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Displaying posts with tag: tables (reset)
What is MySQL Partitioning?

In this blog, we’ll quickly look at MySQL partitioning.

Partitioning is a way in which a database (MySQL in this case) splits its actual data down into separate tables, but still get treated as a single table by the SQL layer.

When partitioning, it’s a good idea to find a natural partition key. You want to ensure that table lookups go to the correct partition or group of partitions. This means that all SELECT, UPDATE, DELETE should include that column in the WHERE clause. Otherwise, the storage engine does a scatter-gather, and queries ALL partitions in a UNION that is not concurrent.

Generally, you must add the partition key into the primary key along with the auto increment, i.e., PRIMARY KEY (part_id,id). If you …

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ProxySQL Admin Interface Is Not Your Typical MySQL Server!

In this blog post, I’ll look at how ProxySQL Admin behaves in some unusual and unexpected ways from a MySQL perspective.

ProxySQL allows you to connect to its admin interface using the MySQL protocol and use familiar tools, like the MySQL command line client, to manage its configuration as a set of configuration tables. This ability may trick you into thinking that you’re working with a stripped-down MySQL server – and expect it to behave like MySQL. 

It would be a mistake to think this! In fact, ProxySQL embeds the SQLite database to store its configuration. As such, it behaves much closer to SQLite!

Below, I’ll show you a few things that confused me at first. All of these are as of ProxySQL 1.3.6 (in case behavior changes in the future).

Fake support for Use command

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Using Percona XtraBackup on a MySQL Instance with a Large Number of Tables

In this blog post, we’ll find out how to use Percona XtraBackup on a MySQL instance with a large number of tables.

As of Percona Xtrabackup 2.4.5, you are required to have enough open files to open every single InnoDB tablespace in the instance you’re trying to back up. So if you’re running innodb_file_per_table=1, and have a large number of tables, you’re very likely to see Percona XtraBackup fail with the following error message:

InnoDB: Operating system error number 24 in a file operation.
InnoDB: Error number 24 means 'Too many open files'
InnoDB: Some operating system error numbers are described at http://dev.mysql.com/doc/refman/5.7/en/operating-system-error-codes.html
InnoDB: File ./sbtest/sbtest132841.ibd: 'open' returned OS error 124. Cannot continue operation
InnoDB: Cannot …
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Backup and Restore of Encrypted Innodb Tables


Distributing innodb tables made simpler!

With the support for cloud backups in MEB, distributing innodb tables across multiple MySQL instances has become easier.

1. Backup - take a cloud(Amazon S3) backup of the tables to be shared using the --use-tts=with-full-locking option.

./mysqlbackup \
--host=localhost --user=mysqluser --protocol=TCP --port=3306 \
--cloud-service=s3 --cloud-aws-region=us-east-1 \
--cloud-bucket=mebbackup –cloud-object-key=items.img \
--cloud-access-key-id=<access-key> --cloud-secret-access-key=<secret-key> \
--include-tables=^mycompany\.items.* --use-tts=with-full-locking \
--backup-dir=/tmp/bkups/backupdir --compress --backup-image=- …

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Regarding MySQL 5.6 temporary tables format

default_tmp_storage_engine variable was introduced in 5.6.3, allowing the configuration of the default engine for temporary tables. This seems to be in the direction, as I commented before, of making MyISAM an optional engine. In 5.7, a separate tablespace is being created to hold those tables in order to reduce its performance penalty (those tables do not need to be redone if the server crashes, so extra writes are avoided).

However, I have seen many people assuming that because default_tmp_storage_engine has the value “InnoDB”, all temporary tables are created in InnoDB format in 5.6. This is not true: first, because implicit temporary tables are still being created in memory using …

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Automatic Logging of Table Data Changes and Creation of Backups via a Stored Procedure

Permalink: http://bit.ly/1rNFRsO



The stripped down stored procedure shown below will accept any Data Manipulation Language statement as its parameter and automatically log the statement and create table backup copies before the statement is executed. The logging functionality is similar to MySQL's binary log but exclusive to DML statements and is useful for table data recovery operations, such as undoing the last table data change or to revert databases back to a certain point in time. All this is done exclusively using stored routines (procedures and functions).

Its assumed that the databases and tables that will be used are already formed to specific business requirements since DDL statements will not be logged by the stored procedure. Though logging of table data changes can also be achieved using triggers, it is not practical to alter each and …

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pstop – a top-like program for MySQL (based on performance_schema)

I have been working with MySQL for some time and it has changed significantly from what I was using in 5.0 to what we have now in 5.6. One of the biggest handicap we’ve had in the past is to not be able to see what MySQL is doing or why. MySQL 5.5 introduced us … Continue reading pstop – a top-like program for MySQL (based on performance_schema)

InnoDB Temporary Tables just got faster

It all started with a goal to make InnoDB temporary tables more effective. Temporary table semantics are blessed with some important characteristics that can help us simplify lot of operations.

  • Temporary tables are not visible across connections
  • Temporary tables lifetime is limited to connection lifetime (unless user explicitly drops it).

What does this means in to InnoDB ?

  • REDO logging can be avoided for temporary tables and related objects since temporary tables do not survive a shutdown or crash.
  • Temporary table definitions can be maintained in-memory without persisting to the disk.
  • Locking constraints can be relaxed since only one client can see these tables.
  • Change buffering can be avoided since the majority of temporary tables are short-lived.

In order to implement these changes in InnoDB we took a bit different approach:

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MySQL and InnoDB comments…

Hello everyone, here we go for a new blog post and now treating about InnoDB inside MySQL 5.5 and as you should now, this new version uses InnoDB Plugin version 1.1 which one has a lot of new adjustable resources. What most caught my attention was the impressed way that users could adjust it to have [...]

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