"mysql" plugin
The "mysql" plugin connects to an
MySQL-database
and issues a SHOW
STATUS-command
periodically. The command returns the server
status variables many of which are
collected. The plugin has successfully been
tested with the MySQL-versions 4
and 5.
This page has the following sections:
Command statistics
This RRD-file contains the number of issues per second for various SQL-commands. Counters that are zero (i. e. the command has never been issued since server startup) are ignored, since graphing all commands would create a lot of very uninteresting RRD-files which just eat up space..
Filename
Data sources
value(counter, min 0)- Issues per second for this command.
Example graph
Handler statistics
The handler statistics gathered basically refer to the operations that can be done on tables or table-rows. This graph can give you some information if you indexes are okay or if you need some work there. Read the "server status variables"-documentation, though it leaves you with lots of questions. At least it left me wondering what was actually going on.. ;)
Filename
Data sources
value(counter, min 0)- Issues per second for this handler.
Example graph
Query-cache statistics
MySQL will try to cache queries (i. e.
SELECT-statements). Information
about the query cache can be found
on MySQL's homepage.
Filename
Data sources
hits(counter, min 0)- Number of queries that were found in the cache.
inserts(counter, min 0)- Number of queries that were added to the cache.
not_cached(counter, min 0)- Number of queries that could not be cached.
lowmem_prunes(counter, min 0)- Number of queries that were deleted from the cache due to low memory.
queries_in_cache(counter, min 0)- Number of queries currently in the cache.
Example graph
Thread statistics
Information about the threads of the MySQL process(es).
Filename
Data sources
running(gauge, min 0)- Number of threads that are actually doing some work.
connected(gauge, min 0)- Number of threads waiting on established connections.
cached(gauge, min 0)- Number of threads in the thread cache. Whatever that means.
created(counter, min 0)- Number of threads created. The values can hardly be right.
Example graph
Dependencies
- The MySQL library.