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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2017-01-23 09:38:36 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2017-01-23 09:38:36 -0500 |
| commit | 3c821466abcdb8120ab0dfbce02f3bbae3b62025 (patch) | |
| tree | 848b88abf7fe0982c850e51d0dd514035cf947b2 /src | |
| parent | c0ef456b9714215cae0ce3561c7c83629a7301cf (diff) | |
| download | postgresql-3c821466abcdb8120ab0dfbce02f3bbae3b62025.tar.gz postgresql-3c821466abcdb8120ab0dfbce02f3bbae3b62025.zip | |
Fix example plan in optimizer/README.
Joining three tables only takes two join nodes. I think when I (tgl)
wrote this, I was envisioning possible additional joins; but since the
example doesn't show any fourth table, it's just confusing to write
a third join node.
Etsuro Fujita
Discussion: https://postgr.es/m/e6cfbaa3-af02-1abc-c25e-8fa5c6bc4e21@lab.ntt.co.jp
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/README | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README index 7ae2b74b2c2..fc0fca41071 100644 --- a/src/backend/optimizer/README +++ b/src/backend/optimizer/README @@ -757,9 +757,8 @@ to create a plan like -> Seq Scan on SmallTable1 A NestLoop -> Seq Scan on SmallTable2 B - NestLoop - -> Index Scan using XYIndex on LargeTable C - Index Condition: C.X = A.AID and C.Y = B.BID + -> Index Scan using XYIndex on LargeTable C + Index Condition: C.X = A.AID and C.Y = B.BID so we should be willing to pass down A.AID through a join even though there is no join order constraint forcing the plan to look like this. |