On Tue, Sep 13, 2016 at 9:07 PM, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote: > In the current implementation calls recompute_limits() on the first > invocation of ExecLimit and ExecReScanLimit. Do we expect the > ps->numTuples will be also passed down to the child nodes on the same > timing?
Sure, unless we find some reason why that's not good. > I also think this new executor contract shall be considered as a hint > (but not a requirement) for the child nodes, because it allows the > parent nodes to re-distribute the upper limit regardless of the type > of the child nodes as long as the parent node can work correctly and > has benefit even if the child node returns a part of tuples. It makes > the decision whether the upper limit should be passed down much simple. > The child node "can" ignore the hint but can utilize for more optimization. +1. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
