Базы данныхИнтернетКомпьютерыОперационные системыПрограммированиеСетиСвязьРазное
Поиск по сайту:
Подпишись на рассылку:

Назад в раздел

Go to the first, previous, next, last section, table of contents.


12 MySQL Utilites

12.1 Overview of the different MySQL programs

All MySQL clients that communicate with the server using the mysqlclient library use the following environment variables:

Name Description
MYSQL_UNIX_PORT The default socket; used for connections to localhost
MYSQL_TCP_PORT The default TCP/IP port
MYSQL_PWD The default password
MYSQL_DEBUG Debug-trace options when debugging
TMPDIR The directory where temporary tables/files are created

Use of MYSQL_PWD is insecure. See section 6.5 Connecting to the MySQL server.

The `mysql' client uses the file named in the MYSQL_HISTFILE environment variable to save the command line history. The default value for the history file is `$HOME/.mysql_history', where $HOME is the value of the HOME environment variable.

All MySQL programs take many different options. However, every MySQL program provides a --help option that you can use to get a full description of the program's different options. For example, try mysql --help.

You can override default options for all standard client programs with an option file. section 4.15.4 Option files.

The list below briefly describes the MySQL programs:

myisamchk
Utility to describe, check, optimize and repair MySQL tables. Because myisamchk has many functions, it is described in its own chapter. See section 13 Maintaining a MySQL installation.
make_binary_release
Makes a binary release of a compiled MySQL. This could be sent by FTP to `/pub/mysql/Incoming' on ftp.tcx.se for the convenience of other MySQL users.
msql2mysql
A shell script that converts mSQL programs to MySQL. It doesn't handle all cases, but it gives a good start when converting.
mysql
mysql is a simple SQL shell (with GNU readline capabilities). It supports interactive and non-interactive use. When used interactively, query results are presented in an ASCII-table format. When used non-interactively (e.g., as a filter), the result is presented in tab-separated format. (The output format can be changed using command-line options.) You can run scripts simply like this:
shell> mysql database < script.sql > output.tab
If you have problems due to insufficient memory in the client, use the --quick option! This forces mysql to use mysql_use_result() rather than mysql_store_result() to retrieve the result set.
mysqlaccess
A script that checks the access privileges for a host, user and database combination.
mysqladmin
Utility for performing administrative operations, such as creating or dropping databases, reloading the grant tables, flushing tables to disk and reopening log files. mysqladmin can also be used to retrieve version, process and status information from the server. See section 12.2 Administering a MySQL server.
mysqlbug
The MySQL bug report script. This script should always be used when filing a bug report to the MySQL list.
mysqld
The SQL daemon. This should always be running.
mysqldump
Dumps a MySQL database into a file as SQL statements or as tab-separated text files. Enhanced freeware originally by Igor Romanenko. See section 12.3 Dumping the structure and data from MySQL databases and tables.
mysqlimport
Imports text files into their respective tables using LOAD DATA INFILE. See section 12.4 Importing data from text files.
mysqlshow
Displays information about databases, tables, columns and indexes.
mysql_install_db
Creates the MySQL grant tables with default privileges. This is usually executed only once, when first installing MySQL on a system.
replace
A utility program that is used by msql2mysql, but that has more general applicability as well. replace changes strings in place in files or on the standard input. Uses a finite state machine to match longer strings first. Can be used to swap strings. For example, this command swaps a and b in the given files:
shell> replace a b b a -- file1 file2 ...
safe_mysqld
A script that starts the mysqld daemon with some safety features, such as restarting the server when an error occurs and logging runtime information to a log file.

12.2 Administering a MySQL server

Utility for performing administrative operations. The syntax is:

shell> mysqladmin [OPTIONS] command [command-option] command ...

You can get a list of the options your version of mysqladmin supports by executing mysqladmin --help.

The current mysqladmin supports the following commands:

create databasename Create a new database.
drop databasename Delete a database and all its tables.
extended-status Gives an extended status message from the server.
flush-hosts Flush all cached hosts.
flush-logs Flush all logs.
flush-tables Flush all tables.
flush-privileges Reload grant tables (same as reload)
kill id,id,... Kill mysql threads.
password new-password Change old password to new-password
ping Check if mysqld is alive
processlist Show list of active threads in server
reload Reload grant tables
refresh Flush all tables and close and open logfiles
shutdown Take server down
status Gives a short status message from the server
variables Prints variables available
version Get version info from server

All commands can be shortened to their unique prefix. For example:

shell> mysqladmin proc stat
+----+-------+-----------+----+-------------+------+-------+------+
| Id | User  | Host      | db | Command     | Time | State | Info |
+----+-------+-----------+----+-------------+------+-------+------+
| 6  | monty | localhost |    | Processlist | 0    |       |      |
+----+-------+-----------+----+-------------+------+-------+------+
Uptime: 10077  Threads: 1  Questions: 9  Slow queries: 0  Opens: 6  Flush tables: 1  Open tables: 2  Memory in use: 1092K  Max memory used: 1116K

The mysqladmin status command result has the following columns:

Uptime Number of seconds the MySQL server have been up
Threads Number of active threads (clients)
Questions Number of questions from clients since mysqld was started
Slow queries Queries that has taken more than long_query_time seconds
Opens How many tables mysqld has opened.
Flush tables Number of flush ..., refresh and reload commands.
Open tables Number of tables that are open now
Memory in use Memory allocated directly by the mysqld code (only available when MySQL is compiled with --with-debug)
Max memory used Maximum memory allocated directly by the mysqld code (only available when MySQL is compiled with --with-debug)

12.3 Dumping the structure and data from MySQL databases and tables

Utility to dump a database or a collection of database for backup or for transferring the data to another SQL server. The dump will contain SQL statements to create the table and/or populate the table.

shell> mysqldump [OPTIONS] database [tables]

If you don't give any tables, the whole database will be dumped.

You can get a list of the options your version of mysqldump supports by executing mysqldump --help.

Note that if you run mysqldump without --quick or --opt, mysqldump will load the whole result set into memory before dumping the result. This will probably be a problem if you are dumping a big database.

mysqldump supports the following options:

--add-locks
Add LOCK TABLES before and UNLOCK TABLE after each table dump. (To get faster inserts into MySQL).
--add-drop-table
Add a drop table before each create statement.
--allow-keywords
Allow creation of column names that are keywords. This works by prefixing each column name with the table name.
-c, --complete-insert
Use complete insert statements (with column names).
-C, --compress
Compress all information between the client and the server if both support compression.
--delayed
Insert rows with the INSERT DELAYED command.
-e, --extended-insert
Use the new multiline INSERT syntax. (Gives more compact and faster inserts statements)
-#, --debug[=option_string]
Trace usage of the program (for debugging).
--help
Display a help message and exit.
--fields-terminated-by=...
--fields-enclosed-by=...
--fields-optionally-enclosed-by=...
--fields-escaped-by=...
--fields-terminated-by=...
These options are used with the -T option and have the same meaning as the corresponding clauses for LOAD DATA INFILE. See section 7.16 LOAD DATA INFILE syntax.
-F, --flush-logs
Flush logs file in the MySQL server before starting the dump.
-f, --force,
Continue even if we get an SQL error during a table dump.
-h, --host=..
Dump data from the MySQL server on the named host. The default host is localhost.
-l, --lock-tables.
Lock all tables for starting the dump.
-t, --no-create-info
Don't write table creation info (The CREATE TABLE statment)
-d, --no-data
Don't write any row information for the table. This is very useful if you just want to get a dump of the structure for a table!
--opt
Same as --quick --add-drop-table --add-locks --extended-insert --lock-tables. Should give you the fastest possible dump for reading into a MySQL server.
-pyour_pass, --password[=your_pass]
The password to use when connecting to the server. If you specify no `=your_pass' part, mysqldump solicits the password from the terminal.
-P port_num, --port=port_num
The TCP/IP port number to use for connecting to a host. (This is used for connections to hosts other than localhost, for which Unix sockets are used.)
-q, --quick
Don't buffer query, dump directly to stdout; Uses mysql_use_result() to do this.
-S /path/to/socket, --socket=/path/to/socket
The socket file to use when connecting to localhost (which is the default host).
-T, --tab=path-to-some-directory
Creates a table_name.sql file, that conntains the SQL CREATE commands, and a table_name.txt file, that contains the data, for each give table. NOTE: This only works if mysqldump is run on the same machine as the mysqld daemon. The format of the .txt file is made according to the --fields-xxx and --lines--xxx options.
-u user_name, --user=user_name
The MySQL user name to use when connecting to the server. The default value is your Unix login name.
-O var=option, --set-variable var=option
Set the value of a variable. The possible variables are listed below.
-v, --verbose
Verbose mode. Print out more information what the program does.
-V, --version
Print version information and exit.
-w, --where='where-condition'
Dump only selected records; Note that QUOTES are mandatory!
"--where=user='jimf'" "-wuserid>1" "-wuserid<1"

The most normal use of mysqldump is probably for making a backup of whole database:

mysqldump --opt database > backup-file.sql

But it's also very useful to populate another MySQL server with information from a database:

mysqldump --opt database | mysql --host=remote-host -C database

12.4 Importing data from text files

mysqlimport provides a command line interface to the LOAD DATA INFILE SQL statement. Most options to mysqlimport correspond directly to the same options to LOAD DATA INFILE. See section 7.16 LOAD DATA INFILE syntax.

mysqlimport is invoked like this:

shell> mysqlimport [options] database textfile1 [textfile2....]

For each text file named on the command line, mysqlimport strips any extension from the filename and uses the result to determine which table to import the file's contents into. For example, files named `patient.txt', `patient.text' and `patient' would all be imported into a table named patient.

mysqlimport supports the following options:

-C, --compress
Compress all information between the client and the server if both support compression.
-#, --debug[=option_string]
Trace usage of the program (for debugging).
-d, --delete
Empty the table before importing the text file.
--fields-terminated-by=...
--fields-enclosed-by=...
--fields-optionally-enclosed-by=...
--fields-escaped-by=...
--fields-terminated-by=...
These options have the same meaning as the corresponding clauses for LOAD DATA INFILE. See section 7.16 LOAD DATA INFILE syntax.
-f, --force
Ignore errors. For example, if a table for a text file doesn't exist, continue processing any remaining files. Without --force, mysqlimport exits if a table doesn't exist.
--help
Display a help message and exit.
-h host_name, --host=host_name
Import data to the MySQL server on the named host. The default host is localhost.
-i, --ignore
See the description for the --replace option.
-l, --lock-tables
Lock ALL tables for writing before processing any text files. This ensures that all tables are synchronized on the server.
-L, --local
Read input files from the client. By default, text files are assumed to be on the server if you connect to localhost (which is the default host).
-pyour_pass, --password[=your_pass]
The password to use when connecting to the server. If you specify no `=your_pass' part, mysqlimport solicits the password from the terminal.
-P port_num, --port=port_num
The TCP/IP port number to use for connecting to a host. (This is used for connections to hosts other than localhost, for which Unix sockets are used.)
-r, --replace
The --replace and --ignore options control handling of input records that duplicate existing records on unique key values. If you specify --replace, new rows replace existing rows that have the same unique key value. If you specify --ignore, input rows that duplicate an existing row on a unique key value are skipped. If you don't specify either option, an error occurs when a duplicate key value is found, and the rest of the text file is ignored.
-s, --silent
Silent mode. Write output only when errors occur.
-S /path/to/socket, --socket=/path/to/socket
The socket file to use when connecting to localhost (which is the default host).
-u user_name, --user=user_name
The MySQL user name to use when connecting to the server. The default value is your Unix login name.
-v, --verbose
Verbose mode. Print out more information what the program does.
-V, --version
Print version information and exit.

Here follows a sample run of using mysqlimport:

$ mysql --version
mysql  Ver 9.33 Distrib 3.22.25, for pc-linux-gnu (i686)
$ uname -a
Linux xxx.com 2.2.5-15 #1 Mon Apr 19 22:21:09 EDT 1999 i586 unknown
$ mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
$ ed
a
100     Max Sydow
101     Count Dracula
.
w imptest.txt
32
q
$ od -c imptest.txt
0000000   1   0   0  t   M   a   x       S   y   d   o   w  n   1   0
0000020   1  t   C   o   u   n   t       D   r   a   c   u   l   a  n
0000040
$ mysqlimport --local test imptest.txt
test.imptest: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0
$ mysql -e 'SELECT * FROM imptest' test
+------+---------------+
| id   | n             |
+------+---------------+
|  100 | Max Sydow     |
|  101 | Count Dracula |
+------+---------------+

12.5 The MySQL compressed read-only table generator

myisampack is used to compress MyISAM tables and pack_isam is used to compress ISAM tables. Since ISAM tables are deprecated we will only discuss myisampack here.

myisampack are an extra utility that you get when you order more than 10 licenses or extended support. Since these are distributed only in binary form, they are available only on some platforms.

In the following we only talk about myisampack, but everything holds also for pack_isam.

myisampack works by compressing each column in the table separately. The information needed to decompress columns is read into memory when the table is opened. This results in much better performance when accessing individual records, since you only have to uncompress exactly one record, not a much larger disk block like when using Stacker on MS-DOS. Usually, myisampack packs the data file 40%-70%.

MySQL uses memory mapping (mmap()) on compressed tables and falls back to normal read/write file usage if mmap() doesn't work.

There are currently two limitations with myisampack:

  • After packing, the table is read only.
  • myisampack can also pack BLOB or TEXT columns. The older pack_isam could not do this.

Fixing these limitations is on our TODO list but with low priority.

myisampack is invoked like this:

shell> myisampack [options] filename ...

Each filename should be the name of an index (`.MYI') file. If you are not in the database directory, you should specify the pathname to the file. It is permissible to omit the `.MYI' extension.

myisampack supports the following options:

-b, --backup
Make a backup of the table as tbl_name.OLD.
-#, --debug=debug_options
Output debug log. The debug_options string often is 'd:t:o,filename'.
-f, --force
Force packing of the table even if it becomes bigger or if the temporary file exists. (myisampack creates a temporary file named `tbl_name.TMD' while it compresses the table. If you kill myisampack, the `.TMD' file may not be deleted. Normally, myisampack exits with an error if it finds that `tbl_name.TMD' exists. With --force, myisampack packs the table anyway.
-?, --help
Display a help message and exit.
-j big_tbl_name, --join=big_tbl_name
Join all tables named on the command line into a single table big_tbl_name. All tables that are to be combined MUST be identical (same column names and types, same indexes, etc.)
-p #, --packlength=#
Specify the record length storage size, in bytes. The value should be 1, 2 or 3. (myisampack stores all rows with length pointers of 1, 2 or 3 bytes. In most normal cases, myisampack can determine the right length value before it begins packing the file, but it may notice during the packing process that it could have used a shorter length. In this case, myisampack will print a note that the next time you pack the same file, you could use a shorter record length.)
-s, --silent
Silent mode. Write output only when errors occur.
-t, --test
Don't pack table, only test packing it.
-T dir_name, --tmp_dir=dir_name
Use the named directory as the location in which to write the temporary table.
-v, --verbose
Verbose mode. Write info about progress and packing result.
-V, --version
Display version information and exit.
-w, --wait
Wait and retry if table is in use. If the mysqld server was invoked with the --skip-locking option, it is not a good idea to invoke myisampack if the table might be updated during the packing process.

The sequence of commands shown below illustrates a typical table compression session:

shell> ls -l station.*
-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> myisamchk -dvv station

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> myisampack station.MYI
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%

shell> ls -l station.*
-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> myisamchk -dvv station

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
Datafilepointer (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

The information printed by myisampack is described below:

normal
The number of columns for which no extra packing is used.
empty-space
The number of columns containing values that are only spaces; these will occupy 1 bit.
empty-zero
The number of columns containing values that are only binary 0's; these will occupy 1 bit.
empty-fill
The number of integer columns that don't occupy the full byte range of their type; these are changed to a smaller type (for example, an INTEGER column may be changed to MEDIUMINT).
pre-space
The number of decimal columns that are stored with leading space. In this case, each value will contain a count for the number of leading spaces.
end-space
The number of columns that have a lot of trailing space. In this case, each value will contain a count for the number of trailing spaces.
table-lookup
The column had only a small number of different values, and that were converted to an ENUM before Huffman compression.
zero
The number of columns for which all values are zero.
Original trees
The initial number of Huffman trees.
After join
The number of distinct Huffman trees left after joining trees to save some header space.

After a table has been compressed, myisamchk -dvv prints additional information about each field:

Type
The field type may contain the following descriptors:
constant
All rows have the same value.
no endspace
Don't store endspace.
no endspace, not_always
Don't store endspace and don't do end space compression for all values.
no endspace, no empty
Don't store endspace. Don't store empty values.
table-lookup
The column was converted to an ENUM.
zerofill(n)
The most significant n bytes in the value are always 0 and are not stored.
no zeros
Don't store zeros.
always zero
0 values are stored in 1 bit.
Huff tree
The Huffman tree associated with the field
Bits
The number of bits used in the Huffman tree.

After you have run pack_isam/myisampack you must run isamchk/myisamchk to recreate the index. At this time you can also sort the index blocks and create statistics that is needed for the MySQL optimizer to work more efficiently.

myisamchk -rq --analyze --sort-index table_name.MYI
isamchk   -rq --analyze --sort-index table_name.ISM

After you have installed the packed table into the MySQL database directory you should do mysqladmin flush-tables to force mysqld to start using the new table.


Go to the first, previous, next, last section, table of contents.


  • Главная
  • Новости
  • Новинки
  • Скрипты
  • Форум
  • Ссылки
  • О сайте




  • Emanual.ru – это сайт, посвящённый всем значимым событиям в IT-индустрии: новейшие разработки, уникальные методы и горячие новости! Тонны информации, полезной как для обычных пользователей, так и для самых продвинутых программистов! Интересные обсуждения на актуальные темы и огромная аудитория, которая может быть интересна широкому кругу рекламодателей. У нас вы узнаете всё о компьютерах, базах данных, операционных системах, сетях, инфраструктурах, связях и программированию на популярных языках!
     Copyright © 2001-2020
    Реклама на сайте