fix missed check for usedIndexes. (#947)

Author: dcherednik

ydb/core/kqp/opt/physical/effects/kqp_opt_phy_upsert_index.cpp

@@ -365,10 +365,12 @@ TMaybe<TCondenseInputResult> CheckUniqueConstraint(const TExprBase& inputRows, c
     for (const auto& [_, indexDesc] : indexes) {
         hasUniqIndex |= (indexDesc->Type == TIndexDescription::EType::GlobalSyncUnique);
         for (const auto& indexKeyCol : indexDesc->KeyColumns) {
-            if (inputColumns.contains(indexKeyCol)
-                && std::find(mainPk.begin(), mainPk.end(), indexKeyCol) == mainPk.end())
-            {
-                usedIndexes.insert(indexDesc->Name);
+            if (inputColumns.contains(indexKeyCol)) {
+                if (!usedIndexes.contains(indexDesc->Name) &&
+                    std::find(mainPk.begin(), mainPk.end(), indexKeyCol) == mainPk.end())
+                {
+                    usedIndexes.insert(indexDesc->Name);
+                }
             } else {
                 // input always contains key columns
                 YQL_ENSURE(std::find(mainPk.begin(), mainPk.end(), indexKeyCol) == mainPk.end());