Subject Re: [firebird-support] FB SS 2.5 SMP - clarification
Author Michael Ludwig
unordained schrieb am 20.04.2012 um 15:49 (-0500):

> Background:
> I'm currently contemplating switching from 2.1 CS to 2.1 SS on an SMP
> server, because of the non-shared-cache cost. The DB is metadata-heavy
> (but usually quite CPU-friendly, that's not an issue), and a lot of
> queries currently seem to block just at prepare time, as it loads 200
> megs of metadata (it always seems like a lot to me -- does it prepare
> BLR "inline"'d, multiplying the size of the code in RAM?) into RAM for
> that instance.

So, "BLR stands for Binary Language Representation", I didn't know this.

Is metadata the same as BLR? All definitions of tables, permissions,
procedures, etc?

How do you measure metadata volume? I mean, when looking at taskmgr or
ps/top/vmstat, how do you know that the memory consumption is due to
metadata and not buffers allocated for this or that?

> They're connection-pooled (tomcat) but DBCP often rotates out the
> "already cached" db instances in favor of the "small but dumb" ones,
> and then another user soon pays the cost again, which pains me
> greatly. It can take 3-4 seconds to load that much metadata; also,
> that accumulates quickly in a multi-user setting, and I start having
> swap-space issues, which aren't helping my i/o costs. (I have a lot of
> tables, triggers, and dependencies between them: a single insert can,
> in theory, have a ripple effect across dozens of tables, and I
> understand why FB has to prepare for it.) I'm hoping SS can help me
> pay that cost nearer to once per boot and, overall, perform better.

Interesting report. Thanks.