Shinguz's blog

InnoDB Flush Log at Transaction Commit

InnoDB Flush Log at Transaction Commit is set to a values != 1. This can lead to a loss of committed transactions in case of a power failure or an unclean shutdown of your database.

InnoDB Deadlock detected

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You got an InnoDB Deadlock. Please talk to your development department to fix this problem. Deadlocks are an application problem!

InnoDB Buffer Pool Instances is too small

If you are using MariaDB/MySQL 5.5 and newer you should use several InnoDB Buffer Pool Instances for performance reasons.
Some rules to size InnoDB Buffer Pool instances are:

Binlog format MIXED with filtering

Binlog format MIXED changes the binary log format (ROW or STATEMENT) depending on the queries (deterministic or not). This makes it impossible to define 100% correctly working binary log filter rules.

Flush time is set

If the variable flush_time is set to a non-zero value, all tables are closed (and flushed) every flush_time seconds to disk. This can cause unnecessary and high I/O spikes.

Table definition cache too small

The number of table definitions (SHOW CREATE TABLE<br>G) that can be stored in the table definition cache (table_definition_cache). If you have a large number of tables (
> 400) in your database instance, you should consider a larger table definition cache to increase your database throughput and decrease your query latency.
The command SELECT COUNT(*) FROM information_schema.tables; shows you how many tables and thus table definitions you have. The global status Open_table_definitions is the current amount of open table definitions.

Table open cache too small

The Table Open Cache (table_open_cache or old name table_cache) is a cache to store file handles for all threads. The actual value of cache entries can be seen with the global status of open tables (Open_tables).
Increasing table_open_cache increases the number of file descriptors (open_files_limit) that MySQL requires.
You can check whether you need to increase the Table Open Cache by checking Open_tables and Opened_tables. If the value of Opened_tables is large and you do not use FLUSH TABLES often (which just forces all tables to be closed and reopened), then you should increase the value of the table_open_cache variable.

Limitations of Galera Cluster

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If and how to use Galera Cluster for MySQL has been described already by many others…

InnoDB Flush Method has changed

The InnoDB Flush Method has changed. This can have an impact on InnoDB write Performance.

SQL search for special characters

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The following example should work for you:

CREATE TABLE spec(txt VARCHAR(255));

Controlling worldwide manufacturing plants with MySQL

A MySQL customer of FromDual has different manufacturing plants spread across the globe. They are operated by local companies. FromDuals customer wants to maintain the manufacturing receipts centralized in a MySQL database in the Head Quarter in Europe. Each manufacturing plant should only see their specific data.

Galera and tables without a Primary Key

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We finally got the results. The table does NOT have a Primary Key and/or an index on lSessionId:

Logging Galera Cluster conflicts

We typically suggest our customers to use our MySQL/Galera Cluster my.cnf configuration template to avoid MySQL configuration and performance problems.

Galera Cluster last inactive check and VMware snapshots

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From time to time we see at Galera Cluster customer engagements the following, for me scary, warning in the MySQL error log:

Rename MySQL Partition

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Before I forget it and have to search again here a short note about how to rename a MySQL Partition:

mpm run overpasses older one

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This error is NOT serious. It happens, when one MPM run overpasses an older one or when you start a second run manually.

MySQL Enterprise Incremental Backup simplified

MySQL Enterprise Backup (MEB) has the capability to make real incremental (differential and cumulative?) backups. The actual releases are quite cool and you should really look at it…

mpm/fpmmm module

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Hi burps

In Zabbix we have “hosts”. In MPM a host is either a server (DBSERVER01) or a MySQL Instance (mysqld).

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