Re: Oracle 10g and DBD::Oracle
- From: psantos@xxxxxxxxxxxxxxx (Peter Santos)
- Date: Fri, 09 Dec 2005 17:08:40 -0500
The bind variable is x.dt which will contain 3 different values for every iteration of the loop.
I'll be more explicit..
Here is what I have in the database:
--select to_char(date_left,'YYYYMMDD')dt from test_t1; 20051129 20051130 20051128
Now for the sql script...
-<<--START-OF-SCRIPT-->>-
var p1 varchar2(100);
var p2 varchar2(100);
exec :p1:='20051128'; :p2:='20051128';
SELECT /*BIND-TEST */ column1,column2,date_left
FROM TEST_T1
WHERE DATE_LEFT BETWEEN TO_DATE(:p1, 'YYYYMMDD') AND TO_DATE(:p2 || ' 235959', 'YYYYMMDD HH24MISS')
/
exec :p1:='20051129'; :p2:='20051129';
SELECT /*BIND-TEST */ column1,column2,date_left
FROM TEST_T1
WHERE DATE_LEFT BETWEEN TO_DATE(:p1, 'YYYYMMDD') AND TO_DATE(:p2 || ' 235959', 'YYYYMMDD HH24MISS')
/
exec :p1:='20051130'; :p2:='20051130';
SELECT /*BIND-TEST */ column1,column2,date_left
FROM TEST_T1
WHERE DATE_LEFT BETWEEN TO_DATE(:p1, 'YYYYMMDD') AND TO_DATE(:p2 || ' 235959', 'YYYYMMDD HH24MISS')
/
--<<-END-OF-SCRIPT-->>-
So before each SELECT I set the bind variables to a new value. This gives me 1 hard parse and 2 soft parses
and ONLY 1 cursor in the database (V$SQL).
HTH
--peter
Reidy, Ron wrote:
This does not look the same. Where are the bind variables?
-----Original Message-----
From: Peter Santos [mailto:psantos@xxxxxxxxxxxxxxx] Sent: Friday, December 09, 2005 7:32 AM
To: Reidy, Ron
Cc: dbi-users@xxxxxxxx
Subject: Re: Oracle 10g and DBD::Oracle
No this issue is not repeatable in SqlPlus.
Here is the test case for sqlplus.
First I updated the table to include 3 records with distinct date_left columns. Just to make it easier to test.
DATE_LEFT =========== 11/28/05 12:13 11/29/05 15:30 11/30/05 19:22
Then I setup my test script which I will show you shortly, but I also executed the following query to give me the total parse and hard parses before and after my query block.
QUERY1: select decode(statistic#,299,'Total parse count (299)', 300,'Hard parse count (300)',statistic#)statistic#, value from v$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:psantos@xxxxxxxxxxxxxxx]
Sent: Thursday, December 08, 2005 9:00 AM
To: dbi-users@xxxxxxxx
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";
}
$dbh->disconnect; exit;
*Here is what's in the Oracle data dictionary*
HASH_VALUE|SQL_ID | ROWSP| EXECS| CHILD#|CHILD_ADDRESS |MODULE
----------|-------------|------|------|--------|----------------|------
----------|-------------|------|------|--------|----------------|-
----------|-------------|------|------|--------|----------------|------
----------|-------------|------|------|--------|----------------|---|
3546516858|2jwh16z9q73bu| 0| 0|0 |0000040144BD2140|perl@[hostname]
3546516858|2jwh16z9q73bu| 2| 1|1 |000004012CECAAF0|perl@[hostname]
** So, 1 query and 2 representations of that same query in the database.
The execute did not shared the cursor prepared by the prepare() call.
SQL > select * from v$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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- From: Ron Reidy
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