup of each table\'s data file using the name \fItbl_name\fR\&.OLD\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: character-sets-dir option .\" character-sets-dir option: myisampack \fB\-\-character\-sets\-dir=\fR\fB\fIpath\fR\fR .sp The directory where character sets are installed\&. See Section\ \&9.5, \(lqCharacter Set Configuration\(rq\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: debug option .\" debug option: myisampack \fB\-\-debug[=\fR\fB\fIdebug_options\fR\fR\fB]\fR, \fB\-# [\fR\fB\fIdebug_options\fR\fR\fB]\fR .sp Write a debugging log\&. A typical \fIdebug_options\fR string is \'d:t:o,\fIfile_name\fR\'\&. The default is \'d:t:o\'\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: force option .\" force option: myisampack \fB\-\-force\fR, \fB\-f\fR .sp Produce a packed table even if it becomes larger than the original or if the intermediate file from an earlier invocation of \fBmyisampack\fR exists\&. (\fBmyisampack\fR creates an intermediate file named \fItbl_name\fR\&.TMD in the database directory while it compresses the table\&. If you kill \fBmyisampack\fR, the \&.TMD file might not be deleted\&.) Normally, \fBmyisampack\fR exits with an error if it finds that \fItbl_name\fR\&.TMD exists\&. With \fB\-\-force\fR, \fBmyisampack\fR packs the table anyway\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: join option .\" join option: myisampack \fB\-\-join=\fR\fB\fIbig_tbl_name\fR\fR, \fB\-j \fR\fB\fIbig_tbl_name\fR\fR .sp Join all tables named on the command line into a single packed table \fIbig_tbl_name\fR\&. All tables that are to be combined \fImust\fR have identical structure (same column names and types, same indexes, and so forth)\&. .sp \fIbig_tbl_name\fR must not exist prior to the join operation\&. All source tables named on the command line to be merged into \fIbig_tbl_name\fR must exist\&. The source tables are read for the join operation but not modified\&. The join operation does not create a \&.frm file for \fIbig_tbl_name\fR, so after the join operation finishes, copy the \&.frm file from one of the source tables and name it \fIbig_tbl_name\fR\&.frm\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: silent option .\" silent option: myisampack \fB\-\-silent\fR, \fB\-s\fR .sp Silent mode\&. Write output only when errors occur\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: test option .\" test option: myisampack \fB\-\-test\fR, \fB\-t\fR .sp Do not actually pack the table, just test packing it\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: tmpdir option .\" tmpdir option: myisampack \fB\-\-tmpdir=\fR\fB\fIpath\fR\fR, \fB\-T \fR\fB\fIpath\fR\fR .sp Use the named directory as the location where \fBmyisampack\fR creates temporary files\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: verbose option .\" verbose option: myisampack \fB\-\-verbose\fR, \fB\-v\fR .sp Verbose mode\&. Write information about the progress of the packing operation and its result\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: version option .\" version option: myisampack \fB\-\-version\fR, \fB\-V\fR .sp Display version information and exit\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} .\" myisampack: wait option .\" wait option: myisampack \fB\-\-wait\fR, \fB\-w\fR .sp Wait and retry if the table is in use\&. If the \fBmysqld\fR server was invoked with external locking disabled, it is not a good idea to invoke \fBmyisampack\fR if the table might be updated by the server during the packing process\&. .RE .\" examples: compressed tables .PP The following sequence of commands illustrates a typical table compression session: .sp .if n \{\ .RS 4 .\} .nf shell> \fBls \-l station\&.*\fR \-rw\-rw\-r\-\- 1 monty my 994128 Apr 17 19:00 station\&.MYD \-rw\-rw\-r\-\- 1 monty my 53248 Apr 17 19:00 station\&.MYI \-rw\-rw\-r\-\- 1 monty my 5767 Apr 17 19:00 station\&.frm shell> \fBmyisamchk \-dvv station\fR MyISAM file: station Isam\-version: 2 Creation time: 1996\-03\-13 10:08:58 Recover time: 1997\-02\-02 3:06:43 Data records: 1192 Deleted blocks: 0 Datafile parts: 1192 Deleted data: 0 Datafile pointer (bytes): 2 Keyfile pointer (bytes): 2 Max datafile length: 54657023 Max keyfile length: 33554431 Recordlength: 834 Record format: Fixed length table description: Key Start Len Index Type Root Blocksize Rec/key 1 2 4 unique unsigned long 1024 1024 1 2 32 30 multip\&. text 10240 1024 1 Field Start Length Type 1 1 1 2 2 4 3 6 4 4 10 1 5 11 20 6 31 1 7 32 30 8 62 35 9 97 35 10 132 35 11 167 4 12 171 16 13 187 35 14 222 4 15 226 16 16 242 20 17 262 20 18 282 20 19 302 30 20 332 4 21 336 4 22 340 1 23 341 8 24 349 8 25 357 8 26 365 2 27 367 2 28 369 4 29 373 4 30 377 1 31 378 2 32 380 8 33 388 4 34 392 4 35 396 4 36 400 4 37 404 1 38 405 4 39 409 4 40 413 4 41 417 4 42 421 4 43 425 4 44 429 20 45 449 30 46 479 1 47 480 1 48 481 79 49 560 79 50 639 79 51 718 79 52 797 8 53 805 1 54 806 1 55 807 20 56 827 4 57 831 4 shell> \fBmyisampack station\&.MYI\fR Compressing station\&.MYI: (1192 records) \- Calculating statistics normal: 20 empty\-space: 16 empty\-zero: 12 empty\-fill: 11 pre\-space: 0 end\-space: 12 table\-lookups: 5 zero: 7 Original trees: 57 After join: 17 \- Compressing file 87\&.14% Remember to run myisamchk \-rq on compressed tables shell> \fBls \-l station\&.*\fR \-rw\-rw\-r\-\- 1 monty my 127874 Apr 17 19:00 station\&.MYD \-rw\-rw\-r\-\- 1 monty my 55296 Apr 17 19:04 station\&.MYI \-rw\-rw\-r\-\- 1 monty my 5767 Apr 17 19:00 station\&.frm shell> \fBmyisamchk \-dvv station\fR MyISAM file: station Isam\-version: 2 Creation time: 1996\-03\-13 10:08:58 Recover time: 1997\-04\-17 19:04:26 Data records: 1192 Deleted blocks: 0 Datafile parts: 1192 Deleted data: 0 Datafile pointer (bytes): 3 Keyfile pointer (bytes): 1 Max datafile length: 16777215 Max keyfile length: 131071 Recordlength: 834 Record format: Compressed table description: Key Start Len Index Type Root Blocksize Rec/key 1 2 4 unique unsigned long 10240 1024 1 2 32 30 multip\&. text 54272 1024 1 Field Start Length Type Huff tree Bits 1 1 1 constant 1 0 2 2 4 zerofill(1) 2 9 3 6 4 no zeros, zerofill(1) 2 9 4 10 1 3 9 5 11 20 table\-lookup 4 0 6 31 1 3 9 7 32 30 no endspace, not_always 5 9 8 62 35 no endspace, not_always, no empty 6 9 9 97 35 no empty 7 9 10 132 35 no endspace, not_always, no empty 6 9 11 167 4 zerofill(1) 2 9 12 171 16 no endspace, not_always, no empty 5 9 13 187 35 no endspace, not_always, no empty 6 9 14 222 4 zerofill(1) 2 9 15 226 16 no endspace, not_always, no empty 5 9 16 242 20 no endspace, not_always 8 9 17 262 20 no endspace, no empty 8 9 18 282 20 no endspace, no empty 5 9 19 302 30 no endspace, no empty 6 9 20 332 4 always zero 2 9 21 336 4 always zero 2 9 22 340 1 3 9 23 341 8 table\-lookup 9 0 24 349 8 table\-lookup 10 0 25 357 8 always zero 2 9 26 365 2 2 9 27 367 2 no zeros, zerofill(1) 2 9 28 369 4 no zeros, zerofill(1) 2 9 29 373 4 table\-lookup 11 0 30 377 1 3 9 31 378 2 no zeros, zerofill(1) 2 9 32 380 8 no zeros 2 9 33 388 4 always zero 2 9 34 392 4 table\-lookup 12 0 35 396 4 no zeros, zerofill(1) 13 9 36 400 4 no zeros, zerofill(1) 2 9 37 404 1 2 9 38 405 4 no zeros 2 9 39 409 4 always zero 2 9 40 413 4 no zeros 2 9 41 417 4 always zero 2 9 42 421 4 no zeros 2 9 43 425 4 always zero 2 9 44 429 20 no empty 3 9 45 449 30 no empty 3 9 46 479 1 14 4 47 480 1 14 4 48 481 79 no endspace, no empty 15 9 49 560 79 no empty 2 9 50 639 79 no empty 2 9 51 718 79 no endspace 16 9 52 797 8 no empty 2 9 53 805 1 17 1 54 806 1 3 9 55 807 20 no empty 3 9 56 827 4 no zeros, zerofill(2) 2 9 57 831 4 no zeros, zerofill(1) 2 9 .fi .if n \{\ .RE .\} .PP \fBmyisampack\fR displays the following kinds of information: .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} normal .sp The number of columns for which no extra packing is used\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} empty\-space .sp The number of columns containing values that are only spaces\&. These occupy one bit\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} empty\-zero .sp The number of columns containing values that are only binary zeros\&. These occupy one bit\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} empty\-fill .sp The number of integer columns that do not occupy the full byte range of their type\&. These are changed to a smaller type\&. For example, a BIGINT column (eight bytes) can be stored as a TINYINT column (one byte) if all its values are in the range from \-128 to 127\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} pre\-space .sp The number of decimal columns that are stored with leading spaces\&. In this case, each value contains a count for the number of leading spaces\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} end\-space .sp The number of columns that have a lot of trailing spaces\&. In this case, each value contains a count for the number of trailing spaces\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} table\-lookup .sp The column had only a small number of different values, which were converted to an ENUM before Huffman compression\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} zero .sp The number of columns for which all values are zero\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} Original trees .sp The initial number of Huffman trees\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} After join .sp The number of distinct Huffman trees left after joining trees to save some header space\&. .RE .PP After a table has been compressed, the Field lines displayed by \fBmyisamchk \-dvv\fR include additional information about each column: .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} Type .sp The data type\&. The value may contain any of the following descriptors: .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} constant .sp All rows have the same value\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} no endspace .sp Do not store endspace\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} no endspace, not_always .sp Do not store endspace and do not do endspace compression for all values\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} no endspace, no empty .sp Do not store endspace\&. Do not store empty values\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} table\-lookup .sp The column was converted to an ENUM\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} zerofill(\fIN\fR) .sp The most significant \fIN\fR bytes in the value are always 0 and are not stored\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} no zeros .sp Do not store zeros\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} always zero .sp Zero values are stored using one bit\&. .RE .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} Huff tree .sp The number of the Huffman tree associated with the column\&. .RE .sp .RS 4 .ie n \{\ \h'-04'\(bu\h'+03'\c .\} .el \{\ .sp -1 .IP \(bu 2.3 .\} Bits .sp The number of bits used in the Huffman tree\&. .RE .PP After you run \fBmyisampack\fR, you must run \fBmyisamchk\fR to re\-create any indexes\&. At this time, you can also sort the index blocks and create statistics needed for the MySQL optimizer to work more efficiently: .sp .if n \{\ .RS 4 .\} .nf shell> \fBmyisamchk \-rq \-\-sort\-index \-\-analyze \fR\fB\fItbl_name\fR\fR\fB\&.MYI\fR .fi .if n \{\ .RE .\} .PP After you have installed the packed table into the MySQL database directory, you should execute \fBmysqladmin flush\-tables\fR to force \fBmysqld\fR to start using the new table\&. .PP To unpack a packed table, use the \fB\-\-unpack\fR option to \fBmyisamchk\fR\&. .SH "COPYRIGHT" .br .PP Copyright 2007-2008 MySQL AB, 2008-2010 Sun Microsystems, Inc., 2010-2015 MariaDB Foundation .PP This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. .PP This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. .PP You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/. .sp .SH "SEE ALSO" For more information, please refer to the MariaDB Knowledge Base, available online at https://mariadb.com/kb/ .SH AUTHOR MariaDB Foundation (http://www.mariadb.org/).