Filtering Loaded Input Data
Selecting Data by Filtering
Prior to loading data into Message Analyzer through a Data Retrieval Session, you can configure a Session Filter to “select” specific data from your input file configuration to narrow the scope of data retrieval to specific data of interest, reduce the volume of messages that you load, and therefore improve performance. You can also apply a Time Filter to the input file configuration prior to loading data from saved files, such as logs, to reduce the scope of the loaded messages to a specific window of time. These filtering features have a significant impact on processing time and performance improvements.
Selecting Data by Choosing Files
After using the Add Files command on the toolbar of the Files tab in the New Session dialog to create a list of files that contain the data you want to load through your Data Retrieval Session, feasibly from multiple disparate data sources, you can also apply filtering through file selection to create unique message collections. To do this, simply select specific files from among the files that are marked for loading data in the files list to create a subset of messages that you want to focus on. You can then specify a data viewer in which to present the loaded data. After you click the Start button in the New Session dialog, the data loading process is silently invoked in the background.
Selecting Data by Time Filtering
You might have multiple log files containing data that was collected over a period of time from different sources, for example, from a client and server. You might be interested in isolating the source of a TCP connection issue that involved lost TCP segments but it is unclear which machine was dropping packets. You could load data from sets of log files from the same time period, possibly while drilling down to a specific window of time with the use of a Time Filter, to select data that was collected on both client and server computers in a specified time window. When viewing results in an Analysis Session, the data from each set is presented as a single unified message collection with messages interleaved in chronological order. You might also configure a Time Shift if the data sets need to be synchronized, as described in Setting Time Shifts.
Using a Session Filter
You can specify a Session Filter for your Data Retrieval Session by either writing your own Filter Expression or choosing a predefined Filter Expression from the centralized Library. This Library is accessible in the New Session dialog and it contains the same predefined Filter Expressions that you will find in the View Filter Library in the main Message Analyzer analysis surface on the Home tab.
If you want to specify a predefined Filter Expression from the centralized user Library when loading data into Message Analyzer, you should first review the filter functionalities that are described in Filtering Live Trace Session Results and then select an appropriate Session Filter. If you intend to create your own Filter Expression, see the appropriate topic below for more information about how to write one. After you write a Filter Expression or modify a predefined expression that you want to use as a Session Filter, you have the option to save the new Filter Expression to the central Library in the New Session dialog. Even if you do not save it to the Library, you can still apply the filter to the data loading process and observe its performance by simply clicking the Start button in the New Session dialog. When you do, Message Analyzer automatically validates that the expression properly compiles. If the Filter Expression does not compile, you will be unable to load data through this Data Retrieval Session, until you either correct the Filter Expression or delete it entirely. If you have an expression that does not compile, Message Analyzer displays a Compile query Error message.
If your Filter Expression performs as expected and proves to be a useful tool for analysis, you can save it to your centralized Library for future use. Note that such a filter also becomes part of the Message Analyzer sharing infrastructure, which enables you to share filters with other users.
Changing Filter Expressions by Session Editing
You also have the option to edit your Data Retrieval Session after the data loads into Message Analyzer. You can do this by clicking the Edit button in the Session group on the Ribbon of the Message Analyzer Home tab. Thereafter, the Edit Session dialog displays, from where you can choose another Session Filter or configure a different one. Note that you can also add more files to the files list on the Files tab and you can configure a Time Filter as well, as part of your edits. You can apply the changes you make to the session configuration by clicking the Apply button in the Edit Session dialog.