Use list_delete_xxxcell O(1) instead of list_delete_ptr O(N) in some places

From: "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com>
To: PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Use list_delete_xxxcell O(1) instead of list_delete_ptr O(N) in some places
Date: 2020-10-10 02:44:49
Message-ID: b3517353ec7c4f87aa560678fbb1034b@G08CNEXMBPEKD05.g08.fujitsu.local
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Hi

I found some code places call list_delete_ptr can be replaced by list_delete_xxxcell which can be faster.

diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index db54a6b..61ef7c8 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -1005,8 +1005,8 @@ sort_inner_and_outer(PlannerInfo *root,
/* Make a pathkey list with this guy first */
if (l != list_head(all_pathkeys))
outerkeys = lcons(front_pathkey,
- list_delete_ptr(list_copy(all_pathkeys),
- front_pathkey));
+ list_delete_nth_cell(list_copy(all_pathkeys),
+ foreach_current_index(l)));
else
outerkeys = all_pathkeys; /* no work at first one... */

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index fe777c3..d0f15b8 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -650,7 +650,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
if (IsA(rtr, RangeTblRef) &&
rtr->rtindex == rt_index)
{
- newjointree = list_delete_ptr(newjointree, rtr);
+ newjointree = list_delete_cell(newjointree, l);

Best regards,
houzj

Attachment Content-Type Size
0001-Use-list_delete_xxxcell-instead-of-list_delete_ptr.patch application/octet-stream 1.5 KB

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