[Pgpool-hackers] patch "Caching query results in pgpool-II"

[Masanori Yamazaki]

2011/6/14 Tatsuo Ishii <ishii at sraoss.co.jp>

> Please explain what is implemented and what is not implemented in this
> patch.
>

What is implemented in this patch are as below.
- connect to memcached.
- set RowDescription or DataRow on memcached.
- get RowDescription or DataRow on memcached by using key of md5(SELECT
convert).
- delete cache on memcached by using key of md5(SELECT convert). only
module.
- fetch and parse the fellowing data in pgpool.conf.

memory_cache_enabled
memqcache_method
memqcache_memcached_host
memqcache_memcached_port
memqcache_total_size
memqcache_expire
memqcache_maxcache
memqcache_cache_block_size

- add data to buffer before set data on memcached.
- get buffer in order to set it on memcached
- initialize buffer

I am implemented only in Simple Query case.


What is not implemented in this patch are as below.
- shmem cache.
structure of  managing table oids.
the space management map.
on memory query cache structure.

- implementation in Extended Query case.

- cache validation.
The result of SELECT using none IMMUTABLE functions is not cached.

- remove cache
If cache is full, the least recently used cache is removed.
If a table is dropped or modified, related cache data is deleted.
If a table definition is modified(ALTER TABLE), related cache data is
deleted.
If a schema or database is dropped, related cache data is deleted.


This week I am mainly implementing the shmem cache.

Regards
Masanori YAMAZAKI




> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
> > Hello, hackers
> >
> > I have implemented a function caching query on memcached.
> > I am sending the patch file and it's so nice to give me some opinions.
> >
> > Main program which I implemented is as below.
> > - Search for cache data on memcached by using md5 which converted SELECT
> > into.
> > - Set data on memcached. The key is md5 which converted  SELECT into.
> > The value is RowDescription, DataRow from Backend.
> >
> > [Modify files]
> > - pool.h
> > - child.c
> > - pool_config.l
> > - pool_config.h
> > - pool_config.c
> > - pool_system.c
> > - pool_proto_modules.c
> > - pool_process_query.c
> >
> > [New File]
> > - pool_memqcache.c
> >
> >
> > --
> > Regards
> > Masanori YAMAZAKI
>
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