@@ -14,6 +14,7 @@ import (
1414 "github.com/cockroachdb/cockroach/pkg/sql/sem/volatility"
1515 "github.com/cockroachdb/cockroach/pkg/sql/sessiondatapb"
1616 "github.com/cockroachdb/cockroach/pkg/sql/types"
17+ "github.com/cockroachdb/errors"
1718)
1819
1920// GenericRulesEnabled returns true if rules for optimizing generic query plans
@@ -124,3 +125,64 @@ func (c *CustomFuncs) ParameterizedJoinPrivate() *memo.JoinPrivate {
124125 SkipReorderJoins : true ,
125126 }
126127}
128+
129+ // PlaceholderScanSpanAndPrivate returns a span and scan private for a
130+ // PlaceholderScan expression that is semantically equivalent to the given
131+ // lookup join with input values. See
132+ // ConvertParameterizedLookupJoinToPlaceholderScan for more details.
133+ func (c * CustomFuncs ) PlaceholderScanSpanAndPrivate (
134+ lookupPrivate * memo.LookupJoinPrivate ,
135+ values * memo.ValuesExpr ,
136+ row memo.ScalarListExpr ,
137+ outputCols opt.ColSet ,
138+ ) (span memo.ScalarListExpr , scanPrivate * memo.ScanPrivate , ok bool ) {
139+ // The lookup join must be an inner join.
140+ if lookupPrivate .JoinType != opt .InnerJoinOp {
141+ return nil , nil , false
142+ }
143+ // The lookup join must only have key columns, no lookup expressions.
144+ if len (lookupPrivate .KeyCols ) == 0 ||
145+ lookupPrivate .LookupExpr != nil ||
146+ lookupPrivate .RemoteLookupExpr != nil {
147+ return nil , nil , false
148+ }
149+ // The lookup join must not be part of a paired join.
150+ if lookupPrivate .IsFirstJoinInPairedJoiner || lookupPrivate .IsSecondJoinInPairedJoiner {
151+ return nil , nil , false
152+ }
153+ // The index must be able to produce all the output columns.
154+ md := c .e .f .Metadata ()
155+ indexCols := md .TableMeta (lookupPrivate .Table ).IndexColumns (lookupPrivate .Index )
156+ if ! outputCols .SubsetOf (indexCols ) {
157+ return nil , nil , false
158+ }
159+
160+ // Map columns in the input Values expression to the key columns.
161+ span = make (memo.ScalarListExpr , len (lookupPrivate .KeyCols ))
162+ for i , keyCol := range lookupPrivate .KeyCols {
163+ for j , valCol := range values .Cols {
164+ if keyCol == valCol {
165+ if ! verifyType (md , keyCol , row [j ].DataType ()) {
166+ // TODO(mgartner): This was added to copy the same check
167+ // made while planning the the placeholder fast-path, but it
168+ // may not be necessary here because the lookup join may
169+ // have already checked this.
170+ return nil , nil , false
171+ }
172+ span [i ] = row [j ]
173+ break
174+ }
175+ }
176+ if span [i ] == nil {
177+ panic (errors .AssertionFailedf ("no value found for key column %d" , keyCol ))
178+ }
179+ }
180+
181+ scanPrivate = & memo.ScanPrivate {
182+ Table : lookupPrivate .Table ,
183+ Index : lookupPrivate .Index ,
184+ Cols : outputCols .Copy (),
185+ Locking : lookupPrivate .Locking ,
186+ }
187+ return span , scanPrivate , true
188+ }
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