Subject Re: [firebird-support] Negative impact on system performance querying monitoring tables.
Author Mark Rotteveel
On 2019-10-04 14:01, Marcelo Guimaraes mfguimaraes@...
[firebird-support] wrote:
> Hello everyone!
>
> Reading about FB performance, I hit this page:
> https://firebirdsql.org/file/documentation/reference_manuals/fblangref25-en/html/fblangref25-appx05-montables.html
>
> My surprise on the note was the warning: "In a highly loaded
> environment, collecting information via the monitoring tables could
> have a negative impact on system performance."
>
> To administer a database and monitore his health usually we need to
> query monitoring tables (dictionary views).. On FB, according to the
> doc, we have a negative impact on system performance, so how can we by
> pass that?
>
> Was this issue solved on FB 3?

The problem is inherent to the monitoring tables. If you query one
monitoring table, Firebird needs to collect and prepare a snapshot of
the data for all other monitoring tables to be able to provide a stable
and consistent view of the monitoring tables in your current
transaction. If you do this a lot, then it will need to repeatedly spend
that time, which can have an impact on performance, because the cost of
that data collection is non-zero (.

So, the problem can't really be fixed, because that data collection will
need to happen and doing the collection takes time (CPU) and memory.

Mark