From 12b90951b90a31427fa2050bd2efcfcd2a3b1969 Mon Sep 17 00:00:00 2001
From: Masha Schneider <masha@cockroachlabs.com>
Date: Wed, 31 Jan 2018 17:21:54 -0500
Subject: [PATCH] sql: add support for scalars on the right of @> in index
 selection

Closes: #21783

Release note: None
---
 .../testdata/logic_test/inverted_index        | 30 ++++++++++++++++
 pkg/sql/opt/index_constraints.go              | 36 ++++++++++++++++++-
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/pkg/sql/logictest/testdata/logic_test/inverted_index b/pkg/sql/logictest/testdata/logic_test/inverted_index
index fcc39efd05da..40abd1b1e6f9 100644
--- a/pkg/sql/logictest/testdata/logic_test/inverted_index
+++ b/pkg/sql/logictest/testdata/logic_test/inverted_index
@@ -286,6 +286,7 @@ SELECT * from d where b @> 'false' ORDER BY a;
 query IT
 SELECT * from d where b @> '1' ORDER BY a;
 ----
+2   [1, 2, 3, 4, "foo"]
 14  1
 
 query IT
@@ -399,6 +400,34 @@ SELECT * from d where b @> '[[]]' ORDER BY a;
 ----
 26  [[], {}]
 
+statement ok
+INSERT INTO d VALUES (27,  '[true, false, null, 1.23, "a"]')
+
+query IT
+SELECT * from d where b @> 'true' ORDER BY a;
+----
+12  true
+27  [true, false, null, 1.23, "a"]
+
+query IT
+SELECT * from d where b @> 'false' ORDER BY a;
+----
+13  false
+27  [true, false, null, 1.23, "a"]
+
+query IT
+SELECT * from d where b @> '1.23' ORDER BY a;
+----
+15  1.23
+27  [true, false, null, 1.23, "a"]
+
+query IT
+SELECT * from d where b @> '"a"' ORDER BY a;
+----
+10  "a"
+19  ["a", "a"]
+27  [true, false, null, 1.23, "a"]
+
 query IT
 SELECT * from d where b IS NULL;
 ----
@@ -428,3 +457,4 @@ query IT
 SELECT * from d where b @> 'null' ORDER BY a;
 ----
 11  null
+27  [true, false, null, 1.23, "a"]
diff --git a/pkg/sql/opt/index_constraints.go b/pkg/sql/opt/index_constraints.go
index 0c6a9efb65c2..50fbbd57bfde 100644
--- a/pkg/sql/opt/index_constraints.go
+++ b/pkg/sql/opt/index_constraints.go
@@ -22,6 +22,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/types"
 	"github.com/cockroachdb/cockroach/pkg/util/encoding"
+	"github.com/cockroachdb/cockroach/pkg/util/json"
 )
 
 // makeEqSpan returns a span that constraints column <offset> to a single value.
@@ -806,10 +807,43 @@ func (c *indexConstraintCtx) makeInvertedIndexSpansForExpr(
 	switch e.op {
 	case containsOp:
 		lhs, rhs := e.children[0], e.children[1]
+
 		if !c.isIndexColumn(lhs, 0 /* index */) || rhs.op != constOp {
 			return nil, false, false
 		}
-		return LogicalSpans{c.makeEqSpan(0 /* offset */, rhs.private.(tree.Datum))}, true, true
+
+		rightDatum := rhs.private.(tree.Datum)
+		rd := rightDatum.(*tree.DJSON).JSON
+
+		switch rd.Type() {
+		case json.ArrayJSONType, json.ObjectJSONType:
+			return LogicalSpans{c.makeEqSpan(0 /* offset */, rhs.private.(tree.Datum))}, true, true
+		default:
+			// If we find a scalar on the right side of the @> operator it means that we need to find
+			// both matching scalars and arrays that contain that value. In order to do this we generate
+			// two logical spans, one for the original scalar and one for arrays containing the scalar.
+			// This is valid because in JSON something can either be an array or scalar so the spans are
+			// guaranteed not to overlap when mapped onto the primary key space. Therefore there won't be
+			// any duplicate primary keys when we retrieve rows for both sets.
+			spans := make(LogicalSpans, 2)
+
+			j := json.NewArrayBuilder(1)
+			j.Add(rd)
+			dJSON, err := tree.MakeDJSON(j.Build())
+			if err != nil {
+				break
+			}
+
+			// This is the span for the scalar.
+			spans[0].Start = LogicalKey{Vals: tree.Datums{rightDatum}, Inclusive: true}
+			spans[0].End = spans[0].Start
+
+			// This is the span to match arrays.
+			spans[1].Start = LogicalKey{Vals: tree.Datums{dJSON}, Inclusive: true}
+			spans[1].End = spans[1].Start
+
+			return spans, true, true
+		}
 
 	case andOp:
 		for _, child := range e.children {