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Showing entries 1 to 10 of 26 10 Older Entries

Displaying posts with tag: mysql administration (reset)

Using GDB, investigating segmentation fault in MySQL
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In previous article, we have covered some errors and issues with using MySQL in “disk full” environment. Where there was no space left on device.(See here: Testing Disk Full Conditions)
Today’s scenario is -> Starting MySQL with GTID/binary log enabled, in 0 space left Linux(CentOS 6.5) environment.

If you hit a bug or problem, general rule for helping community to fix it is to provide as much information as possible. Especially useful is to give gdb output from coredump. To get coredump you can read this wonderful article …


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Testing “disk full” conditions in MySQL
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How MySQL will act if there is no space left on hard disk?
To answer this question, let’s test it:

Our first test is with MySQL 5.6.24-debug with disabled binary log:
Trying to import huge dump, after while it says table is full:

Query OK, 12725 rows affected (2.46 sec)
Records: 12725  Duplicates: 0  Warnings: 0

Query OK, 12724 rows affected (2.40 sec)
Records: 12724  Duplicates: 0  Warnings: 0

Query OK, 12726 rows affected (2.53 sec)
Records: 12726  Duplicates: 0  Warnings: 0

ERROR 1114 (HY000): The table 'sales' is full
ERROR 1114 (HY000): The table 'sales' is full
ERROR 1114 (HY000): The table 'sales' is full

In error log you will see …



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Playing with count(*) optimizer work
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Article about bug report #68814 related to testing count(*) explain plan.

Or sales table huge enough to play with.

mysql> select count(*) from sales;
+----------+
| count(*) |
+----------+
|  2500003 |
+----------+
1 row in set (0.56 sec)

First with regular count(*) without where clause:

mysql> explain select count(*) from sales\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: sales
         type: index
possible_keys: NULL
          key: sales_cust_idx
      key_len: 4
          ref: NULL
         rows: …
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MySQL-AutoXtrabackup command line tool for using Percona Xtrabackup
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Want to introduce our MySQL-AutoXtraBackup command line tool, using Percona Xtrabackup in core. Looking for contributor

Add Patch to MySQL source code in Linux
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Due to reported BUG report(BUG 73365) i am testing full disk error conditions with MySQL 5.6.19-debug-log.

There were some interesting error messages in error log:

2014-07-23 08:09:59 7f44500f0700 InnoDB: Error: Write to file ./xxx/news.ibd failed at offset 218103808.
InnoDB: 1048576 bytes should have been written, only -1 were written.
InnoDB: Operating system error number 28.
InnoDB: Check that your OS and file system support files of this size.
InnoDB: Check also that the disk is not full or a disk quota exceeded.
InnoDB: Error number 28 means 'No space left on device'.

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Change binary log and relay log location to /home? SELinux issue
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Recently in my slave server there was a full disk error because of the huge size of binary logs.Which is lead to critical error and BUG report which is still stays as open:

http://bugs.mysql.com/bug.php?id=72437

So the issue was a partition problem which in partitioning stage haven’t been specified for “/” (root) filesystem. But in “/home” there were left enough space.
The quick decision was to change binary and relay log location(path) to “/home”.
But there was a great challenge to get real working slave again.

Now we will explore all steps …



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Copying Tablespaces to Another Server (Transportable Tablespaces)
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If you want take several actions on tables? It is really very exciting

Install MySQL from source with debugging option in Linux
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Dear all, our today’s topic is about finding out the cause of MySQL crash and in depth examining issue for BUG reporting.
So what is exact mean of this article?
While i reported BUGs for MySQL, developers(experts) every time ask for a core dump (with gdb) and full stack-trace. Yeap they are right, finding an issue is only one step. You must also provide all necessary information to MySQL developers if you really interested in fixing bugs in open source. You have to help to find the core of problem.
For this purpose you must have a DEBUG MySQL edition on your hand to generate core dump and to see full stack-trace. Yes as you think, we will install …


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Activate SSL connection in MySQL
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Secure connection? Today we will explore an interesting task about activating and using SSL connection in MySQL.
We will provide all necessary scripts and commands to re-play all steps.

So assume that we have CentOS 6.5 with OpenSSL and MySQL already installed:

[root@linuxsrv3 ~]# mysql --version
mysql  Ver 14.14 Distrib 5.6.17, for Linux (x86_64) using  EditLine wrapper

[root@linuxsrv3 ~]# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.6.17-log MySQL Community Server (GPL)

[root@linuxsrv3 ~]# openssl version
OpenSSL 1.0.1e-fips 11 Feb 2013

[root@linuxsrv3 ~]# rpm -qf …

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Activate validate_password Plugin
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Recently i encounter an uprising among PHP Developers that , they must write a script additionally checking the strength of MySQL user password at creation time.
So, just for note that there is ready to use plugin in MySQL named: validate_password.so

The file location is default in plugin_dir in Linux:

mysql> select @@plugin_dir;
+--------------------------+
| @@plugin_dir             |
+--------------------------+
| /usr/lib64/mysql/plugin/ |
+--------------------------+
1 row in set (0,00 sec)

List this directory:

[root@linuxsrv3 plugin]# ls
adt_null.so     auth_test_plugin.so  innodb_engine.so      mypluglib.so …

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Showing entries 1 to 10 of 26 10 Older Entries

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