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MySQL binlog_ignore_db 引數的具體使用

前言:

經過前面文章學習,我們知道 binlog 會記錄資料庫所有執行的 DDL 和 DML 語句(除了資料查詢語句select、show等)。注意預設情況下會記錄所有庫的操作,那麼如果我們有另類需求,比如說只讓某個庫記錄 binglog 或排除某個庫記錄 binlog ,是否支援此類需求呢?本篇文章我們一起來看下。

1. binlog_do_db 與 binlog_ignore_db

當資料庫例項開啟 binlog 時,我們執行 show master status 命令,會看到有 Binlog_Do_DB 與 Binlog_Ignore_DB 選項。

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000009|282838||||
+---------------+----------+--------------+------------------+-------------------+

預設情況下,這兩個選項為空,那麼這兩個引數有何作用?是否如同其字面意思一個只讓某個庫記錄 binglog 一個排除某個庫記錄 binlog 呢?筆者查閱官方文件,簡單說明下這兩個引數的作用:

  • binlog_do_db:此引數表示只記錄指定資料庫的二進位制日誌,預設全部記錄。
  • binlog_ignore_db:此引數表示不記錄指定的資料庫的二進位制日誌。

這兩個引數為互斥關係,一般只選擇其一設定,只能在啟動命令列中或配置檔案中加入。指定多個數據庫要分行寫入,舉例如下:

#指定db1db2記錄binlog
[mysqld]
binlog_do_db=db1
binlog_do_db=db2

#不讓db3db4記錄binlog
[mysqld]
binlog_ignore_db=db3
binlog_ignore_db=db4

此外,這二者引數具體作用與否還與 binlog 格式有關係,在某些情況下 binlog 格式設定為 STATEMENT 或 ROW 會有不同的效果。在實際應用中 binlog_ignore_db 用途更廣泛些,比如說某個庫的資料不太重要,為了減輕伺服器寫入壓力,我們可能不讓該庫記錄 binlog 。網上也有文章說設定 binlog_ignore_db 會導致從庫同步錯誤,那麼設定該引數到底有什麼效果呢,下面我們來具體實驗下。

2. binlog_ignore_db 具體效果

首先說明下,我的測試資料庫例項是 5.7.23 社群版本,共有 testdb、logdb 兩個業務庫,我們設定 logdb 不記錄 binlog ,下面來具體實驗下:

#binlog為ROW格式

#1.不使用usedb
mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|154||logdb||
+---------------+----------+--------------+------------------+-------------------+
mysql>selectdatabase();
+------------+
|database()|
+------------+
|NULL|
+------------+
1rowinset(0.00sec)
mysql>CREATETABLEtestdb.`test_tb1`(idint,namevarchar(30))ENGINE=InnoDBDEFAULTCHARSET=utf8;
QueryOK,0rowsaffected(0.06sec)

mysql>insertintotestdb.test_tb1values(1001,'sdfde');
QueryOK,1rowaffected(0.01sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|653||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLElogdb.`log_tb1`(idint,0rowsaffected(0.05sec)

mysql>insertintologdb.log_tb1values(1001,1rowaffected(0.00sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|883||logdb||
+---------------+----------+--------------+------------------+-------------------+
mysql>insertintologdb.log_tb1values(1002,'sdsdfde');
QueryOK,1rowaffected(0.01sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|883||logdb||
+---------------+----------+--------------+------------------+-------------------+

mysql>altertablelogdb.log_tb1addcolumnc3varchar(20);
QueryOK,0rowsaffected(0.12sec)
Records:0Duplicates:0Warnings:0

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1070||logdb||
+---------------+----------+--------------+------------------+-------------------+
#結論:其他庫記錄正常 logdb庫會記錄DDL 不記錄DML

#2.使用usetestdb跨庫
mysql>usetestdb;
Readingtableinformationforcompletionoftableandcolumnnames
Youcanturnoffthisfeaturetogetaquickerstartupwith-A

Databasechanged
mysql>selectdatabase();
+------------+
|database()|
+------------+
|testdb|
+------------+
1rowinset(0.00sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1070||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLE`test_tb2`(idint,0rowsaffected(0.05sec)

mysql>insertintotest_tb2values(1001,1rowaffected(0.04sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1574||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLElogdb.`log_tb2`(idint,0rowsaffected(0.05sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1810||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>insertintologdb.log_tb2values(1001,1rowaffected(0.01sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1810||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)
#結論:同樣logdb庫會記錄DDL 不記錄DML 

#3.使用uselogdb跨庫
mysql>uselogdb;
Readingtableinformationforcompletionoftableandcolumnnames
Youcanturnoffthisfeaturetogetaquickerstartupwith-A

Databasechanged
mysql>selectdatabase();
+------------+
|database()|
+------------+
|logdb|
+------------+
1rowinset(0.00sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1810||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLEtestdb.`test_tb3`(idint,0rowsaffected(0.23sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|1810||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>insertintotestdb.test_tb3values(1001,1rowaffected(0.02sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2081||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLE`log_tb3`(idint,0rowsaffected(0.05sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2081||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>insertintolog_tb3values(1001,1rowaffected(0.02sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2081||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)
#結論:logdb都不記錄同時不記錄其他庫的DDL

#4.每次操作都進入此庫不跨庫
mysql>usetestdb;
Readingtableinformationforcompletionoftableandcolumnnames
Youcanturnoffthisfeaturetogetaquickerstartupwith-A

Databasechanged
mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2081||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>CREATETABLE`test_tb4`(idint,0rowsaffected(0.05sec)

mysql>insertintotest_tb4values(1001,1rowaffected(0.01sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2585||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>uselogdb;
Readingtableinformationforcompletionoftableandcolumnnames
Youcanturnoffthisfeaturetogetaquickerstartupwith-A

Databasechanged
mysql>CREATETABLE`log_tb4`(idint,0rowsaffected(0.04sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2585||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)

mysql>insertintolog_tb4values(1001,1rowaffected(0.01sec)

mysql>showmasterstatus;
+---------------+----------+--------------+------------------+-------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|Executed_Gtid_Set|
+---------------+----------+--------------+------------------+-------------------+
|binlog.000011|2585||logdb||
+---------------+----------+--------------+------------------+-------------------+
1rowinset(0.00sec)
#結論:其他庫全部記錄 logdb全不記錄

同樣的,將 binlog 格式設定為 STATEMENT ,再次進行測試,這裡不再贅述測試過程,總結下 STATEMENT 格式下的實驗結果:

  • 未選擇任何資料庫進行操作,所有都會記錄。
  • 選擇testdb,對testdb和logdb分別進行操作,所有庫都會記錄。
  • 選擇logdb,對testdb和logdb分別進行操作,所有庫都不會記錄。
  • 選擇某個庫並只對當前庫進行操作,則記錄正常,不會記錄logdb。

看了這麼多實驗資料,你是否眼花繚亂了呢,下面我們以思維導圖的形式總結如下:

MySQL binlog_ignore_db 引數的具體使用

這麼看來 binlog_ignore_db 引數的效果確實和諸多因素有關,特別是有從庫的情況下,主庫要特別小心使用此引數,很容易產生主從同步錯誤。不過,按照嚴格標準只對當前資料庫進行操作,則不會產生問題。這也告訴我們要嚴格按照標準來,只賦予業務賬號某個單庫的許可權,也能避免各種問題發生。

總結:

不清楚各位讀者是否對這種介紹引數的文章感興趣呢?可能這些是資料庫運維人員比較關注的吧。本篇文章主要介紹關於 binlog 的 binlog_ignore_db 引數的具體作用,可能本篇文章實驗環境還不夠考慮周全,有興趣的同學可以參考下官方文件,有助於對該引數有更深入的瞭解。

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