List all sequences in a Postgres db 8.1 with SQL

Question

I\'m converting a db from postgres to mysql.

Since i cannot find a tool that does the trick itself, i\'m going to convert all postgres sequences to autoincrement id

Answer 1

I know this post is pretty old, but I found the solution by CMS to be very useful as I was looking for an automated way to link a sequence to the table AND column, and wanted to share. The use of pg_depend catalog table was the key. I expanded what was done to:

WITH fq_objects AS (SELECT c.oid,n.nspname || '.' ||c.relname AS fqname ,
                           c.relkind, c.relname AS relation
                    FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace ),

     sequences AS (SELECT oid,fqname FROM fq_objects WHERE relkind = 'S'),
     tables    AS (SELECT oid, fqname FROM fq_objects WHERE relkind = 'r' )
SELECT
       s.fqname AS sequence,
       '->' as depends,
       t.fqname AS table,
       a.attname AS column
FROM
     pg_depend d JOIN sequences s ON s.oid = d.objid
                 JOIN tables t ON t.oid = d.refobjid
                 JOIN pg_attribute a ON a.attrelid = d.refobjid and a.attnum = d.refobjsubid
WHERE
     d.deptype = 'a' ;

This version adds column to the list of fields returned. With both the table name and the column name in hand, a call to pg_set_serial_sequence makes it easy to ensure that all sequences in the database are set correctly. For example:

CREATE OR REPLACE FUNCTION public.reset_sequence(tablename text, columnname text)
 RETURNS void
 LANGUAGE plpgsql
AS $function$
DECLARE
    _sql VARCHAR := '';
BEGIN
    _sql := $$SELECT setval( pg_get_serial_sequence('$$ || tablename || $$', '$$ || columnname || $$'), (SELECT COALESCE(MAX($$ || columnname || $$),1) FROM $$ || tablename || $$), true)$$;
    EXECUTE _sql;
END;
$function$;

Hope this helps someone with resetting sequences!