[Pgpool-hackers] Invalidating relcache

[Guillaume Lelarge]

Le 15/01/2011 04:01, Tatsuo Ishii a écrit :
>>> Pgpool-II maintaines internal relation cache to caching the query
>>> result against backend. The cache scope is per session i.e. existing
>>> in pgpool child process. The cache is mainly used for inquring system
>>> catalog to know if the table is a tempory one, or rewirting timestamp
>>> for example. Problem is, if the structure of a table which is in the
>>> cache is changed by ALTER TABLE ADD COLUMN or some such, the contents
>>> of the relcache are not valid anymore.
>>>
>>> The only solution at present is, restarting pgpool or using
>>> child_life_time, not super conveninet.
>>>
>>> My idea is adding an expiration timer in the cache entry so that the
>>> cache entry is invalidated after N seconds. The N can be changed by
>>> editing pgpool.conf.
>>>
>>> Thoughts?
>>
>> Seems interesting. 0 would mean no timer I guess?
> 
> Yes, that would be appropreate and mybe the default value for backward
> compatibility sake?

Sure.


-- 
Guillaume
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