Change column type from varchar to text in all tables at once
I guess you don't want to manually run all the necessary ALTER TABLE statements.

You can use the following statement to generate the needed ALTER TABLE statements:

select 'alter table '||table_schema||'.'||table_name||' alter column '||column_name||' type text;'
from information_schema.columns
where table_schema = 'public'
  and column_name = 'description'
  and data_type = 'character varying'
  and character_maximum_length = 255;


replace 'public' with your schema if your tables are not located in the public schema. 

Run the above statement, spool the output into a text file, then run the generated script. 

Something like this:


psql (9.3.4)
Type "help" for help.
postgres=&gt; \t
Showing only tuples.
postgres=&gt; \o alter.sql
postgres=&gt; select 'alter table '||table_schema||'.'||table_name||' alter column '||column_name||' type text;'
postgres-&gt; from information_schema.columns
postgres-&gt; where table_schema = 'public'
postgres-&gt;   and column_name = 'description'
postgres-&gt;   and data_type = 'character varying'
postgres-&gt;   and character_maximum_length = 255;
postgres=&gt; \i alter.sql