unable to setup postgresql

[vicky]

Binary package hint: postgresql-8.4

After running the "sudo apt-get install postgresql" command, its showing

Setting up postgresql-8.4 (8.4.2-0ubuntu9.10) ...
update-alternatives: using /usr/share/postgresql/8.4/man/man1/postmaster.1.gz to provide /usr/share/man/man1/postmaster.1.gz (postmaster.1.gz) in auto mode.
 * Starting PostgreSQL 8.4 database server * The PostgreSQL server failed to start. Please check the log output.

ProblemType: Package
Architecture: i386
Date: Tue Feb 16 21:55:27 2010
DistroRelease: Ubuntu 9.10
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
Package: postgresql-8.4 8.4.2-0ubuntu9.10
ProcVersionSignature: Ubuntu 2.6.31-19.56-generic
SourcePackage: postgresql-8.4
Title: package postgresql-8.4 8.4.2-0ubuntu9.10 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
Uname: Linux 2.6.31-19-generic i686