Re: Converting char to varchar automatically

This revised query should give you what you need:

SELECT 'ALTER TABLE ' || quote_ident(n.nspname) || '.'
|| quote_ident(c.relname)
|| ' ALTER COLUMN ' || quote_ident(a.attname) || ' TYPE
varchar(' || i.character_maximum_length || ');'
FROM pg_class c
JOIN pg_namespace n ON n.oid = c.relnamespace
JOIN pg_attribute a ON a.attrelid = c.oid
JOIN pg_type t ON t.oid = a.atttypid
JOIN information_schema.columns i ON (i.table_name = c.relname AND
i.column_name = a.attname)
WHERE t.typname = 'bpchar'
AND c.relkind = 'r'
AND n.nspname <> 'pg_catalog' and not attisdropped;

On Wed, Oct 8, 2014 at 3:34 PM, Andrus <kobruleht2(at)hot(dot)ee> wrote:

> Hi!
>
> Using Toms recommendation I added not attisdropped and now got the query
>
> SELECT 'ALTER TABLE ' || quote_ident(n.nspname) || '.'
> || quote_ident(c.relname)
> || ' ALTER COLUMN ' || quote_ident(a.attname) || ' TYPE
> varchar;'
> FROM pg_class c
> JOIN pg_namespace n ON n.oid = c.relnamespace
> JOIN pg_attribute a ON a.attrelid = c.oid
> JOIN pg_type t ON t.oid = a.atttypid
> WHERE t.typname = 'bpchar'
> AND c.relkind = 'r'
> AND n.nspname <> 'pg_catalog' and not attisdropped;
>
> Will this create commands which replace all user-defined char things in
> database to varchar ?
>
> "TYPE varchar" creates single character column so most alter table command
> will fail.
> How to change this so that original char column width is kept ?
> I looked into tables used in this query but havent found column which holds
> char column defined width.
> How get it or is it better to re-write this query using
> informational_schema
> ?
>
> How to change this query so that it creates single alter table command for
> every table
> (with multiple alter column clauses) to increase conversion speed ?
>
> Andrus.
>

--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.