sybperl-l Archive

From: michael dot x dot peppler at jpmchase dot com
Subject: RE: Is there a performance advantage to using placeholders with Sybase?
Date: Jan 8 2008 10:29AM

You can use placeholders with a stored proc execution. This will tell 
DBD::Sybase to execute an RPC call rather than a SQL Language call to 
execute the proc. This is slightly faster (no SQL parse), but because 
DBD::Sybase does not know the type of all the parameters (it could look it 
up, but that's also an overhead) you have to specify the datatype of the 
parameters when you bind.

I haven't checked execute_array vs execute - off-hand I don't think that 
there would be any real performance advantage.

For emulating placeholder behavior in more complex T-SQL code - sure it 
could be done, but it would mean a lot more syntax analysis in the 
prepare() code itself, to determine if the SQL buffer is a single command 
or not, and triggering the native placeholder handling vs. emulation 
depending on the situation.

Michael





"Ed Avis"  
08.01.2008 10:59

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, 
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Subject
RE: Is there a performance advantage to using placeholders with Sybase?






Michael Peppler wrote:

>Yes, OpenClient has an API that creates a "prepared" statement 
>(actually known as a light-weight stored procedure) for you, 

Suppose the query you want to prepare is itself to run a stored procedure.

    exec my_proc ?, ?, ?

Is there any performance advantage to using a prepared statement here?

With DBD::Sybase, does execute_array() have any performance advantage over 
calling execute() repeatedly?

>Another limitation is that placeholders can only be used for 
>single statement SQL batches (i.e. a single 
>SELECT/INSERT/UPDATE/DELETE statement). You can't use 
>placeholders if you want to submit a statement that includes 
>other T-SQL code (flow control, conditionals, while loops, etc). 

Hmm, couldn't DBD::Sybase work around this with a 'fake placeholders' 
feature?  I think some other DBDs have that because their DBMSes don't 
support placeholders at all.

-- 
Ed Avis  

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