Tue Apr 4 13:16:12 PDT 2006
- Previous message: [Slony1-general] primary key for slony
- Next message: [Slony1-general] primary key for slony
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
On 4/4/2006 4:06 PM, Miguel wrote: > Andrew Sullivan wrote: > >>On Tue, Apr 04, 2006 at 11:56:29AM -0600, Miguel wrote: >> >> >>>Ok, the easiest way is create a secuence, but i really need that all the >>>columns have unique values, so i will go with the multiple column key, >>>only 6 columns should not be a problem to slony , should it? :-) >>> >>> >> >>It oughta work. You might find that performance will improve, >>however, if you _also_ add an artificial key. >> >>A >> >> >> > what do you mean by artificial?, the secuence or specify a candidate key > with He means the extra serial column. The difference it makes for slony is that the commands for replicating UPDATE and DELETE operations will read ... WHERE "col1" = 'val1' AND "col2" = 'val2' ... "col6" = 'val6' causing an index lookup with a 6-column scankey instead of a single int4/int8 column one. Sure, that scan will be more expensive. But I think Andrew forgot that using an artificial serial column means that your origin and subscribers must maintain an additional index on all insert/update operations (and vacuum must clean it up after deletes). Andrew, do you have actual experience that it will perform better, or was that an assumption? Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck at Yahoo.com #
- Previous message: [Slony1-general] primary key for slony
- Next message: [Slony1-general] primary key for slony
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
More information about the Slony1-general mailing list