On 15 August 2018 at 11:11, Edmund Horner <ejr...@gmail.com> wrote: > So we'd extend that to: > - Include in the OR-list "range" subquals of the form (ctid > ? AND > ctid < ?) (either side could be optional, and we have to deal with >= > and <= and having ctid on the rhs, etc.). > - Cost the range subquals by assuming they don't overlap, and > estimating how many blocks and tuples they span. > - When beginning the scan, evaluate all the ?s and build an array of > "tid ranges" to fetch. A tid range is a struct with a starting tid, > and an ending tid, and might just be a single tid item. > - Sort and remove duplicates. > - Iterate over the array, using a single fetch for single-item tid > ranges, and starting/ending a heap scan for multi-item tid ranges. > > I think I'll try implementing this. >
I've set this patch as waiting on author in the commitfest app. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
