RE: Reduce parsing

Hi Tracy,

The 'parse calls' statistic is count of how many times the client program calls 
the database 'PARSE()' call.  The *only* way to reduce that, is to modify your 
client program to make fewer parse calls.

It's possible to reduce the impact of each parse call, by setting 
'session_cached_cursors' to a reasonable number, perhaps 50 or 100, and 
possibly 'cursor_space_for_time=true', but this will NOT change the parse calls 
statistic.

As to why parse calls is 2x the executions, the following is pure speculation, 
since I'm not a VB programmer.

In an ideal world, the program would parse each SQL just once, and then execute 
as many times as needed, possibly binding new values to bind variables before 
each call.  This is what PL/SQL does.  Many applications will parse once per 
execution.  This is not uncommon for clients such as SQL*Plus, for example.  
The really bad programs do things like parse a statement to see if the database 
connection is alive, or to validate that a dynamically generated SQL is 
syntactically correct, and then parse again to execute.  I've even seen/heard 
of code that parses a SQL and then NEVER executes it.  So, anyhow, you end up 
with 2 parses/execution.  However, sometimes, depending on the language, and 
the library used for Oracle communication, it's possible to disable the SQL 
syntactic check or the database connection check, which would drop the number 
of parses from 2x executions to equal to executions.  What the exact root cause 
is in VB, and whether or not it can be disabled, I have no idea.

Hope that helps,

-Mark

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Tracy Rahmlow
Sent: Friday, March 20, 2009 5:09 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Reduce parsing


The following was identified within v$sql in a 10.2.0.4 database -

SQL> select parse_calls, executions, sql_text, module from v$sql
  2  where sql_text like '%INTADM.MASK_DATA(:V%'
  3  and module = 'POLDOC.EXE';

PARSE_CALLS EXECUTIONS
----------- ----------
SQL_TEXT
--------------------------------------------------------------------------------
MODULE
----------------------------------------------------------------
     206855     103410
begin :V00001 := INTADM.MASK_DATA(:V00002,:V00003,:V00004); end;
POLDOC.EXE

The referenced object is a function that is parsed 2x more than it is executed. 
 This is generated from a VB application.  We have other function calls that 
behave similarly (i.e., 2:1 parse to execute).  What  would cause this 
statement to be parsed more than executed?  Are there any options (other than 
removing the call) to reduce the number of parse calls relative to the 
executions?

Thanks

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