Re: Priority table or Cache table

On 20 Feb 2014, at 01:38, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com> writes:
>> I want to propose a new feature called "priority table" or "cache table".
>> This is same as regular table except the pages of these tables are having
>> high priority than normal tables. These tables are very useful, where a
>> faster query processing on some particular tables is expected.
>
> Why exactly does the existing LRU behavior of shared buffers not do
> what you need?
>
> I am really dubious that letting DBAs manage buffers is going to be
> an improvement over automatic management.
>
> regards, tom lane

the reason for a feature like that is to define an area of the application which needs more predictable runtime behaviour.
not all tables are created equals in term of importance.

example: user authentication should always be supersonic fast while some reporting tables might gladly be forgotten even if they happened to be in use recently.

i am not saying that we should have this feature.
however, there are definitely use cases which would justify some more control here.
otherwise people will fall back and use dirty tricks sucks as “SELECT count(*)” or so to emulate what we got here.

many thanks,

hans

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