Monthly Archives: November 2008

11g range partition addition script in perl

Recently I wrote a perl script that adds partitions to an existing table
The scripts makes a few assumptions
– The table exists and is range partitioned on date
– There is one partition per day
– There is a local (pre-fixed or non pre-fixed) index on the table
– There is a partition (named tableshortname_default) that is the upperbound of the date range (This can be split into the partitions that we need).
– The partition names are of the format tableshortname_mmddyyyy

The script takes the following arguments
– The table full name
– The table short name (Which becomes the prefix for the partition names)
– The number of partitions to create

The script does the following
– Queries the data dictionary (user_tab_partitions) to find out the highest partition in the table (ie the highest date for which the partition has been created)
– Uses the perl function Add_Delta_Days (Which is the part of the perl library Date::Calc) to generate the future dates for which partitions need to be created.
– Generates partition creation scripts and executes them.
– When you create a table partition, oracle automatically creates the new local index partition too.

The script has been tested against an oracle 11g database.

#!/usr/bin/perl
#There are two arguments to this script
#The first argument is the tablename
#The second argument is the tableshortname used for prefixing the partition names
#The third argument is the number of days for which you want to create new partitions

#This program
#   Assumes that the table is partitioned on date with one partition per day
#   Assumes that the highest partition is the one defined with maxvalues
#   Assumes that the maxvalue partition is called tableshortname_default
#   Takes the tablename
#   Queries the data dictionary to find the partition that has the highest date
#   Creates alter table split partition statements to create the additional partitions (determined by the 3rd argument)
#When the table is split the local index automatically gets split
#But you will have to rename the index partition(So that it gets a good prefix) (The code for that has to be added to this script)

use DBI;
use Date::Calc qw(Add_Delta_Days);

if ( @ARGV < 3 )
{
print “Syntax : crpartitions.pl tablename tableshortname numberofpartitions n”;
exit;
}

# Connect to the database
# LongReadLen and LongTruncOk are required to specify the buffer size
# For the high_value column from user_tab_partitions which is a long datatype

my $db = DBI->connect( “dbi:Oracle:OracleSid”, “username”, “password” )
|| die( $DBI::errstr . “n” );
$db->{AutoCommit}    = 0;
$db->{RaiseError}    = 1;
$db->{ora_check_sql} = 0;
$db->{RowCacheSize}  = 16;
$db->{LongReadLen}   = 5242880;
$db->{LongTruncOk}   = 0;

#Setup tablenames for target table
#Setup a tablename and tableshortname in upper case, to be used in queries

my $l_tablename=shift;
my $l_tableshortname=shift;
my $l_numpartitions=shift;

my $l_tablename_uc=uc($l_tablename);
my $l_tableshortname_uc=uc($l_tableshortname);

# Query user_tab_partitions to determine the highest partition
# And the date that sets the limit for rows that are in that partition

$l_highvalue = $db->selectrow_array(”
select high_value from user_tab_partitions
where table_name = ‘$l_tablename_uc’ and
partition_position = (select max(partition_position)-1 from user_tab_partitions
where table_name = ‘$l_tablename_uc’)
“);

# The output of the query is a string
# eg: TO_DATE(‘ 2008-11-16 00:00:00’, ‘SYYYY-MM-DD HH24:MI:SS’, ‘NLS_CALENDAR=GREGORIA
# Parse the string to get the full date, year, month and day

$l_highdate = substr $l_highvalue,10,19;
$l_year     = substr $l_highdate,0,4;
$l_month    = substr $l_highdate,5,2;
$l_day      = substr $l_highdate,8,2;

# Loop through each new partition you need to create
# Use the Add_Delta_Days function from the Date::Calc perl library
# To add days to the start date to get the upper limit of dates that go into each partition
# Prepare the alter table split partition statement and then invoke the function createPartition
# to execute the statement

for ($i=1 ; $i <= $l_numpartitions; $i++) {
($n_year,$n_month,$n_day)=Add_Delta_Days($l_year,$l_month,$l_day,$i);

$l_alterstmt=”alter table “.$l_tablename_uc.” split partition “.$l_tableshortname_uc.”_default at (TO_DATE(‘”.$n_day.”-“.$n_month.”-“.$n_year.”‘, ‘DD-MM-YYYY’)) into
(PARTITION “.$l_tableshortname_uc.”_”.$n_month.$n_day.$n_year.”,partition “.$l_tableshortname_uc.”_default)”;

&createPartition($db,$l_alterstmt);

}

# Takes the statement passed in as argument and executes it
sub createPartition {

$ldb = shift;
$p_alterstmt=shift;
# execute alter table statement
my $sthd = $ldb->prepare(“$p_alterstmt”)
|| die(“could not prepare alter statement”. $sthd->errstr . “n” );

$sthd->execute()
|| die(“could not execute drop statement”. $sthd->errstr . “n” );

}