On Mon, Aug 15, 2005 at 11:07:31AM -0400, Madison Kelly wrote: > This might seem like an odd question but I couldn't find the answer > in the docs (did I miss the obvious?). The serial type is a just convenient way to define an integer column that takes its default value from a sequence, so look for documentation on sequences. Here are some links for the latest release: http://www.postgresql.org/docs/8.0/static/datatype.html#DATATYPE-SERIAL http://www.postgresql.org/docs/8.0/static/sql-createsequence.html http://www.postgresql.org/docs/8.0/static/functions-sequence.html > I want to use a 'serial uniue' column in a table but there is likely > to be many, many inserts and deletes from this column. I was wondering, > what happens when the serial value reaches '2,147,483,647'? Does it roll > back over to '1' and keep going or will the database start erroring out? Sequences are 64 bits, so if you have a 32-bit serial column then you'll probably get an "integer out of range" error when nextval() returns a value higher than 2^31-1 (2,147,483,647). To learn about what happens when all 64 bits are exhausted, see the CYCLE and NO CYCLE options of the CREATE SEQUENCE command. > This isn't likely to be a problem any time soon, but over the course of > a year or more it might be. Consider using bigserial instead of serial -- you'll get 2^63-1 values instead of 2^31-1. If you consume one million values per second, it'll take about 300,000 years for the sequence to cycle. -- Michael Fuhr ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly
