Fix SQL query routing to analytics engine for composite-dataformat indices

    The SQL path in RestUnifiedQueryAction.isAnalyticsIndex() was failing to
    route queries to the analytics engine because:

    1. extractIndexName() used context.getParser() which returns SqlV2QueryParser
       (producing UnresolvedPlan), but the SQL branch expected a Calcite SqlNode.
       The V2 parser also treats 'score' as a reserved keyword, causing parse
       failures on common column names.

    2. SqlTableNameExtractor did not handle SqlOrderBy, which Calcite wraps
       around SELECT...LIMIT queries.

    3. Calcite's default parser uppercases unquoted identifiers, but index
       names in OpenSearch are lowercase.

    Fix:
    - Use SqlParser.create(query).parseQuery() (Calcite parser) for the SQL
      branch, which correctly returns SqlNode and handles standard SQL without
      reserved-word conflicts.
    - Add SqlOrderBy handling in SqlTableNameExtractor to unwrap LIMIT queries.
    - Lowercase the extracted table name before cluster state lookup.

Signed-off-by: Finn Carroll <carrofin@amazon.com>

Author: finnegancarroll

plugin/src/main/java/org/opensearch/sql/plugin/rest/RestUnifiedQueryAction.java

@@ -10,14 +10,17 @@
 import static org.opensearch.sql.opensearch.executor.OpenSearchQueryManager.SQL_WORKER_THREAD_POOL_NAME;
 import static org.opensearch.sql.protocol.response.format.JsonResponseFormatter.Style.PRETTY;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.sql.SqlCall;
 import org.apache.calcite.sql.SqlIdentifier;
 import org.apache.calcite.sql.SqlJoin;
 import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlOrderBy;
 import org.apache.calcite.sql.SqlSelect;
+import org.apache.calcite.sql.parser.SqlParser;
 import org.apache.calcite.sql.util.SqlBasicVisitor;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -214,13 +217,14 @@ private void forwardClusterSetting(
    * node. Uses the context's parser which supports both PPL and SQL.
    */
   private static Optional<String> extractIndexName(
-      String query, QueryType queryType, UnifiedQueryContext context) {
+      String query, QueryType queryType, UnifiedQueryContext context) throws Exception {
     if (queryType == QueryType.PPL) {
       UnresolvedPlan unresolvedPlan = (UnresolvedPlan) context.getParser().parse(query);
       return Optional.ofNullable(unresolvedPlan.accept(new IndexNameExtractor(), null));
     }
-    SqlNode sqlNode = (SqlNode) context.getParser().parse(query);
-    return Optional.ofNullable(extractTableNameFromSqlNode(sqlNode));
+    SqlNode sqlNode = SqlParser.create(query).parseQuery();
+    String tableName = extractTableNameFromSqlNode(sqlNode);
+    return Optional.ofNullable(tableName != null ? tableName.toLowerCase(Locale.ROOT) : null);
   }
 
   /** AST visitor that extracts the source index name from a Relation node (PPL path). */
@@ -235,6 +239,9 @@ public String visitRelation(Relation node, Void context) {
   private static class SqlTableNameExtractor extends SqlBasicVisitor<String> {
     @Override
     public String visit(SqlCall call) {
+      if (call instanceof SqlOrderBy orderBy) {
+        return orderBy.query.accept(this);
+      }
       if (call instanceof SqlSelect select) {
         return select.getFrom().accept(this);
       }

plugin/src/test/java/org/opensearch/sql/plugin/rest/RestUnifiedQueryActionTest.java

@@ -65,6 +65,29 @@ public void pluggableDataformatIndexRoutesToAnalytics() {
         action.isAnalyticsIndex("source = opensearch.parquet_logs | fields ts", QueryType.PPL));
   }
 
+  @Test
+  public void sqlQueryRoutesToAnalyticsForCompositeIndex() {
+    registerIndex(
+        "parquet_logs",
+        Settings.builder()
+            .put(IndexSettings.PLUGGABLE_DATAFORMAT_ENABLED_SETTING.getKey(), true)
+            .put(IndexSettings.PLUGGABLE_DATAFORMAT_VALUE_SETTING.getKey(), "composite")
+            .build());
+
+    assertTrue(action.isAnalyticsIndex("SELECT ts, msg FROM parquet_logs", QueryType.SQL));
+    assertTrue(action.isAnalyticsIndex("SELECT ts FROM parquet_logs LIMIT 10", QueryType.SQL));
+    assertTrue(
+        action.isAnalyticsIndex(
+            "SELECT score, name FROM parquet_logs WHERE score > 90", QueryType.SQL));
+  }
+
+  @Test
+  public void sqlQueryRoutesToLuceneForNonCompositeIndex() {
+    registerIndex("plain_logs", Settings.EMPTY);
+
+    assertFalse(action.isAnalyticsIndex("SELECT ts FROM plain_logs", QueryType.SQL));
+  }
+
   @Test
   public void pluggableEnabledButLuceneFormatRoutesToLucene() {
     registerIndex(