database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-28 18:48:04 +03:00
Code Activity

Allow CustomScan providers to say whether they support projections.

Browse Source 
Previously, all CustomScan providers had to support projections,
but there may be cases where this is inconvenient.  Add a flag
bit to say if it's supported.

Important item for the release notes: this is non-backwards-compatible
since the default is now to assume that CustomScan providers can't
project, instead of assuming that they can.  It's fail-soft, but could
result in visible performance penalties due to adding unnecessary
Result nodes.

Sven Klemm, reviewed by Aleksander Alekseev; some cosmetic fiddling
by me.

Discussion: https://postgr.es/m/CAMCrgp1kyakOz6c8aKhNDJXjhQ1dEjEnp+6KNT3KxPrjNtsrDg@mail.gmail.com
This commit is contained in:
Tom Lane
2021-07-06 18:10:11 -04:00
parent 5798ca5299
commit 955b3e0f92
4 changed files with 26 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/optimizer/plan/createplan.c
View File

@@ -7046,6 +7046,10 @@ is_projection_capable_path(Path *path)
case T_MergeAppend:
case T_RecursiveUnion:
return false;
case T_CustomScan:
if (castNode(CustomPath, path)->flags & CUSTOMPATH_SUPPORT_PROJECTION)
return true;
return false;
case T_Append:
/*
@@ -7092,6 +7096,10 @@ is_projection_capable_plan(Plan *plan)
case T_MergeAppend:
case T_RecursiveUnion:
return false;
case T_CustomScan:
if (((CustomScan *) plan)->flags & CUSTOMPATH_SUPPORT_PROJECTION)
return true;
return false;
case T_ProjectSet:
/*