On 25 February 2016 at 09:48, Gabe F. Rudy <r...@goldenhelix.com> wrote:
> Hey all, > > > > I’m building a FDW around a column-store backend (similar to CStore but > for genomic data!). > > > > I have tables in the billions of rows, and have a common query pattern of > asking for the table size (i.e. SELECT COUNT(*) FROM big_fdw_table; ). > > > > This is a read-optimized system in which I know in constant time the exact > dimensions of the table. > > > > Is there any way to convince Postgres FDW to leverage the analyze row > counts or even the “double* totalRowCount” returned from the > AcquireSampleRows callback from my AnalyzeForeignTable function so that it > does not do a full-table scan for a COUNT(*) etc? > > > > My current fallback is to export a specialized function that returns the > table row count for a given FDW table, but that then leaks into the > user-application driving these queries. > Look at TABLESAMPLE, which does mostly what you're asking. -- Simon Riggs http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
