MariaDB/Features

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The features that are discussed in this page have been developed for MariaDB and probably are not present in MySQL.

Pool of threads[edit]

Table elimination[edit]

Microseconds precision[edit]

SHOW PROCESSLIST, INFORMATION_SCHEMA.PROCESSLIST and the Slow Log now have a microsecond precision.

A microsecond is a unit of time equal to one millionth (10-6) of a second.

SHOW PROCESSLIST[edit]

In MariaDB, an extra column `TIME_MS` has been added to the INFORMATION_SCHEMA.PROCESSLIST table, as well as to the output of SHOW FULL PROCESSLIST. This column shows the same information as the column `TIME`, but in units of milliseconds with microsecond precision (the unit and precision of the `TIME` column is one second).

The value displayed in the `TIME` and `TIME_MS` columns is the period of time that the given thread has been in its current state. Thus it can be used to check for example how long a thread has been executing the current query, or for how long it has been idle.

In MariaDB the `TIME` column and the `TIME_MS` column are not affected by any setting of @TIMESTAMP. This means that it can be reliably used also for threads that change @TIMESTAMP (such as the replication SQL thread).

The `TIME` column of SHOW FULL PROCESSLIST and INFORMATION_SCHEMA.PROCESSLIST can not be used to determine if a slave is lagging behind. For this, use instead the Seconds_Behind_Master column in the output of SHOW SLAVE STATUS.

The addition of the TIME_MS column is based on the microsec_process patch, developed by Percona.

Slow Log[edit]

The Slow Log includes details of execution plan and microsecond-precision resolution.

This addition is based on the microslow patch from Percona.

Performance[edit]

MariaDB's code has several optimizations which have been made after the fork has been launched.

Some speed enhancements are:

  • CHECKSUM TABLE is faster;
  • performance improvements for common cases of character set conversion;
  • test suite speedups.

The list is not complete.