Improve performance on concurrent UPDATEs for a timestamp column in Postgres
Would a different kind of column be faster? For example an integer


No. timestamp and timestamptz are just unsigned 64-bit integers internally anyway.


  Is there some way to not lock the column?


It doesn't lock the column. It takes weak table lock that doesn't really block anything except DDL, and takes a row level lock on the row you're updating.

There is no way to prevent the row level lock. It exists because without it behaviour and ordering concurrent updates would be undefined. We don't like undefined behaviour in RDBMSs.

It only blocks concurrent updates of the same row anyway.


  Any other tips to improve this?


Not with the detail provided. There's likely a better way to do what you're trying to do, but it'll probably involve taking a few steps back and looking for a different strategy for solving the underlying problem.

In the specific case of cache invalidation I think you might want to look into LISTEN and NOTIFY. Again though, there just isn't enough info here to go on.