Re: PostgreSQL, MySQL, etc., was Re: PostgreSQL is much

A long time ago, in a galaxy far, far away, Randolf Richardson <rr(at)8x(dot)ca> wrote:
> [sNip]
>>> the difference is that with mysql, nothing pushes the table out of
>>> memory; it always stays in memory. in postgresql, a big query on
>>> another tables, or perhaps a vacuum, or other highly active
>>> applications on the same server can cause the small tables to be
>>> pushed out of memory. both approches have positives and
>>> negatives, and in many cases you would probably notice no
>>> differance
>>
>> If this is a small heavily used table, 7.5 with the new ARC buffer
>> management policy should do much better. Even better, the table
>> does not actually need to be small: the heavily used portion will
>> stay in memory where it can be very fast, and the rest will be just
>> wait its turn on disk.
>
> Is this a configurable option by any chance? If not, then
> perhaps it should be on a per-table, per-index (etc.) basis.

It is a MUCH BETTER thing to have policies that don't require
configuration effort.

One of the characteristic problems with Oracle is that you have
immense numbers of "knobs" to tune. You can get it to work "just
right" if you throw a large enough horde of DBAs at it.

In the case of the ARC policy, what Jan is trying to do is to come up
with a strategy that is an improvement irrespective of the
characteristics of the table. If that works out as hoped for, there
will be no need to "configure" anything in order to take advantage of
it.

You'd find your applications running faster simply by installing a 7.5
server; no need to configure anything. It's like getting Pentium chip
with improved execution strategies; you don't have to recompile
anything (the way IA-64 mandates it); you just install the app on the
new box and watch it speed up.
--
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