Hi, On Tue, May 15, 2012 at 12:57 PM, Andres Freund <andres@xxxxxxxxxxx> wrote: > I would rather suggest going with a suming table if you need to do something > like that: > > sequence_id | value > 1 | 3434334 > 1 | 1 > 1 | -1 > 1 | 1 > 1 | 1 > ... > > You then can get the current value with SELECT SUM(value) WHERE sequence_id = > 1. For garbage collection you can delete those values and insert the newly > summed up value again. > That solution won't ever block if done right. I was going to suggest another variant which would not need GC but would also increase concurrency: sequence_id | hash | value 1 | 0 | 3 1 | 1 | 9 1 | 2 | 0 1 | 3 | 2 ... with PK = (sequence_id, hash) and hash in a fixed range (say 0..15). Value would be obtained the same way, i.e. via SELECT SUM(value) FROM T WHERE sequence_id = 1 The hash value would have to be calculated - at session start time (cheap but might reduce concurrency due to small number of changes) or - at TX start time (more expensive but probably better concurrency due to higher change rate) Kind regards robert -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/ -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
