Horton

Consider cheap startup paths in add_paths_to_append_rel

David Rowley <drowley@postgresql.org>

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Commit: a8a968a8212ee3ef7f22795c834b33d871fac262
Author: David Rowley <drowley@postgresql.org>
Date: 2023-10-05T08:03:10Z
Releases: 17.0 
Consider cheap startup paths in add_paths_to_append_rel

6b94e7a6d did this for ordered append paths to allow fast startup
MergeAppends, however, nothing was done for the Append case.

Here we adjust add_paths_to_append_rel() to have it build an AppendPath
containing the cheapest startup paths from each of the child relations
when the append rel has "consider_startup" set.

Author: Andy Fan, David Rowley
Discussion: https://www.postgresql.org/message-id/CAKU4AWrXSkUV=Pt-gRxQT7EbfUeNssprGyNsB=5mJibFZ6S3ww@mail.gmail.com

Files

PathChange+/−
src/backend/optimizer/path/allpaths.c modified +21 −0
src/test/regress/expected/union.out modified +21 −0
src/test/regress/sql/union.sql modified +11 −0

Discussion