Working with LOB data in the query results

When retrieving large object data you must identify the application that will be used to view the LOB data that has been included in the query results column.

About this task

Retrieving and saving large amounts of data can be time consuming. In order to prevent excessive resource consumption, certain restrictions are placed on a user's ability to retrieve and save large object data. Your ability to retrieve and save LOB data is dictated by the LOB Option resource limit set for your user ID or group by your QMF administrator.

To retrieve or save LOB data:

Procedure

  1. Run a query or procedure that calls the table where the LOB data is stored on the database.
    The LOB data is retrieved from the data source. The contents of each cell in the column that contains LOB data can appear differently depending on the LOB resource limit that has been set for your user ID:
    • If the LOB Retrieval Option resource limit is Retrieve LOB data automatically, then all the LOB data is available to you and displayed in the query results.
      This option pulls all the LOB data for all the LOB columns from the database to the local computer. The actual LOB data is not displayed in grids and reports. Instead, pointers to the LOB data are displayed.
      Note: This option can potentially consume a large amount of resources on the local computer.
    • If the LOB Retrieval Option resource limit is Retrieve LOB data on demand, then each cell in the column containing LOB data is identified with the label, LOB locator. You must initiate the retrieval of the of the LOB data.
  2. To initiate the retrieval of the LOB data, double-click the cell labeled LOB locator. The LOB Type Associations window opens. You can also open the LOB Type Associations window by right-clicking in the header cell of the query results column that contains the LOB data and selecting LOB Type Associations from the pop-up menu.
  3. From the LOB Type Associations window you will identify the type of LOB data that is included in each of the cells of the query results column. The application that will be used to open the LOB data file will be determined based on the file extension that you select. You can select one of the following:
    • Select File Extension to specify the type of LOB data file that will be included in each cell of the query results column. Choose from the drop-down list of available extensions. This option will apply the extension that you select to all cells in the query result column.
    • Select Mapping Column to individually specify which application will be mapped to each LOB data cell in the query results column. From the drop-down list, select the column in the query results that contains the file extension information for the LOB data. Click Mapping. The File Extension Mapping window opens.
      1. The Mapping table includes the following fields:
        • Mapping Value: Lists each unique data type that exists in the mapping column.
        • File Extension: Contains the file extension of the unique data type, and the application that will be used to open the LOB data.
      2. Click the File Extension field. Type the file extension you want to represent the unique data type. For example, if the mapping column in the query results contains the text string "bitmap", you would type a file extension of .bmp. You can also select from a drop-down list of pre-defined file extensions and their associated applications that will be used to open that type of file.
      3. When all file extensions have been specified, click OK. Control returns to the LOB Type Associations window.
  4. Click OK. The Column LOB Type Associations window closes.
  5. To retrieve and view the LOB data you double-click LOB data's cell. The LOB data opens in the designated application. In the query results grid, the label for the cell will change from LOB locator to LOB value to indicate that the LOB data has been retrieved. You can Select Retrieve all LOB values to retrieve all large object data files that are included in the query results column.
    Note: If the data source supports progressive streaming, and the table has LOB TYPE column, the LOB values are automatically fetched. The label for the cell is LOB value.