[#24930] YSQL: Remove superfluous field use_secondary_index from PgPr…

…epareParameters

Summary:
The `PgPrepareParameters` has the `index_relfilenode_oid` field which can be used to detect when it is required to use secondary index. The `use_secondary_index` field is superfluous because it allows undesired data state: `use_secondary_index` is `true` and `index_relfilenode_oid` is `kInvalidOid`.
Jira: DB-14072

Test Plan: Jenkins

Reviewers: amartsinchyk, telgersma

Reviewed By: amartsinchyk

Subscribers: yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D40002

src/postgres/src/backend/access/yb_access/yb_scan.c

@@ -733,7 +733,7 @@ ybcSetupScanPlan(bool xs_want_itup, YbScanDesc ybScan, YbScanPlan scan_plan)
 	 * types of scan.
 	 * - "querying_colocated_table": Support optimizations for (system,
 	 *   user database and tablegroup) colocated tables
-	 * - "index_oid, index_only_scan, use_secondary_index": Different index
+	 * - "index_oid, index_only_scan": Different index
 	 *   scans.
 	 * NOTE: Primary index is a special case as there isn't a primary index
 	 * table in YugaByte.
@@ -763,16 +763,15 @@ ybcSetupScanPlan(bool xs_want_itup, YbScanDesc ybScan, YbScanPlan scan_plan)
 
 	if (index)
 	{
-		ybScan->prepare_params.index_relfilenode_oid =
-			ybScan->prepare_params.fetch_ybctids_only &&
-				YBIsCoveredByMainTable(index)
-					? YbGetRelfileNodeId(relation)
-					: YbGetRelfileNodeId(index);
-		ybScan->prepare_params.index_only_scan = xs_want_itup;
-		ybScan->prepare_params.use_secondary_index =
-			!YBIsCoveredByMainTable(index) ||
-			(ybScan->prepare_params.fetch_ybctids_only &&
-			 !ybScan->prepare_params.querying_colocated_table);
+		YBCPgPrepareParameters *params = &ybScan->prepare_params;
+		params->index_relfilenode_oid = InvalidOid;
+		params->index_only_scan = xs_want_itup;
+		if (!YBIsCoveredByMainTable(index))
+			params->index_relfilenode_oid = YbGetRelfileNodeId(index);
+		else if (params->index_only_scan ||
+				(params->fetch_ybctids_only &&
+				 !params->querying_colocated_table))
+			params->index_relfilenode_oid = YbGetRelfileNodeId(relation);
 	}
 
 	/* Setup descriptors for target and bind. */

src/postgres/src/backend/access/ybgin/ybginscan.c

@@ -104,7 +104,6 @@ ybginrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
 	YBCPgPrepareParameters prepare_params = {
 		.index_relfilenode_oid = YbGetRelfileNodeId(scan->indexRelation),
 		.index_only_scan = scan->xs_want_itup,
-		.use_secondary_index = true, /* can't have ybgin primary index */
 		.querying_colocated_table = querying_colocated_table,
 	};
 	HandleYBStatus(YBCPgNewSelect(YBCGetDatabaseOid(scan->heapRelation),

src/yb/yql/pggate/pggate.cc

@@ -167,14 +167,7 @@ std::optional<PgSelect::IndexQueryInfo> MakeIndexQueryInfo(
 Result<std::unique_ptr<PgStatement>> MakeSelectStatement(
     const PgSession::ScopedRefPtr& pg_session, const PgObjectId& table_id,
     const PgObjectId& index_id, const PgPrepareParameters* prepare_params, bool is_region_local) {
-  // Scenarios:
-  // - Sequential Scan: PgSelect to read from table_id.
-  // - Primary Scan: PgSelect from table_id. YugaByte does not have separate table for primary key.
-  // - Index-Only-Scan: PgSelectIndex directly from secondary index_id.
-  // - IndexScan: Use PgSelectIndex to read from index_id and then PgSelect to read from table_id.
-  //     Note that for SysTable, only one request is send for both table_id and index_id.
-  if (prepare_params && prepare_params->index_only_scan && prepare_params->use_secondary_index) {
-    RSTATUS_DCHECK(index_id.IsValid(), InvalidArgument, "Cannot run query with invalid index ID");
+  if (prepare_params && prepare_params->index_only_scan) {
     return PgSelectIndex::Make(pg_session, index_id, is_region_local);
   }
 
@@ -1463,6 +1456,9 @@ Status PgApiImpl::ExecTruncateColocated(PgStatement* handle) {
 Status PgApiImpl::NewSelect(
     const PgObjectId& table_id, const PgObjectId& index_id,
     const PgPrepareParameters* prepare_params, bool is_region_local, PgStatement** handle) {
+  DCHECK(index_id.IsValid() || table_id.IsValid());
+  DCHECK(!(prepare_params && prepare_params->index_only_scan) || index_id.IsValid());
+
   *handle = nullptr;
   return AddToCurrentPgMemctx(
       VERIFY_RESULT(MakeSelectStatement(

src/yb/yql/pggate/ybc_pg_typedefs.h

@@ -230,19 +230,18 @@ typedef struct PgSysColumns {
 //
 // Index-related parameters are used to describe different types of scan.
 //   - Sequential scan: Index parameter is not used.
-//     { index_relfilenode_oid, index_only_scan, use_secondary_index }
-//        = { kInvalidRelfileNodeOid, false, false }
+//     { index_relfilenode_oid, index_only_scan}
+//        = { kInvalidRelfileNodeOid, false}
 //   - IndexScan:
-//     { index_relfilenode_oid, index_only_scan, use_secondary_index }
-//        = { IndexRelfileNodeOid, false, true }
+//     { index_relfilenode_oid, index_only_scan}
+//        = { IndexRelfileNodeOid, false}
 //   - IndexOnlyScan:
-//     { index_relfilenode_oid, index_only_scan, use_secondary_index }
-//        = { IndexRelfileNodeOid, true, true }
+//     { index_relfilenode_oid, index_only_scan}
+//        = { IndexRelfileNodeOid, true}
 //   - PrimaryIndexScan: This is a special case as YugaByte doesn't have a separated
 //     primary-index database object from table object.
 //       index_relfilenode_oid = TableRelfileNodeOid
 //       index_only_scan = true if ROWID is wanted. Otherwise, regular rowset is wanted.
-//       use_secondary_index = false
 //
 // Attribute "querying_colocated_table"
 //   - If 'true', SELECT from colocated tables (of any type - database, tablegroup, system).
@@ -251,7 +250,6 @@ typedef struct PgSysColumns {
 typedef struct PgPrepareParameters {
   YBCPgOid index_relfilenode_oid;
   bool index_only_scan;
-  bool use_secondary_index;
   bool querying_colocated_table;
   bool fetch_ybctids_only;
 } YBCPgPrepareParameters;

src/yb/yql/pggate/ybc_pggate.cc

@@ -1533,18 +1533,13 @@ YBCStatus YBCPgExecTruncateColocated(YBCPgStatement handle) {
 }
 
 // SELECT Operations -------------------------------------------------------------------------------
-YBCStatus YBCPgNewSelect(const YBCPgOid database_oid,
-                         const YBCPgOid table_relfilenode_oid,
-                         const YBCPgPrepareParameters *prepare_params,
-                         bool is_region_local,
-                         YBCPgStatement *handle) {
-  const auto index_oid = prepare_params && prepare_params->use_secondary_index
-      ? prepare_params->index_relfilenode_oid
-      : kInvalidOid;
-  const auto index_id =
-      index_oid == kInvalidOid ? PgObjectId{} : PgObjectId{database_oid, index_oid};
+YBCStatus YBCPgNewSelect(
+    YBCPgOid database_oid, YBCPgOid table_relfilenode_oid, const YBCPgPrepareParameters* params,
+    bool is_region_local, YBCPgStatement* handle) {
   return ToYBCStatus(pgapi->NewSelect(
-      {database_oid, table_relfilenode_oid}, index_id, prepare_params, is_region_local, handle));
+      PgObjectId{database_oid, table_relfilenode_oid},
+      PgObjectId{database_oid, params ? params->index_relfilenode_oid : kInvalidOid},
+      params, is_region_local, handle));
 }
 
 YBCStatus YBCPgSetForwardScan(YBCPgStatement handle, bool is_forward_scan) {