Hello Ann and all

Thank you so much for this interesting information. I have tried to set the transaction level within an SQL statement and a stored procedure.

I just get Dynamic SQL error when I run this. What am I doing wrong.

SET TRANSACTION READ ONLY;
select * from "Booking"

--- In firebird-support@yahoogroups.com, Ann Harrison <aharrison@...> wrote:
>
> Doug Chamberlin <chamberlin.doug@...> wrote:
>
> >
> > Two things come immediately to mind:
> >
> > 1) Everything gets read and written to the file system in blocks. So
> > even if you just update one byte in one record at least one whole block
> > is read and written. Of course, that is subject to caching, etc, but if
> > the monitor you are watching is counting bytes you will see lots more
> > moving around than you might have expected.
> >
>
> Correct. The minimal write block size is a page, so if you're using 16K
> pages, changing someones age from 39 to 40 will cause a 16K write.
>
>
> >
> > 2) Everything takes place in a transaction and the server needs to track
> > transactions so there is housekeeping done to record when transactions
> > start and stop. This applies to simple transactions that just read data
> > as well as those that change data. So consider an additional block or
> > two being read and written for each transaction. (For example, there is
> > a Transaction Inventory Page which is the most frequently read and
> > written block in the whole database.)
> >
>
> Close, but not entirely right. READ_ONLY READ_COMMITTED transactions don't
> get unique transaction identifiers and don't cause writes to the header and
> Transaction Inventory Pages (tip). And although the last tip is pretty
> busy, the busiest page in the database is the header page, which changes
> once for every transaction that's not RO/RC and once for every new
> connection.
>
> >
> > I'm sure Ann and others will add more to this.
> >
>
> Correct.
>
> Good luck,
>
> Ann
>
>
> [Non-text portions of this message have been removed]
>