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Mysqldump备份流程

mysqldump 备份出的文件就是 sql 文件，其核心就是对每个表执行 select ，然后转化成相应的 insert 语句。

mysqldump 的备份流程大致如下：

1. 对某个库下所有表加读锁；
2. 循环备份备份表数据；
3. 释放读锁；
4. 循环上面三个步骤；
5. 备份完毕。

一. mysqldump命令备份数据

在MySQL中提供了命令行导出数据库数据以及文件的一种方便的工具mysqldump,我们可以通过命令行直接实现数据库内容的导出dump,首先我们简单了解一下mysqldump命令用法:

#MySQLdump常用
mysqldump -u root -p --databases 数据库1 数据库2 > xxx.sql

二. mysqldump常用操作示例

#1. 备份全部数据库的数据和结构
mysqldump -uroot -p123456 -A > /data/mysqlDump/mydb.sql


#2.备份全部数据库的结构（加 -d 参数）
mysqldump -uroot -p123456 -A -d > /data/mysqlDump/mydb.sql


#3. 备份全部数据库的数据(加 -t 参数)
mysqldump -uroot -p123456 -A -t > /data/mysqlDump/mydb.sql


#4.备份单个数据库的数据和结构(,数据库名mydb)
mysqldump -uroot-p123456 mydb > /data/mysqlDump/mydb.sql

#5. 备份单个数据库的结构
mysqldump -uroot -p123456 mydb -d > /data/mysqlDump/mydb.sql


#6. 备份单个数据库的数据
mysqldump -uroot -p123456 mydb -t > /data/mysqlDump/mydb.sql


#7. 备份多个表的数据和结构（数据，结构的单独备份方法与上同）
mysqldump -uroot -p123456 mydb t1 t2 > /data/mysqlDump/mydb.sql


#8. 一次备份多个数据库
mysqldump -uroot -p123456 --databases db1 db2 > /data/mysqlDump/mydb.sql

三. 还原 MySQL备份内容

有两种方式还原，第一种是在 MySQL 命令行中，第二种是使用 SHELL 行完成还原

#1. 在系统命令行中，输入如下实现还原：
mysql -uroot -p123456 < /data/mysqlDump/mydb.sql

#2. 在登录进入mysql系统中,通过source指令找到对应系统中的文件进行还原：
mysql> source /data/mysqlDump/mydb.sql

mysqldump cmd

[ sysadmin:~ ]# mysqldump --help
mysqldump  Ver 10.13 Distrib 5.6.51, for Linux (x86_64)
Copyright (c) 2000, 2021, 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/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. --ssl-mode=name SSL connection mode. -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.
--enable-cleartext-plugin
Enable/disable the clear text authentication plugin.
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                            (No default value)
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)
enable-cleartext-plugin           FALSE