My first consideration with regards to bind variables is to consider the
cost of parsing the query. After all the benefit of bind variables (or at
least a major one) is to reduce the number of parses required. If the
query is going to be executed so rarely that the parse cost (a fraction of
a second typically) isn't significant then there appears to be little
benefit.
I think bind variables are most useful in OTLP where the same query gets
fired again and again (especially when you have hundreds of client
connections). At the other extreme (a batch query executed once per day)
they aren't required. Therefore my approach tends to be "is the query
going to be executed very frequently - if so then look at using bind
variables on the values that will change".
Regards,
Mark.
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<[EMAIL PROTECTED]>
Sent by: cc:
[EMAIL PROTECTED] Subject: RE: Oracle position on hints
om
11/03/2003
05:09
Please respond
to ORACLE-L
Well, I wouldn't say you should *always* use bind variables.
Many situations in a database warehouse preclude that.
Potentially long running queries may need to have literals
to help the CBO make the right choice.
Star transforms don't work with bind variables, and histograms
can't be used with bind variables.
Jared
"Nicoll, Iain" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
03/08/2003 06:23 AM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
cc:
Subject: RE: Oracle position on hints
Given the attitude of most dba's that you should always use bind variables
where possible I can't see how you'd cope with skewed data without them.
Most developers should know a databases's data better than the optimiser
and
certainly when building queries it's always worthwhile seeing where data
is
being most effectively filtered.
There are lots of mature systems out there where the data characteristics
are unlikely to change much and for most in-house developers you're never
going to have to think about portability but always about performance.
Iain Nicoll
-----Original Message-----
Sent: 07 March 2003 16:04
To: Multiple recipients of list ORACLE-L
Hi,
Does Oracle have an official position on hints ?
Will they go away as the optimiser is becoming bettre or they are there to
stay ?
TIA
Stephane Paquette
Administrateur de bases de donnees
Database Administrator
Standard Life
www.standardlife.ca
Tél. (514) 925-7187
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]
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