From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 5 Nov 2013 16:31:35 +0000 (-0500)
Subject: Fix some obsolete information in src/backend/optimizer/README.
X-Git-Tag: REL9_4_BETA1~986
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6331de1d44f01d408aa48c5c996bae8932f7a072;p=postgresql

Fix some obsolete information in src/backend/optimizer/README.

Constant quals aren't handled the same way they used to be.  Also,
add mention of a couple more major steps in grouping_planner.
Per complaint a couple months back from Etsuro Fujita.
---

diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README
index 99203968ba..88cdbc3294 100644
--- a/src/backend/optimizer/README
+++ b/src/backend/optimizer/README
@@ -297,9 +297,6 @@ planner()
   handle UNION/INTERSECT/EXCEPT, GROUP BY, HAVING, aggregates,
 	ORDER BY, DISTINCT, LIMIT
 --query_planner()
-   pull out constant quals, which can be used to gate execution of the
-	whole plan (if any are found, we make a top-level Result node
-	to do the gating)
    make list of base relations used in query
    split up the qual into restrictions (a=1) and joins (b=c)
    find qual clauses that enable merge and hash joins
@@ -318,11 +315,11 @@ planner()
       Back at standard_join_search(), apply set_cheapest() to extract the
       cheapest path for each newly constructed joinrel.
       Loop back if this wasn't the top join level.
-   Back at query_planner:
-    put back any constant quals by adding a Result node
  Back at grouping_planner:
+ convert Path tree returned by query_planner into a Plan tree
  do grouping(GROUP)
  do aggregates
+ do window functions
  make unique(DISTINCT)
  make sort(ORDER BY)
  make limit(LIMIT/OFFSET)