List of new my.cnf variables

Asked by Olivier Doucet on 2010-04-29

I could not find any file/URL with a complete overview of all variables added to my.cnf in the facebook mysql version.
For example, "innodb_flush_neighbors_on_checkpoint"
Such a page would be useful with just a few explanations.

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Last query:
2010-05-03
Last reply:
2010-05-05
Mark Callaghan (mdcallag) said : #1

Yes, it would be useful. If you start a wiki page by diffing patched mysqld with unpatched mysqld and list all of the variables here then will update some of them. Most of the my.cnf variables that we added have reasonable comments that are a good by the standards of my.cnf variables.

Olivier Doucet (odoucet) said : #2

Hi,
I can start the page ;)
Which wiki are you talking about by the way ?

Here is the list of vars I found using fgrep and diff :

adaptive_hash_latch_cache
compression_level
deadlock_detect
flush_neighbors_on_checkpoint
prepare_commit_mutex
read_ahead_linear
retry_io_on_error
thread_lifo

I will complete them with the prototype and comment already in source code as soon as you show me where to create such a page ;)

Mark Callaghan (mdcallag) said : #3

launchpad doesn't have a wiki (yet)
I will soon publish elsewhere release notes that I have written

On Mon, May 3, 2010 at 8:02 AM, Olivier Doucet
<email address hidden> wrote:
> Question #108751 on MySQLAtFacebook changed:
> https://answers.launchpad.net/mysqlatfacebook/+question/108751
>
> Olivier Doucet gave more information on the question:
> Hi,
> I can start the page ;)
> Which wiki are you talking about by the way ?
>
> Here is the list of vars I found using fgrep and diff :
>
> adaptive_hash_latch_cache
> compression_level
> deadlock_detect
> flush_neighbors_on_checkpoint
> prepare_commit_mutex
> read_ahead_linear
> retry_io_on_error
> thread_lifo
>
> I will complete them with the prototype and comment already in source
> code as soon as you show me where to create such a page ;)
>
> --
> You received this question notification because you are a direct
> subscriber of the question.
>

--
Mark Callaghan
<email address hidden>

Olivier Doucet (odoucet) said : #4

Fine! Here are already new vars and description extracted from source :

adaptive_hash_latch_cache = TRUE|FALSE (default true)
When TRUE allow the InnoDB adaptive hash index latch (rw-lock) be cached across calls to InnoDB functions. This is only done when locked in read mode.

compression_level = INT (0 to 9. default: 6)
Compression level used for compressed row format. 0 is no compression (only for testing), 1 is fastest, 9 is best compression, default is 6.

deadlock_detect = TRUE|FALSE (default: true)
Detect deadlocks when locks are acquired. Without this the row lock wait timeout resolves deadlock.

flush_neighbors_on_checkpoint = TRUE|FALSE (default: true)
Flush (write) dirty neighbor pages within an extent when a dirty page is to be written during checkpoint. This is enabled by default.

prepare_commit_mutex = TRUE|FALSE (default: true)
Lock the prepare_commit_mutex before writing to binlog

read_ahead_linear = TRUE|FALSE (default: true)
Enable use of readahead (prefetch)

retry_io_on_error = TRUE|FALSE (default: false)
Retry on I/O on EIO

thread_lifo = TRUE|FALSE (default: false)
"Enables the LIFO scheduling policy for thread_concurrency in addition to the FIFO scheduling that has always been used.