Dont consider prefix indices (ydb-platform#12315) (ydb-platform#12345)

Author: ssmike

ydb/core/kqp/opt/logical/kqp_opt_log_ranges_predext.cpp

@@ -333,6 +333,21 @@ TExprBase KqpPushExtractedPredicateToReadTable(TExprBase node, TExprContext& ctx
             for (auto& index : mainTableDesc.Metadata->Indexes) {
                 if (index.Type != TIndexDescription::EType::GlobalAsync && index.State == TIndexDescription::EIndexState::Ready) {
                     auto& tableDesc = kqpCtx.Tables->ExistingTable(kqpCtx.Cluster, mainTableDesc.Metadata->GetIndexMetadata(TString(index.Name)).first->Name);
+
+                    bool uselessIndex = true;
+                    for (size_t i = 0; i < mainTableDesc.Metadata->KeyColumnNames.size(); ++i) {
+                        if (i >= tableDesc.Metadata->KeyColumnNames.size()) {
+                            break;
+                        }
+                        if (mainTableDesc.Metadata->KeyColumnNames[i] != tableDesc.Metadata->KeyColumnNames[i]) {
+                            uselessIndex = false;
+                            break;
+                        }
+                    }
+                    if (uselessIndex) {
+                        continue;
+                    }
+
                     auto buildResult = extractor->BuildComputeNode(tableDesc.Metadata->KeyColumnNames, ctx, typesCtx);
                     bool needsJoin = calcNeedsJoin(tableDesc.Metadata);
 

ydb/core/kqp/ut/opt/kqp_ne_ut.cpp

@@ -4137,8 +4137,10 @@ Y_UNIT_TEST_SUITE(KqpNewEngine) {
                     Key Int32,
                     Fk Int32,
                     Value String,
+                    Value2 String,
                     PRIMARY KEY (Key, Fk),
-                    INDEX Index GLOBAL ON (Value)
+                    INDEX Index GLOBAL ON (Value),
+                    INDEX ByPk GLOBAL ON (Key)
                 );
             )").GetValueSync());
 
@@ -4167,6 +4169,17 @@ Y_UNIT_TEST_SUITE(KqpNewEngine) {
         )", TTxControl::BeginTx(TTxSettings::SerializableRW()), querySettings).GetValueSync();
         AssertSuccessResult(result);
         AssertTableReads(result, "/Root/ComplexKey", 2);
+
+        result = session.ExecuteDataQuery(R"(
+            --!syntax_v1
+            SELECT Key, Fk, Value FROM `/Root/ComplexKey`
+            WHERE Key = 2
+            ORDER BY Value DESC, Value2 DESC
+            LIMIT 1;
+        )", TTxControl::BeginTx(TTxSettings::SerializableRW()), querySettings).GetValueSync();
+        AssertSuccessResult(result);
+        AssertTableReads(result, "/Root/ComplexKey", 2);
+        AssertTableReads(result, "/Root/ComplexKey/ByPk/indexImplTable", 0);
     }
 
     Y_UNIT_TEST(MultipleBroadcastJoin) {