> -----Original Message----- > From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general- > owner@xxxxxxxxxxxxxx] On Behalf Of Andy Colson > Sent: Tuesday, July 15, 2014 4:27 PM > To: pgsql > Subject: [GENERAL] PG index architecture > > I was thinking about indexes, and am kinda curious about sequential access. > > I know nothing of PG guts, so this might even be a dumb question. > > As I understand indexes, they are a key value pair, that contain a value and a > position. You lookup the value then use the position to seek into the > database to load the record. > > Do we, or could we, load all the the matching index records, then sort them > by position? (maybe not all, maybe large batches) > > When loading from the database, if access was slightly more sequential (vs > very random), would it increase performance? > > Said another way: > > I think of table scanning as sequential, and fast. That would be loading db > record 1,2,3, etc. > > Would it be faster to load db records "mostly sequential": 1,3,4,7,10 > compared to randomly: 7,3,10,1,4 > > -Andy > It is called CLUSTER: http://www.postgresql.org/docs/9.2/static/sql-cluster.html Regards, Igor Neyman
