cache ResultSet metadata in getMetaDataMapByMessageId to reduce per-row metadata lookups

Cache ResultSetMetaData (column count, types, and names) before iterating rows so getColumnType/getColumnName are not called for every row. Adjust column indexing and decryption logging to use the cached metadata. This reduces repeated metadata calls and improves performance when reading connector metadata from the database.

Author: NicoPiel

donkey/src/main/java/com/mirth/connect/donkey/server/data/jdbc/JdbcDao.java

@@ -2935,7 +2935,24 @@ private Map<Long, Map<Integer, Map<String, Object>>> getMetaDataMaps(String chan
             statement = connection.prepareStatement(querySource.getQuery("getMetaDataMapByMessageId", values));
             resultSet = statement.executeQuery();
 
+            // Cache ResultSet metadata before the loop — the schema is the same for every row,
+            // so calling getMetaData()/getColumnType()/getColumnName() per row is wasteful.
+            MetaDataColumnType[] columnTypes = null;
+            String[] columnNames = null;
+            int columnCount = 0;
+
             while (resultSet.next()) {
+                if (columnTypes == null) {
+                    ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
+                    columnCount = resultSetMetaData.getColumnCount();
+                    columnTypes = new MetaDataColumnType[columnCount];
+                    columnNames = new String[columnCount];
+                    for (int i = 0; i < columnCount; i++) {
+                        columnTypes[i] = MetaDataColumnType.fromSqlType(resultSetMetaData.getColumnType(i + 1));
+                        columnNames[i] = resultSetMetaData.getColumnName(i + 1).toUpperCase();
+                    }
+                }
+
                 Long messageId = resultSet.getLong("message_id");
                 Integer metaDataId = resultSet.getInt("metadata_id");
 
@@ -2951,29 +2968,26 @@ private Map<Long, Map<Integer, Map<String, Object>>> getMetaDataMaps(String chan
                     connectorMetaDataMap.put(metaDataId, metaDataMap);
                 }
 
-                ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
-                int columnCount = resultSetMetaData.getColumnCount();
-
-                for (int i = 1; i <= columnCount; i++) {
-                    MetaDataColumnType metaDataColumnType = MetaDataColumnType.fromSqlType(resultSetMetaData.getColumnType(i));
+                for (int i = 0; i < columnCount; i++) {
                     Object value = null;
+                    int colIndex = i + 1;
 
-                    switch (metaDataColumnType) {//@formatter:off
+                    switch (columnTypes[i]) {//@formatter:off
                         case STRING:
-                            value = resultSet.getString(i);
+                            value = resultSet.getString(colIndex);
                             if (encryptor != null && StringUtils.startsWith((String) value, Encryptor.HEADER_INDICATOR)) {
                                 try {
                                     value = encryptor.decrypt((String) value);
                                 } catch (Exception e) {
-                                    logger.debug("Unable to decrypt custom metadata column " + resultSetMetaData.getColumnName(i).toUpperCase() + " for channel " + channelId + ", messsage " + messageId + "-" + metaDataId, e);
+                                    logger.debug("Unable to decrypt custom metadata column " + columnNames[i] + " for channel " + channelId + ", messsage " + messageId + "-" + metaDataId, e);
                                 }
                             }
                             break;
-                        case NUMBER: value = resultSet.getBigDecimal(i); break;
-                        case BOOLEAN: value = resultSet.getBoolean(i); break;
+                        case NUMBER: value = resultSet.getBigDecimal(colIndex); break;
+                        case BOOLEAN: value = resultSet.getBoolean(colIndex); break;
                         case TIMESTAMP:
-                            
-                            Timestamp timestamp = resultSet.getTimestamp(i);
+
+                            Timestamp timestamp = resultSet.getTimestamp(colIndex);
                             if (timestamp != null) {
                                 value = Calendar.getInstance();
                                 ((Calendar) value).setTimeInMillis(timestamp.getTime());
@@ -2983,7 +2997,7 @@ private Map<Long, Map<Integer, Map<String, Object>>> getMetaDataMaps(String chan
                         default: throw new Exception("Unrecognized MetaDataColumnType");
                     } //@formatter:on
 
-                    metaDataMap.put(resultSetMetaData.getColumnName(i).toUpperCase(), value);
+                    metaDataMap.put(columnNames[i], value);
                 }
             }