From 38853eb6d084f4863b04c86759c981ee8de8f659 Mon Sep 17 00:00:00 2001
From: Yahor Yuzefovich <yahor@cockroachlabs.com>
Date: Tue, 10 Sep 2019 13:35:13 -0700
Subject: [PATCH] exec: fix a bug with ON expression support for joiners

Previously, a selection vector was ignored when applying a filter
on the batch. Now this is fixed. It is extremely difficult to write
a unit test for this at the moment because the filter planning code
lives in sql/distsqlrun.

Release note: None
---
 pkg/sql/exec/hashjoiner_test.go  | 1 +
 pkg/sql/exec/joiner_util_tmpl.go | 4 ++++
 pkg/sql/exec/mergejoiner_test.go | 2 ++
 3 files changed, 7 insertions(+)

diff --git a/pkg/sql/exec/hashjoiner_test.go b/pkg/sql/exec/hashjoiner_test.go
index 5325ab911d00..aa27ef52b43e 100644
--- a/pkg/sql/exec/hashjoiner_test.go
+++ b/pkg/sql/exec/hashjoiner_test.go
@@ -38,6 +38,7 @@ func TestHashJoinerInt64(t *testing.T) {
 		}
 	}
 
+	// TODO(yuzefovich): add unit tests for cases with ON expression.
 	tcs := []struct {
 		leftTypes  []coltypes.T
 		rightTypes []coltypes.T
diff --git a/pkg/sql/exec/joiner_util_tmpl.go b/pkg/sql/exec/joiner_util_tmpl.go
index 05cb7d9d326b..42b372594e3b 100644
--- a/pkg/sql/exec/joiner_util_tmpl.go
+++ b/pkg/sql/exec/joiner_util_tmpl.go
@@ -136,6 +136,10 @@ func (f *joinerFilter) setInputBatch(lBatch, rBatch coldata.Batch, lIdx, rIdx in
 		execerror.VectorizedInternalPanic("only one of lBatch and rBatch can be nil")
 	}
 	setOneSide := func(colOffset int, batch coldata.Batch, sourceTypes []coltypes.T, idx int) {
+		sel := batch.Selection()
+		if sel != nil {
+			idx = int(sel[idx])
+		}
 		for colIdx := 0; colIdx < batch.Width(); colIdx++ {
 			colType := sourceTypes[colIdx]
 			col := batch.ColVec(colIdx)
diff --git a/pkg/sql/exec/mergejoiner_test.go b/pkg/sql/exec/mergejoiner_test.go
index d0e955431c88..6f764230cfea 100644
--- a/pkg/sql/exec/mergejoiner_test.go
+++ b/pkg/sql/exec/mergejoiner_test.go
@@ -26,6 +26,8 @@ type mjTestInitializer interface {
 	initWithBatchSize(outBatchSize uint16)
 }
 
+// TODO(yuzefovich): add unit tests for cases with ON expression.
+
 type mjTestCase struct {
 	description     string
 	joinType        sqlbase.JoinType