Postgres manually alter sequence

Question

I\'m trying to set a sequence to a specific value.

SELECT setval(\'payments_id_seq\'), 21, true

This gives an error:

Answer 1

This syntax isn't valid in any version of PostgreSQL:

ALTER SEQUENCE payments_id_seq LASTVALUE 22

This would work:

ALTER SEQUENCE payments_id_seq RESTART WITH 22;

and is equivalent to:

SELECT setval('payments_id_seq', 22, FALSE);

More in the current manual for ALTER SEQUENCE and sequence functions.

Note that setval() expects either (regclass, bigint) or (regclass, bigint, boolean). In the above example I am providing untyped literals. That works too. But if you feed typed variables to the function you may need explicit type casts to satisfy function type resolution. Like:

SELECT setval(my_text_variable::regclass, my_other_variable::bigint, FALSE);

---

For repeated operations you might be interested in:

ALTER SEQUENCE payments_id_seq START WITH 22; -- set default
ALTER SEQUENCE payments_id_seq RESTART;       -- without value

START [WITH] stores a default RESTART number, which is used for subsequent RESTART calls without value. You need Postgres 8.4 or later for the last part.

Answer 2

setval('sequence_name', sequence_value)

Answer 3

Use select setval('payments_id_seq', 21, true);

setval contains 3 parameters:

• 1st parameter is sequence_name
• 2nd parameter is Next nextval
• 3rd parameter is optional.

The use of true or false in 3rd parameter of setval is as follows:

SELECT setval('payments_id_seq', 21);           // Next nextval will return 22
SELECT setval('payments_id_seq', 21, true);     // Same as above 
SELECT setval('payments_id_seq', 21, false);    // Next nextval will return 21

The better way to avoid hard-coding of sequence name, next sequence value and to handle empty column table correctly, you can use the below way:

SELECT setval(pg_get_serial_sequence('table_name', 'id'), coalesce(max(id), 0)+1 , false) FROM table_name;

where table_name is the name of the table, id is the primary key of the table

Answer 4

The parentheses are misplaced:

SELECT setval('payments_id_seq', 21, true);  # next value will be 22

Otherwise you're calling setval with a single argument, while it requires two or three.

Answer 5

I don't try changing sequence via setval. But using ALTER I was issued how to write sequence name properly. And this only work for me:

1. Check required sequence name using SELECT * FROM information_schema.sequences;

2. ALTER SEQUENCE public."table_name_Id_seq" restart {number};

   In my case it was ALTER SEQUENCE public."Services_Id_seq" restart 8;

Also there is a page on wiki.postgresql.org where describes a way to generate sql script to fix sequences in all database tables at once. Below the text from link:

Save this to a file, say 'reset.sql'

SELECT 'SELECT SETVAL(' ||
       quote_literal(quote_ident(PGT.schemaname) || '.' || quote_ident(S.relname)) ||
       ', COALESCE(MAX(' ||quote_ident(C.attname)|| '), 1) ) FROM ' ||
       quote_ident(PGT.schemaname)|| '.'||quote_ident(T.relname)|| ';'
FROM pg_class AS S,
     pg_depend AS D,
     pg_class AS T,
     pg_attribute AS C,
     pg_tables AS PGT
WHERE S.relkind = 'S'
    AND S.oid = D.objid
    AND D.refobjid = T.oid
    AND D.refobjid = C.attrelid
    AND D.refobjsubid = C.attnum
    AND T.relname = PGT.tablename
ORDER BY S.relname;

Run the file and save its output in a way that doesn't include the usual headers, then run that output. Example:

psql -Atq -f reset.sql -o temp
psql -f temp
rm temp

And the output will be a set of sql commands which look exactly like this:

SELECT SETVAL('public."SocialMentionEvents_Id_seq"', COALESCE(MAX("Id"), 1) ) FROM public."SocialMentionEvents";
SELECT SETVAL('public."Users_Id_seq"', COALESCE(MAX("Id"), 1) ) FROM public."Users";