Hello 2010/5/12 Louis-David Mitterrand <vindex+lists-pgsql-...@apartia.org>: > Hi, > > I have a large dataset (page 1 at http://www.cruisefish.net/stat.md) and > am in the process of developping a pager to let users leaf through it > (30K rows). > > Ideally I'd like to know when requesting any 'page' of data where I am > within the dataset: how many pages are available each way, etc. > > Of course that can be done by doing a count(*) query before requesting a > limit/offset subset. But the main query is already quite slow, so I'd > like to minimize them.
look on scrollable cursors. see DECLARE CURSOR statement Regards Pavel Stehule > > But I am intrigued by window functions, especially the row_number() and > ntile(int) ones. > > Adding "row_number() over (order by <reverse query>)" to my query will > return the total number of rows in the first row, letting my deduce the > number of pages remaining, etc. row_number() apparently adds very little > cost to the main query. > > And ntile(buckets) seems nice too but I need the total row count for it > to contain a 'page' number: ntile(row_count/page_size). > > What better "paging" strategies are out there? > > Thanks, > > -- > Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-sql > -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
