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Re: MySQL Cluster 'Auto Commit'
Posted by: Mikael Ronström
Date: February 25, 2005 08:11AM

Wai Boon Ng wrote:
> Hi All,
>
> I had setup a MySQL Cluster based on the
> recommended and std pratice, which is 1 management
> console and 2 NDB nodes.
>
> I wonder other than putting the cron job to run
> the backup every X minutes/hours to force data in
> the memory to save to the disk.
>

There are a number of parameters to play around with.

1) By default MySQL Cluster performs checkpoints of main memory data to
disk even without using the backup command. The backup command is more
to be able to restore data from a certain time or to move data to another cluster.
Checkpointing for recovery is done automatically by MySQL Cluster. This happens
at intervals which you can influence by setting the config variable
TimeBetweenLocalCheckpoints (see the manual for info on how to set it).
Default is to start a new local checkpoint after writing 4 MB of updates. (=20 => 2**20 Words)

2) MySQL Cluster creates log records of each transaction and when these have been
forced to disk the transaction is safe on disk. The period between those force to disk is
set by the config variable
TimeBetweenGlobalCheckpoints (default a few seconds)

Rgrds Mikael

> What other think i can do to make MySql TO COMMIT
> ?

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