Fix getIndexInfo() sp_statistics fallback for Synapse server (#2839)

Author: Ananya2

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerDatabaseMetaData.java

@@ -296,6 +296,27 @@ private void checkClosed() throws SQLServerException {
     "WHERE t.name = ? AND sch.name = ? AND ic.key_ordinal = 0 " +
     "ORDER BY NON_UNIQUE, TYPE, INDEX_NAME, ORDINAL_POSITION";
 
+    private static final String INDEX_INFO_QUERY_DW = "SELECT db_name() AS TABLE_CAT, " +
+    "sch.name AS TABLE_SCHEM, " +
+    "t.name AS TABLE_NAME, " +
+    "CASE WHEN i.is_unique = 1 THEN 0 ELSE 1 END AS NON_UNIQUE, " +
+    "t.name AS INDEX_QUALIFIER, " +
+    "i.name AS INDEX_NAME, " +
+    "i.type AS TYPE, " +
+    "ic.key_ordinal AS ORDINAL_POSITION, " +
+    "c.name AS COLUMN_NAME, " +
+    "CASE WHEN ic.is_descending_key = 1 THEN 'D' ELSE 'A' END AS ASC_OR_DESC, " +
+    "NULL AS CARDINALITY, " +
+    "NULL AS PAGES, " +
+    "NULL AS FILTER_CONDITION " +
+    "FROM sys.indexes i " +
+    "INNER JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id " +
+    "INNER JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id " +
+    "INNER JOIN sys.tables t ON i.object_id = t.object_id " +
+    "INNER JOIN sys.schemas sch ON t.schema_id = sch.schema_id " +
+    "WHERE t.name = ? " +
+    "AND sch.name = ? " +
+    "ORDER BY NON_UNIQUE, TYPE, INDEX_NAME, ORDINAL_POSITION";
 
     // Use LinkedHashMap to force retrieve elements in order they were inserted
     /** getColumns columns */
@@ -1408,7 +1429,17 @@ private java.sql.ResultSet getIndexInfoAzureDW(String[] arguments, String table,
                         }
                     }
                 }
-                throw e;
+                // If sp_statistics fails (e.g., "PROCEDURE 'sp_statistics' is not supported" in Synapse serverless),
+                // fall back to sys.indexes query
+                if (loggerExternal.isLoggable(Level.FINER)) {
+                    loggerExternal.finer("sp_statistics failed, falling back to sys.indexes: " + e.getMessage());
+                }
+                
+                PreparedStatement fallbackPstmt = (SQLServerPreparedStatement) this.connection.prepareStatement(INDEX_INFO_QUERY_DW);
+                fallbackPstmt.setString(1, table);
+                fallbackPstmt.setString(2, schema);
+                fallbackPstmt.closeOnCompletion();
+                return fallbackPstmt.executeQuery();
             }
             return userRs;
         }