| Subject | Re: [ib-support] Data Caching by IB |
|---|---|
| Author | Jason Chapman (JAC2) |
| Post date | 2002-08-30T12:56:41Z |
Sorry, no simple answers.
It depends how many pages of data were required to get the results. If the
plan was natural, and the results were sorted then the every data page of
the table may be in memory.
The engine AFAIK goes:
1) How will I execute the query
2) Get first rows of data required by the remote interface
Gets data until it has enough data.
so
select * from table order by PK
or select * from table
may only hit a few pages and therefore cache a few pages
but
select * from table where someNonIndexedField = 20
will require the server to fetch (potentially) a lot of the data prior to
return
or
select * from table order by someNonIndexedField
will require the server to fetch ALL data prior to return
Jason Chapman
JAC2 Consultancy
Training - Development - Consultancy
Delphi, InterBase, Firebird, OOAD, Development lifecycle assistance,
Troubleshooting projects, QA.....
www: When I get round to it....
Mob: (+44) 07966 211 959 (preferred)
Tel: (+44) 01928 751088
will require the server to fetch all of the data prior to return
""Jack Cane"" <jwcane@...> wrote in message
news:NBBBJIAMCLJIMAIEKAKEGEEMFNAA.jwcane@......
It depends how many pages of data were required to get the results. If the
plan was natural, and the results were sorted then the every data page of
the table may be in memory.
The engine AFAIK goes:
1) How will I execute the query
2) Get first rows of data required by the remote interface
Gets data until it has enough data.
so
select * from table order by PK
or select * from table
may only hit a few pages and therefore cache a few pages
but
select * from table where someNonIndexedField = 20
will require the server to fetch (potentially) a lot of the data prior to
return
or
select * from table order by someNonIndexedField
will require the server to fetch ALL data prior to return
Jason Chapman
JAC2 Consultancy
Training - Development - Consultancy
Delphi, InterBase, Firebird, OOAD, Development lifecycle assistance,
Troubleshooting projects, QA.....
www: When I get round to it....
Mob: (+44) 07966 211 959 (preferred)
Tel: (+44) 01928 751088
will require the server to fetch all of the data prior to return
""Jack Cane"" <jwcane@...> wrote in message
news:NBBBJIAMCLJIMAIEKAKEGEEMFNAA.jwcane@......
> Jason,data
>
> Thanks. Now, in order to be perfectly clear, let me pose an example. If I
> ask for a Web page that sends back, for example, an html table based on a
> data grid that is limited to 8 rows of data from a 500-row table, what
> are cached, the 8 rows, or the entire table?of
>
> jwc
> -----Original Message-----
> From: news@... [mailto:news@...]On Behalf Of Jason
> Chapman (JAC2)
> Sent: Sunday, August 25, 2002 6:41 AM
> To: ib-support@yahoogroups.com
> Subject: Re: [ib-support] Data Caching by IB
>
>
> MSSQL latest versions have a feature to cache "results" and re-uses them
> if
> it can, e.g. multiple users posting the same SQL.
>
> IB / FB does not cache results ever. It does however cache the raw data
> that was used to generate the results, i.e. data pages from disk. The
> obviously cache's disk reads also.
>
> I don't think you should change IB/FB's cache settings as this may
> adversely
> affect normal operation.
>
> When we do testing we have a ground zero state, it may be a fresh boot
> the OS, it may be a a restart of the FB service, depends on what we arethat
> doing.
>
> Jason Chapman
> JAC2 Consultancy
>
> Training - Development - Consultancy
> Delphi, InterBase, Firebird, OOAD, Development lifecycle assistance,
> Troubleshooting projects, QA.....
> www: When I get round to it....
> Mob: (+44) 07966 211 959 (preferred)
> Tel: (+44) 01928 751088
>
>
>
> ""Jack Cane"" <jwcane@...> wrote in message
> news:NBBBJIAMCLJIMAIEKAKEOECKFNAA.jwcane@......
> > Yes, exactly. result set caching is what I meant.
> >
> > So, now it appears to me that IB does not do resultset caching. Is
> > correct?
> >
> > jwc
> > -----Original Message-----
> > From: Kenneth Foo [mailto:kenneth@...]
> > Sent: Friday, August 23, 2002 10:18 PM
> > To: ib-support@yahoogroups.com
> > Subject: Re: [ib-support] Data Caching by IB
> >
> >
> > I think Jack was referring to resultset caching,
> > a feature present in the newer MySQL.
> > Read somewhere about db benchmarks
> > where MySQL performance "rivalled" Oracle simply
> > because of this feature...
> >
> >
> >
> >
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