A Bash script to help re-size a PostgreSQL VARCHAR column to a NEW SIZE, taking care to adjust for required meta-data space. This kind of script greatly helps in scenarios where an existing table (probably with tons of data already) suddenly becomes restricting for certain longer values to be inserted. You might also use it to re-size to a small…

pg_col_resize.sh

#!/usr/bin/sh
if [ -z "$1" ]
then
    echo "Usage: "$0" DBUSER DB TABLE COL NEWSIZE"
else
    USER=$1
    DB=$2
    TABLE=$3
    COL=$4
    SIZE=$5
    echo "Resizing COL ["$COL"] in TABLE ["$DB"."$TABLE"] to "$SIZE
    psql $DB -U $USER <<SQL
    SELECT atttypmod as "CURRENT_SIZE" FROM pg_attribute WHERE attrelid = '$TABLE'::regclass AND attname = '$COL';
    UPDATE pg_attribute SET atttypmod = $SIZE+4 WHERE attrelid = '$TABLE'::regclass AND attname = '$COL';
    SELECT atttypmod as "NEWSIZE" FROM pg_attribute WHERE attrelid = '$TABLE'::regclass AND attname = '$COL';
SQL
fi