Re: remove useless ccache searching

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Andy Colson <andy(at)squeakycode(dot)net>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: remove useless ccache searching
Date: 2011-09-05 18:42:31
Message-ID: CAFj8pRC33hLzd7GZr1CoH22BFb2r_3uETyibOzBguLqpSQPNWw@mail.gmail.com
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Hello

2011/9/5 Andy Colson <andy(at)squeakycode(dot)net>:
> This patch:
>
> https://commitfest.postgresql.org/action/patch_view?id=597
>
> caches the cache because, I guess, the cache is slow.
>
> Simon asked, "What is making the first cache so slow?".  Pavel does not
> know, nor how to fix it, and nobody else responded.
>
> So my question is: is someone going to take a look at the cache?  Should
> this be accepted as a short term fix (cuz someone will fix the cache later),
> long term fix (cuz the cache needs to say as-is), or not at all (because
> someone will fix cache right now now)?

A idea so this patch is cache of cache is not exact

Access to array needs lot of metadata related to element type. These
metadata are statics. I can store these data when we first access a
variable with data. ccache is relative fast - hash search, but should
not be faster than just direct access to structure. This technique is
used more time in PL/pgSQL.

Regards

Pavel

>
> -Andy
>
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