Hi Jeff, >> Hi all, >> >> The current discussion about "Indexes on low cardinality columns" let >> me discover this >> "grouped index tuples" patch (http://community.enterprisedb.com/git/) >> and its associated >> "maintain cluster order" patch >> (http://community.enterprisedb.com/git/maintain_cluster_order_v5.patch) >> >> This last patch seems to cover the TODO item named "Automatically >> maintain clustering on a table". > >The TODO item isn't clear about whether the order should be strictly >maintained, or whether it should just make an effort to keep the table >mostly clustered. The patch mentioned above makes an effort, but does >not guarantee cluster order. > You are right, there are 2 different visions : a strictly maintained order or a possibly maintained order. This later is already a good enhancement as it largely decrease the time interval between 2 CLUSTER operations, in particular if the FILLFACTOR is properly set. In term of performance, having 99% of rows in the "right" page is not realy worse than having totaly optimized storage. The only benefit of a strictly maintained order is that there is no need for CLUSTER at all, which could be very interesting for very large databases with 24/24 access constraint. For our need, the "possibly maintained order" is enough. >> As this patch is not so new (2007), I would like to know why it has >> not been yet integrated in a standart version of PG (not well >> finalized ? not totaly sure ? not corresponding to the way the core >> team would like to address this item ?) and if there are good chance >> to see it committed in a near future. > >Search the archives on -hackers for discussion. I don't think either of >these features were rejected, but some of the work and benchmarking have >not been completed. OK, I will have a look. > >If you can help (either benchmark work or C coding), try reviving the >features by testing them and merging them with the current tree. OK, that's the rule of the game in such a community. I am not a good C writer, but I will see what I could do. > I recommend reading the discussion first, to see if there are any major >problems. > >Personally, I'd like to see the GIT feature finished as well. When I >have time, I was planning to take a look into it. > >Regards, > Jeff Davis -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
