From 939f5ff996abeb556ed785f3deb64c1b0b970e5c Mon Sep 17 00:00:00 2001
From: Michael Erickson <michae2@cockroachlabs.com>
Date: Thu, 19 Dec 2024 15:41:17 -0800
Subject: [PATCH] wip

---
 pkg/sql/row/updater.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/pkg/sql/row/updater.go b/pkg/sql/row/updater.go
index 55cb1e782c0b..29c2c0770639 100644
--- a/pkg/sql/row/updater.go
+++ b/pkg/sql/row/updater.go
@@ -398,18 +398,18 @@ func (ru *Updater) UpdateRow(
 				oldEntry, newEntry := &oldEntries[oldIdx], &newEntries[newIdx]
 				if oldEntry.Family == newEntry.Family {
 					// If the families are equal, then check if the keys have changed. If so, delete the old key.
-					// Then, issue a CPut for the new value of the key if the value has changed.
+					// Then, issue a CPut for the new key or a Put if only the value has changed.
 					// Because the indexes will always have a k/v for family 0, it suffices to only
 					// add foreign key checks in this case, because we are guaranteed to enter here.
 					oldIdx++
 					newIdx++
-					var expValue []byte
+					var sameKey bool
 					if !bytes.Equal(oldEntry.Key, newEntry.Key) {
 						if err := ru.Helper.deleteIndexEntry(ctx, batch, index, ru.Helper.secIndexValDirs[i], oldEntry, traceKV); err != nil {
 							return nil, err
 						}
 					} else if !newEntry.Value.EqualTagAndData(oldEntry.Value) {
-						expValue = oldEntry.Value.TagAndDataBytes()
+						sameKey = true
 					} else if !index.IsTemporaryIndexForBackfill() {
 						// If this is a temporary index for backfill, we want to make sure we write out all
 						// index values even in the case where they should be the same. We do this because the
@@ -428,13 +428,17 @@ func (ru *Updater) UpdateRow(
 						if traceKV {
 							k := keys.PrettyPrint(ru.Helper.secIndexValDirs[i], newEntry.Key)
 							v := newEntry.Value.PrettyPrint()
-							if expValue != nil {
-								log.VEventf(ctx, 2, "CPut %s -> %v (replacing %v, if exists)", k, v, oldEntry.Value.PrettyPrint())
+							if sameKey {
+								log.VEventf(ctx, 2, "Put %s -> %v", k, v)
 							} else {
 								log.VEventf(ctx, 2, "CPut %s -> %v (expecting does not exist)", k, v)
 							}
 						}
-						batch.CPutAllowingIfNotExists(newEntry.Key, &newEntry.Value, expValue)
+						if sameKey {
+							batch.Put(newEntry.Key, &newEntry.Value)
+						} else {
+							batch.CPutAllowingIfNotExists(newEntry.Key, &newEntry.Value, nil /* expValue */)
+						}
 					}
 					writtenIndexes.Add(i)
 				} else if oldEntry.Family < newEntry.Family {