MySQL 命令行工具之 mysqldump 深入研究，mysqlmysqldump

MySQL 命令行工具之 mysqldump 深入研究，mysqlmysqldump

mysqldump 是MySQL的一個命令行工具，用於邏輯備份。可以將數據庫和表的結構，以及表中的數據分別導出成：create database, create table, insert into的sql語句。當然也可以導出 存儲過程，觸發器，函數，調度事件(events)。不管是程序員，還是DBA都會經常使用的一個工具。

1. mysqldump --help

mysqldump 的選項很多，我們看一下他的幫助文檔：

mysqldump Ver 10.13 Distrib 5.6.26, for linux-glibc2.5 (i686) Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Dumping structure and contents of MySQL databases and tables. Usage: mysqldump [OPTIONS] database [tables] OR mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...] OR mysqldump [OPTIONS] --all-databases [OPTIONS] Default options are read from the following files in the given order: /etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf The following groups are read: mysqldump client The following options may be given as the first argument: --print-defaults Print the program argument list and exit. --no-defaults Don't read default options from any option file, except for login file. --defaults-file=# Only read default options from the given file #. --defaults-extra-file=# Read this file after the global files are read. --defaults-group-suffix=# Also read groups with concat(group, suffix) --login-path=# Read this path from the login file. -A, --all-databases Dump all the databases. This will be same as --databases with all databases selected. -Y, --all-tablespaces Dump all the tablespaces. -y, --no-tablespaces Do not dump any tablespace information. --add-drop-database Add a DROP DATABASE before each create. --add-drop-table Add a DROP TABLE before each create. (Defaults to on; use --skip-add-drop-table to disable.) --add-drop-trigger Add a DROP TRIGGER before each create. --add-locks Add locks around INSERT statements. (Defaults to on; use --skip-add-locks to disable.) --allow-keywords Allow creation of column names that are keywords. --apply-slave-statements Adds 'STOP SLAVE' prior to 'CHANGE MASTER' and 'START SLAVE' to bottom of dump. --bind-address=name IP address to bind to. --character-sets-dir=name Directory for character set files. -i, --comments Write additional information. (Defaults to on; use --skip-comments to disable.) --compatible=name Change the dump to be compatible with a given mode. By default tables are dumped in a format optimized for MySQL. Legal modes are: ansi, mysql323, mysql40, postgresql, oracle, mssql, db2, maxdb, no_key_options, no_table_options, no_field_options. One can use several modes separated by commas. Note: Requires MySQL server version 4.1.0 or higher. This option is ignored with earlier server versions. --compact Give less verbose output (useful for debugging). Disables structure comments and header/footer constructs. Enables options --skip-add-drop-table --skip-add-locks --skip-comments --skip-disable-keys --skip-set-charset. -c, --complete-insert Use complete insert statements. -C, --compress Use compression in server/client protocol. -a, --create-options Include all MySQL specific create options. (Defaults to on; use --skip-create-options to disable.) -B, --databases Dump several databases. Note the difference in usage; in this case no tables are given. All name arguments are regarded as database names. 'USE db_name;' will be included in the output. -#, --debug[=#] This is a non-debug version. Catch this and exit. --debug-check Check memory and open file usage at exit. --debug-info Print some debug info at exit. --default-character-set=name Set the default character set. --delayed-insert Insert rows with INSERT DELAYED. --delete-master-logs Delete logs on master after backup. This automatically enables --master-data. -K, --disable-keys '/*!40000 ALTER TABLE tb_name DISABLE KEYS */; and '/*!40000 ALTER TABLE tb_name ENABLE KEYS */; will be put in the output. (Defaults to on; use --skip-disable-keys to disable.) --dump-slave[=#] This causes the binary log position and filename of the master to be appended to the dumped data output. Setting the value to 1, will printit as a CHANGE MASTER command in the dumped data output; if equal to 2, that command will be prefixed with a comment symbol. This option will turn --lock-all-tables on, unless --single-transaction is specified too (in which case a global read lock is only taken a short time at the beginning of the dump - don't forget to read about --single-transaction below). In all cases any action on logs will happen at the exact moment of the dump.Option automatically turns --lock-tables off. -E, --events Dump events. -e, --extended-insert Use multiple-row INSERT syntax that include several VALUES lists. (Defaults to on; use --skip-extended-insert to disable.) --fields-terminated-by=name Fields in the output file are terminated by the given string. --fields-enclosed-by=name Fields in the output file are enclosed by the given character. --fields-optionally-enclosed-by=name Fields in the output file are optionally enclosed by the given character. --fields-escaped-by=name Fields in the output file are escaped by the given character. -F, --flush-logs Flush logs file in server before starting dump. Note that if you dump many databases at once (using the option --databases= or --all-databases), the logs will be flushed for each database dumped. The exception is when using --lock-all-tables or --master-data: in this case the logs will be flushed only once, corresponding to the moment all tables are locked. So if you want your dump and the log flush to happen at the same exact moment you should use --lock-all-tables or --master-data with --flush-logs. --flush-privileges Emit a FLUSH PRIVILEGES statement after dumping the mysql database. This option should be used any time the dump contains the mysql database and any other database that depends on the data in the mysql database for proper restore. -f, --force Continue even if we get an SQL error. -?, --help Display this help message and exit. --hex-blob Dump binary strings (BINARY, VARBINARY, BLOB) in hexadecimal format. -h, --host=name Connect to host. --ignore-table=name Do not dump the specified table. To specify more than one table to ignore, use the directive multiple times, once for each table. Each table must be specified with both database and table names, e.g., --ignore-table=database.table. --include-master-host-port Adds 'MASTER_HOST=<host>, MASTER_PORT=<port>' to 'CHANGE MASTER TO..' in dump produced with --dump-slave. --insert-ignore Insert rows with INSERT IGNORE. --lines-terminated-by=name Lines in the output file are terminated by the given string. -x, --lock-all-tables Locks all tables across all databases. This is achieved by taking a global read lock for the duration of the whole dump. Automatically turns --single-transaction and --lock-tables off. -l, --lock-tables Lock all tables for read. (Defaults to on; use --skip-lock-tables to disable.) --log-error=name Append warnings and errors to given file. --master-data[=#] This causes the binary log position and filename to be appended to the output. If equal to 1, will print it as a CHANGE MASTER command; if equal to 2, that command will be prefixed with a comment symbol. This option will turn --lock-all-tables on, unless --single-transaction is specified too (in which case a global read lock is only taken a short time at the beginning of the dump; don't forget to read about --single-transaction below). In all cases, any action on logs will happen at the exact moment of the dump. Option automatically turns --lock-tables off. --max-allowed-packet=# The maximum packet length to send to or receive from server. --net-buffer-length=# The buffer size for TCP/IP and socket communication. --no-autocommit Wrap tables with autocommit/commit statements. -n, --no-create-db Suppress the CREATE DATABASE ... IF EXISTS statement that normally is output for each dumped database if --all-databases or --databases is given. -t, --no-create-info Don't write table creation info. -d, --no-data No row information. -N, --no-set-names Same as --skip-set-charset. --opt Same as --add-drop-table, --add-locks, --create-options, --quick, --extended-insert, --lock-tables, --set-charset, and --disable-keys. Enabled by default, disable with --skip-opt. --order-by-primary Sorts each table's rows by primary key, or first unique key, if such a key exists. Useful when dumping a MyISAM table to be loaded into an InnoDB table, but will make the dump itself take considerably longer. -p, --password[=name] Password to use when connecting to server. If password is not given it's solicited on the tty. -P, --port=# Port number to use for connection. --protocol=name The protocol to use for connection (tcp, socket, pipe, memory). -q, --quick Don't buffer query, dump directly to stdout. (Defaults to on; use --skip-quick to disable.) -Q, --quote-names Quote table and column names with backticks (`). (Defaults to on; use --skip-quote-names to disable.) --replace Use REPLACE INTO instead of INSERT INTO. -r, --result-file=name Direct output to a given file. This option should be used in systems (e.g., DOS, Windows) that use carriage-return linefeed pairs (\r\n) to separate text lines. This option ensures that only a single newline is used. -R, --routines Dump stored routines (functions and procedures). --set-charset Add 'SET NAMES default_character_set' to the output. (Defaults to on; use --skip-set-charset to disable.) --set-gtid-purged[=name] Add 'SET @@GLOBAL.GTID_PURGED' to the output. Possible values for this option are ON, OFF and AUTO. If ON is used and GTIDs are not enabled on the server, an error is generated. If OFF is used, this option does nothing. If AUTO is used and GTIDs are enabled on the server, 'SET @@GLOBAL.GTID_PURGED' is added to the output. If GTIDs are disabled, AUTO does nothing. If no value is supplied then the default (AUTO) value will be considered. --single-transaction Creates a consistent snapshot by dumping all tables in a single transaction. Works ONLY for tables stored in storage engines which support multiversioning (currently only InnoDB does); the dump is NOT guaranteed to be consistent for other storage engines. While a --single-transaction dump is in process, to ensure a valid dump file (correct table contents and binary log position), no other connection should use the following statements: ALTER TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE, as consistent snapshot is not isolated from them. Option automatically turns off --lock-tables. --dump-date Put a dump date to the end of the output. (Defaults to on; use --skip-dump-date to disable.) --skip-opt Disable --opt. Disables --add-drop-table, --add-locks, --create-options, --quick, --extended-insert, --lock-tables, --set-charset, and --disable-keys. -S, --socket=name The socket file to use for connection. --secure-auth Refuse client connecting to server if it uses old (pre-4.1.1) protocol. (Defaults to on; use --skip-secure-auth to disable.) --ssl Enable SSL for connection (automatically enabled with other flags). --ssl-ca=name CA file in PEM format (check OpenSSL docs, implies --ssl). --ssl-capath=name CA directory (check OpenSSL docs, implies --ssl). --ssl-cert=name X509 cert in PEM format (implies --ssl). --ssl-cipher=name SSL cipher to use (implies --ssl). --ssl-key=name X509 key in PEM format (implies --ssl). --ssl-crl=name Certificate revocation list (implies --ssl). --ssl-crlpath=name Certificate revocation list path (implies --ssl). --ssl-verify-server-cert Verify server's "Common Name" in its cert against hostname used when connecting. This option is disabled by default. -T, --tab=name Create tab-separated textfile for each table to given path. (Create .sql and .txt files.) NOTE: This only works if mysqldump is run on the same machine as the mysqld server. --tables Overrides option --databases (-B). --triggers Dump triggers for each dumped table. (Defaults to on; use --skip-triggers to disable.) --tz-utc SET TIME_ZONE='+00:00' at top of dump to allow dumping of TIMESTAMP data when a server has data in different time zones or data is being moved between servers with different time zones. (Defaults to on; use --skip-tz-utc to disable.) -u, --user=name User for login if not current user. -v, --verbose Print info about the various stages. -V, --version Output version information and exit. -w, --where=name Dump only selected records. Quotes are mandatory. -X, --xml Dump a database as well formed XML. --plugin-dir=name Directory for client-side plugins. --default-auth=name Default authentication client-side plugin to use. Variables (--variable-name=value) and boolean options {FALSE|TRUE} Value (after reading options) --------------------------------- ---------------------------------------- all-databases FALSE all-tablespaces FALSE no-tablespaces FALSE add-drop-database FALSE add-drop-table TRUE add-drop-trigger FALSE add-locks TRUE allow-keywords FALSE apply-slave-statements FALSE bind-address (No default value) character-sets-dir (No default value) comments TRUE compatible (No default value) compact FALSE complete-insert FALSE compress FALSE create-options TRUE databases FALSE debug-check FALSE debug-info FALSE default-character-set utf8 delayed-insert FALSE delete-master-logs FALSE disable-keys TRUE dump-slave 0 events FALSE extended-insert TRUE fields-terminated-by (No default value) fields-enclosed-by (No default value) fields-optionally-enclosed-by (No default value) fields-escaped-by (No default value) flush-logs FALSE flush-privileges FALSE force FALSE hex-blob FALSE host (No default value) include-master-host-port FALSE insert-ignore FALSE lines-terminated-by (No default value) lock-all-tables FALSE lock-tables TRUE log-error (No default value) master-data 0 max-allowed-packet 25165824 net-buffer-length 1046528 no-autocommit FALSE no-create-db FALSE no-create-info FALSE no-data FALSE order-by-primary FALSE port 0 quick TRUE quote-names TRUE replace FALSE routines FALSE set-charset TRUE single-transaction FALSE dump-date TRUE socket /var/lib/mysql/mysql.sock secure-auth TRUE ssl FALSE ssl-ca (No default value) ssl-capath (No default value) ssl-cert (No default value) ssl-cipher (No default value) ssl-key (No default value) ssl-crl (No default value) ssl-crlpath (No default value) ssl-verify-server-cert FALSE tab (No default value) triggers TRUE tz-utc TRUE user (No default value) verbose FALSE where (No default value) plugin-dir (No default value) default-auth (No default value) mysqldump --help

總體看來，幫組文檔分成了兩個部分。前一個部分是對各種選項的說明，後一個部分是mysqldump的各種選項的默認值。

我們看到mysqldump擁有超多的選項，說明它很靈活，功能很強大。為了好理解，可以將他的眾多的選項和參數，根據他們的功能分為幾個類別來介紹。

在此之前，我們還要搞清楚mysqldump的所有的默認選項的值，它們的含義。

2. mysqldump 默認選項：

Variables (--variable-name=value)
and boolean options {FALSE|TRUE}  Value (after reading options)
--------------------------------- ----------------------------------------
all-databases                     FALSE
all-tablespaces                   FALSE
no-tablespaces                    FALSE
add-drop-database                 FALSE
add-drop-table                    TRUE
add-drop-trigger                  FALSE
add-locks                         TRUE
allow-keywords                    FALSE
apply-slave-statements            FALSE
bind-address                      (No default value)
character-sets-dir                (No default value)
comments                          TRUE
compatible                        (No default value)
compact                           FALSE
complete-insert                   FALSE
compress                          FALSE
create-options                    TRUE
databases                         FALSE
debug-check                       FALSE
debug-info                        FALSE
default-character-set             utf8
delayed-insert                    FALSE
delete-master-logs                FALSE
disable-keys                      TRUE
dump-slave                        0
events                            FALSE
extended-insert                   TRUE
fields-terminated-by              (No default value)
fields-enclosed-by                (No default value)
fields-optionally-enclosed-by     (No default value)
fields-escaped-by                 (No default value)
flush-logs                        FALSE
flush-privileges                  FALSE
force                             FALSE
hex-blob                          FALSE
host                              (No default value)
include-master-host-port          FALSE
insert-ignore                     FALSE
lines-terminated-by               (No default value)
lock-all-tables                   FALSE
lock-tables                       TRUE
log-error                         (No default value)
master-data                       0
max-allowed-packet                25165824
net-buffer-length                 1046528
no-autocommit                     FALSE
no-create-db                      FALSE
no-create-info                    FALSE
no-data                           FALSE
order-by-primary                  FALSE
port                              0
quick                             TRUE
quote-names                       TRUE
replace                           FALSE
routines                          FALSE
set-charset                       TRUE
single-transaction                FALSE
dump-date                         TRUE
socket                            /var/lib/mysql/mysql.sock
secure-auth                       TRUE
ssl                               FALSE
ssl-ca                            (No default value)
ssl-capath                        (No default value)
ssl-cert                          (No default value)
ssl-cipher                        (No default value)
ssl-key                           (No default value)
ssl-crl                           (No default value)
ssl-crlpath                       (No default value)
ssl-verify-server-cert            FALSE
tab                               (No default value)
triggers                          TRUE
tz-utc                            TRUE
user                              (No default value)
verbose                           FALSE
where                             (No default value)
plugin-dir                        (No default value)
default-auth                      (No default value)

這些默認值，有的是 false, 有的是 true，有的沒有默認值。我們要關注的是 默認為 true，也就是 mysqldump 默認給我打開的選擇：

add-drop-table                    TRUE 表示在生成表結構語句之前，生成對應的 DROP TABLE IF EXISTS `table_name`; 語句
add-locks                         TRUE 表示在生成表中數據的 insert into `table_name` values(...) 之前生成 LOCK TABLES `tab` WRITE;語句
comments                          TRUE 表示生成備注，就是所有 -- 開頭的說明，比如：-- Dumping data for  for table `tab`. 最好還是啟用；
create-options                    TRUE 表示在生成表結構時會生成：ENGINE=InnoDB AUTO_INCREMENT=827 DEFAULT CHARSET=utf8; 附加建表選項
default-character-set             utf8 指定語句：/*!40101 SET NAMES utf8 */;中的字符集；可能你需要改成 --default-character-set=utf8mb4
disable-keys                      TRUE 表示生產 insert 語句之前，生成：/*!40000 ALTER TABLE `tbl` DISABLE KEYS */; 可以加快insert速度；
extended-insert                   TRUE 表示生產的 insert 是 insert into `tbl` values(...),(...),(...) 表中所有行的數據合並成一條insert； 
lock-tables                       TRUE 表示在導出的過程中會鎖定所有表；
max-allowed-packet                25165824 最大支持 24M 的數據包；
net-buffer-length                 1046528  1M大小的socket buffer
quick                             TRUE 表示在導出語句時，不緩存，直接輸出到控制台或者文件中；
quote-names                       TRUE 表示對表名和列名使用 `` 符號包裹；防止它們是關鍵字時會出錯;
set-charset                       TRUE default-character-set=utf8指定字符集，而--set-charset=1/0 表示是否生成/*!40101 SET NAMES utf8 */; 
dump-date                         TRUE 表示是否在導出文件的末尾生成導出時間：-- Dump completed on 2015-09-15 11:15:10 
secure-auth                       TRUE 表示登錄判斷密碼時使用新的加密算法，拒絕就的加密算法
triggers                          TRUE 表示生成觸發器腳本；
tz-utc                            TRUE 表示是否生成：/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */; /*!40103 SET TIME_ZONE='+00:00' */;

如果要關閉這些打開的默認選項時，需要明確指定：mysqldump -uxxx -p aazj --extended-insert=0 Users > Users.sql; =0 表示關閉選項。

上面這些默認選項，最好結合一個例子來理解：

-- MySQL dump 10.13  Distrib 5.6.26, for linux-glibc2.5 (i686)
--
-- Host: localhost    Database: gs
-- ------------------------------------------------------
-- Server version    5.6.26-log

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;

--
-- Current Database: `gs`
--

CREATE DATABASE /*!32312 IF NOT EXISTS*/ `gs` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin */;

USE `gs`;

--
-- Table structure for table `user`
--

DROP TABLE IF EXISTS `user`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(30) COLLATE utf8mb4_bin DEFAULT NULL,
  `sex` tinyint(4) DEFAULT NULL,
  `phone` varchar(20) COLLATE utf8mb4_bin DEFAULT NULL,
  `addr` varchar(255) COLLATE utf8mb4_bin DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
/*!40101 SET character_set_client = @saved_cs_client */;

--
-- Dumping data for table `user`
--

LOCK TABLES `user` WRITE;
/*!40000 ALTER TABLE `user` DISABLE KEYS */;
INSERT INTO `user` VALUES (1,'yuanfang',1,'14465463786','hangzhou'),(2,'Andy',0,'14465463786','beijing'),(3,'peter',0,'14465463786','Hongkong');
/*!40000 ALTER TABLE `user` ENABLE KEYS */;
UNLOCK TABLES;
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

-- Dump completed on 2015-10-22 10:16:37

2. mysqldump 登錄連接服務器的相關選項

Default options are read from the following files in the given order:

/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf

The following groups are read: mysqldump client
The following options may be given as the first argument:
--no-defaults           Don't read default options from any option file, except for login file.
--defaults-file=#       Only read default options from the given file #.
--defaults-extra-file=# Read this file after the global files are read.
--defaults-group-suffix=# Also read groups with concat(group, suffix)
--login-path=#          Read this path from the login file.

1）mysqldump 作為一個客戶端工具，它會去尋找 my.cnf 文件，然後讀取該文件中 [mysqldump] 和 [client] 配置下面的選項；

2）那些 defaults 相關的選項都是為了另外指定 配置文件和登錄文件，極少使用；

  -u, --user=name     User for login if not current user.

  -p, --password[=name] Password to use when connecting to server. If password is not given it's solicited on the tty.

  -h, --host=name     Connect to host.

  -P, --port=#        Port number to use for connection.
  --protocol=name     The protocol to use for connection (tcp, socket, pipe, memory).

  --max-allowed-packet=#  The maximum packet length to send to or receive from server.
  --net-buffer-length=#      The buffer size for TCP/IP and socket communication.

3）這幾個選項指定 登錄的用戶名，密碼，mysqld IP地址，端口，連接使用的協議等等。

    一般常用的是 -h192.168.2.xx -uxxx -p ，如果mysqld默認端口不是3306，則需要使用 -Pxxx 指定端口.

    --max-allowed-packet 我們一般配置在my.cnf中。--net-buffer-length 是為了優化網絡連接的socket buffer.

使用示例： mysqldump -h192.168.1.20 -uxxx -p -P3057

3. mysqldump 備份內容的相關選項

我們可以選擇備份所有數據庫，某幾個數據庫，某一個數據庫，某一個數據庫中的某幾個表，某一個數據庫中的一個表；

可以選擇是否備份 存儲過程和函數，觸發器，調度事件.

1）選擇導出的數據庫 和 表：

-A, --all-databases Dump all the databases. This will be same as --databases with all databases selected.

-B, --databases     Dump several databases. Note the difference in usage; in this case no tables are given. All name arguments are

                            regarded as database names. 'USE db_name;' will be included in the output.

database [tables]   導出數據庫 database 中的表結構 和 表中數據；

2）選擇是否導出 建庫，建表語句，是否導出 表中的數據：

-n, --no-create-db  Suppress the CREATE DATABASE ... IF NOT EXISTS statement that normally is output for each dumped database if 

                             --all-databases or --databases is given. (不導出建庫語句: CREATE DATABASE，也就是不導庫結構)

-t, --no-create-info Don't write table creation info. (不導出建表語句)

-d, --no-data         No row information. (不導出數據，有時我們僅僅需要導出表結構，也就是建表語句就行了)

3）選擇是否導出 存儲過程和函數，觸發器，調度事件：

-R, --routines      Dump stored routines (functions and procedures). (導出存儲過程和函數)

--triggers            Dump triggers for each dumped table. (Defaults to on; use --skip-triggers to disable.) (導出觸發器)

--skip-triggers     不導出觸發器

-E, --events        Dump events. 導出調度事件(根據備份的目的進行選擇，如果是搭建slave，那麼就不要導出events.)

4）指定不導出 某個庫的某個表：

--ignore-table=name   Do not dump the specified table. To specify more than one table to ignore, use the directive multiple times,

                                 once for each table.  Each table must be specified with both database and table names,

                                 e.g.,  --ignore-table=database.table. (在導出數據庫時，排除某個或者某幾個表不導出)

5) 按照 where 條件導出：

   -w, --where='where_condition' Dump only selected records. Quotes are mandatory.

6）使用示例：

Dumping structure and contents of MySQL databases and tables.
Usage: mysqldump [OPTIONS] database [tables]
OR       mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...]
OR       mysqldump [OPTIONS] --all-databases [OPTIONS]

1> 導出單表的結構和數據：mysqldump -uxxx -p db1 tb1 > tb1.sql; 導出數據庫 db1 中的 表 tb1 的表結構 和 表中數據；

2> 導出多表的結構和數據：mysqldump -uxxx -p db1 tb1 tb2 > tb1_tb2.sql; 導出數據庫 db1 中的 表 tb1、tb2 的表結構 和 表中數據；

3> 導出單表的結構：mysqldump -uxxx -p --no-data db1 tb1 > tb1.sql; 導出數據庫 db1 中的 表 tb1 的表結構; 其實也可以使用: show create table tb1

4> 我們無法使用 mysqldump 到達 只導出某個或某幾個表的數據，而不導出建表語句的目的。

     但是我們可以使用 select * from table into outfile 'file.sql', 比如：select * from Users into outfile '/tmp/Users.sql'; 注意需要對目錄的寫權限。

5> 導出單個庫中庫結構、表結構、表數據：mysqldump -uxxx -p --databases db1 > db1.sql

6> 導出多個庫中庫結構、表結構、表數據：mysqldump -uxxx -p --databases db1 db2 > db1_db2.sql

7> 導出單個庫中庫結構、表結構、不要表數據：mysqldump -uxxx -p --no-data --databases db1 > db1.sql

8> 導出單個庫中數據，不要庫結構和表結構：mysqldump -uxxx -p --no-create-db --no-create-info --databases db1 > db1.sql

9> 導出多個庫中庫結構、表結構、不要表數據：mysqldump -uxxx -p --no-data --databases db1 db2 > db1_db2.sql

10> 導出數據庫中所有 庫 的庫結構，表結構，數據：mysqldump -uxxx -p --all-databases > all.sql

11> 導出數據庫中所有 庫 的庫結構，表結構，不要數據：mysqldump -uxxx -p --all-databases --no-data > all.sql

12> 導出單個庫中庫結構、表結構、表數據，排除某個表：mysqldump -uxxx -p --databases db1 --ignore-table=db1.test > db1.sql

4. mysqldump 事務 和 數據一致性(鎖) 的相關選項

在使用mysqldump邏輯備份時，事務和數據一致性的選項時至關重要的。

1） --single-transaction
      Creates a consistent snapshot by dumping all tables in a single transaction. Works ONLY for tables stored in storage engines which

      support multiversioning (currently only InnoDB does); the dump is NOT guaranteed to be consistent for other storage engines.

      While a --single-transaction dump is in process, to ensure a valid dump file (correct table contents and binary log position), no other

      connection should use the following statements: ALTER TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE, as consistent

      snapshot is not isolated from them. Option automatically turns off --lock-tables.

     --single-transaction 可以得到一致性的導出結果。他是通過將導出行為放入一個單事務中達到目的的。它會在導出的開始時持有一個全局的讀鎖。

     它有一些要求：只能是 innodb 引擎；導出的過程中，不能有任何人執行 alter table, drop table, rename table, truncate table等DDL語句。

     --single-transaction 會自動關閉 --lock-tables 選項；上面我們說到mysqldump默認會打開了--lock-tables，它會在導出過程中鎖定所有表。

    因為 --single-transaction 會自動關閉--lock-tables，所以單獨使用--single-transaction是不會使用鎖的。與 --master-data 合用才有鎖。

2）--lock-tables

     該選項默認打開的，上面已經說到了。它的作用是在導出過程中鎖定所有表。--single-transaction 和 --lock-all-tables 都會將該選項關閉。

3）--lock-all-tables
       Locks all tables across all databases. This is achieved by taking a global read lock for the duration of the whole dump.
       Automatically turns --single-transaction and --lock-tables off. 啟用該選項，會自動關閉 --single-transaction 和 --lock-tables.

上面三個選項中，只有 --lock-tables 默認是打開的；打開 --single-transaction 或者 打開 --lock-all-tables 都將關閉 --lock-tables. 而--lock-all-tables會自動關閉 --single-transaction 和 --lock-tables。所以三者是互斥的。我們應該一次只啟用其中一個選項。

4）--flush-logs   

        Flush logs file in server before starting dump. Note that if you dump many databases at once (using the option --databases= or

        --all-databases), the logs will be flushed for each database dumped. The exception is when using --lock-all-tables or

        --master-data: in this case the logs will be flushed only once, corresponding to the moment all tables are locked. So if you want your

       dump and the log flush to happen at the same exact moment you should use --lock-all-tables or --master-data with --flush-logs.

       為了獲得導出數據和刷新日志的一致性(同時發生)，必須將 --flush-logs 選項和 --lock-all-tables 或者 --master-data 以前使用：

       mysqldump --flush-logs --lock-all-tables;  mysqldump --flush-logs --master-data=2 ；

5）--flush-privileges 

      Emit a FLUSH PRIVILEGES statement after dumping the mysql database.  This option should be used any time the dump contains the

      mysql database and any other database that depends on the data in the mysql database for proper restore.

      如何導出包含了mysql數據，就應該啟用該選項。該選項會在導出的 mysql 數據庫的後面加上 flush privileges 語句，因為在向mysql數據庫inert了語句

      之後，必須使用 flush privileges，不然權限不生效。下面是例子：

6）  --master-data[=#]  

       This causes the binary log position and filename to be appended to the output. If equal to 1, will print it as a CHANGE MASTER

       command; if equal to 2, that command will be prefixed with a comment symbol. This option will turn --lock-all-tables on, unless

       --single-transaction is specified too (in which case a global read lock is only taken a short time at the beginning of the dump; don't
       forget to read about --single-transaction below). In all cases, any action on logs will happen at the exact moment of the dump.

       Option automatically turns --lock-tables off.

所以為了獲得一致性的備份數據和在備份是同時刷新binary日志，我們應該如下結合使用這些選項(完美組合)：

mysqldump -uxxx -pxxx --single-transaction --master-data=2 --flush-logs --routines

--databases db1 > db1.sql; (其中 --flush-logs 不是必須的; 搭建slave時，不要導出events，但是需要導出rountines.)

其中被 --master-data 打開的 --lock-all-tables 選項，又被 --single-transaction 關閉掉了。--flush-logs 借助於 --master-data 可以達到即使一次導出多個數據庫時，其 flush 的二進制日志也是在同一個時間點的，不是每一個數據庫flush一次的。並且這個時間點 和 --master-data 記錄的 binary log position 和 binary log file是同一個時間點，這些都是利用了 --single-transaction 和 --master-data 合用時短暫的使用一個全局的讀鎖來達到目的的。

5. mysqldump 復制 的相關選項