This does not look the same. Where are the bind variables?
-----Original Message-----
From: Peter Santos [mailto:[EMAIL PROTECTED]
Sent: Friday, December 09, 2005 7:32 AM
To: Reidy, Ron
Cc: dbi-users@perl.org
Subject: Re: Oracle 10g and DBD::Oracle
No this issue is not repeatable in SqlPlus.
Here is the test case for sqlplus.
First I updated the table to include 3 records with distinct date_left
columns. Just to make it easier to test.
DATE_LEFT
===========
11/28/05 12:13
11/29/05 15:30
11/30/05 19:22
Then I setup my test script which I will show you shortly, but I also
executed the following query to give me the total parse and hard parses
before and after my query block.
QUERY1:
select decode(statistic#,299,'Total parse count (299)', 300,'Hard parse
count (300)',statistic#)statistic#, value from v$mystat where statistic#
in (299,300)
So QUERY1 was executed before and after my little script...
Here is the actual sql block.
DECLARE
col1 varchar2(10);
col2 varchar2(10);
BEGIN
for x in (select to_char(date_left,'YYYYMMDD')dt from PETER_T1)
LOOP
SELECT /*SQL-TEST4 */ column1,column2 INTO col1,col2
FROM PETER_T1
WHERE DATE_LEFT BETWEEN TO_DATE(x.dt, 'YYYYMMDD') AND
TO_DATE(x.dt || ' 235959', 'YYYYMMDD HH24MISS');
END LOOP;
END;
/
The above SQL Block creates only 1 cursor not 2. I also confirmed by
running QUERY1 before and after my block that the first time I have a
hard parse, but subsequent times, it's a soft parse. The parsing
behavior is the same with perl ... meaning the 2nd time the query is
executed it's a soft parse, but there is that 1 extra cursor from the
prepare() in perl, but not via sqlplus.
--peter
Reidy, Ron wrote:
>Peter,
>
>Can you repeat this same issue in SQL*Plus?
>
>--
>Ron Reidy
>Lead DBA
>Array BioPharma, Inc.
>
>-----Original Message-----
>From: Peter Santos [mailto:[EMAIL PROTECTED]
>Sent: Thursday, December 08, 2005 9:00 AM
>To: dbi-users@perl.org
>Subject: re: Oracle 10g and DBD::Oracle
>
>
>Dear users,
>I'm hoping to get some insight into why oracle creates 2 cursors for
>the same sql query when I execute a SELECT statement via my small
>little perl script.
>Here is what is happening .. My query uses 2 bind
>variables and when it is prepared oracle generates 1 cursor for my
>query.
>
>When I execute that prepared statement with actual input bind
>variables,
>
>it generates a 2nd cursor for the same query.
>The problem here is that during the prepare, oracle identifies my 2
>bind
>
>parameters as 2000 character bytes max.
>When I actually execute the query with the binds, it calculates the
>bind
>
>parameters as 32
>characters. So because of bind peeking it thinks it's 2 different
>queries and generates 2 cursors...
>where the first cursor has executions=0.
>
>I can turn off bind peeking with the parameter
>"_optim_peek_user_binds", but then instead of just having a cursor
>mismatch on user_bind_peeking I have a cursor mismatch on
>"bind_mismatch".
>
>Does anyone know how to get around this? This to me is a waste of
>shared pool resources..and we have lots of this happening in our
>database. I've asked oracle for help, but I'm getting nowhere...
>
>Here is the complete test case.
>My env: Solaris 8 - Oracle 10.1.0.4 DBI (version 1.48) and DBD::Oracle
>(version 1.6)
>
>**
>
>*TEST TABLE *
>===========
>CREATE TABLE TEST_T1 (column1 varchar2(10),
>column2 varchar2(10),
>date_left date);
>
>insert into TEST_1 values('Fname','Lname',to_date('20051130
>153015','YYYYMMDD HH24MISS');
>insert into TEST_1 values('Fname','Lname',to_date('20051130
>203015','YYYYMMDD HH24MISS');
>
>*PERL PROGRAM *
>==============
>#!/bin/perl
>use DBI;
>my $dbh = DBI->connect( 'dbi:Oracle:;[mydb]', '[username]',
>'[password]',)
> || die "Database connection not made: $DBI::errstr";
>
>my $date1 = "20051130";
>my $date2 = "20051130";
>
>my $sql = qq{SELECT column1,column2\nfrom TEST_T1\n};
> $sql .= qq{WHERE\ndate_left between to_date( :p1 , 'YYYYMMDD') and
>};
> $sql .= qq{to_date( :p2 || ' 235959', 'YYYYMMDD HH24MISS')};
>
>*# prepare select query *
>my $sth = $dbh->prepare($sql); *# generates cursor1*
>
>$sth->bind_param(":p1",$date1); $sth->bind_param(":p2",$date2);
>$sth->execute(); *# generates cursor2*
>
>print "COLUMN1\tCOLUMN2\n";
>print "=======\t=======\n";
>$sth->bind_columns( \$column1, \$column2);
> while( $sth->fetch() ) {
>print "$column1\t$column2\n";
>
>}
>
>$dbh->disconnect;
>exit;
>
>*Here is what's in the Oracle data dictionary*
>
>HASH_VALUE|SQL_ID | ROWSP| EXECS| CHILD#|CHILD_ADDRESS |MODULE
>----------|-------------|------|------|--------|----------------|------
>----------|-------------|------|------|--------|----------------|-
>----------|-------------|------|------|--------|----------------|------
-
>----------|-------------|------|------|--------|----------------|---
>3546516858|2jwh16z9q73bu| 0| 0|0
>|0000040144BD2140|[EMAIL PROTECTED]
>3546516858|2jwh16z9q73bu| 2| 1|1
>|000004012CECAAF0|[EMAIL PROTECTED]
>
>** So, 1 query and 2 representations of that same query in the
>database.
>
>The execute
> did not shared the cursor prepared by the prepare() call.
>
>SQL > select * from v$sql_shared_cursor where sql_id='2jwh16z9q73bu';
>
>CHILD_ADDRESS
>|CHILD#|U|S|O|O|S|L|S|E|B|P|I|S|T|A|B|D|L|T|R|I|I|R|L|I|O|S|M|*U*|T|
>----------------|------|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-
|
>-|-|-|-|-|
>0000040144BD2140|0
>|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|
>000004012CECAAF0|1
>|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|N|*Y*|N|
>
>SQL>select * from v$sql_bind_metadata where address in
>('0000040144BD2140','000004012CECAAF0');
>
>*** This shows us that cursor1 had different bind variable metadata
>than
>
>cursor2
> which explains why they weren't shared.
>
>ADDRESS | POSITION| DATATYPE|MAX_LENGTH| ARRAY_LEN|BIND_NAME
>----------------|----------|----------|----------|----------|---------
>0000040144BD2140| 1| 1| 2000| 0|P1
>0000040144BD2140| 2| 1| 2000| 0|P2
>000004012CECAAF0| 1| 1| 32| 0|P1
>000004012CECAAF0| 2| 1| 32| 0|P2
>
>
>
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