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### A.8.4 Multiple Match Window

The Multiple Match Window allows you to perform matching between more than two tables. It can be obtained by using the Triple Match, Quadruple Match etc () items in the Control Window's Joins menu.

The result is created from the Apparent versions of the tables being joined, so that any row subsets, hidden columns, or sorts currently in force will be reflected in the output. Progress information on the match, which may take some time, is provided in the logging window and by a progress bar at the bottom of the window. When it is completed, you will be informed by a popup window which indicates that a new table has been created. This table will be added to the list in the Control Window and can be examined, manipulated and saved like any other.

The window has the following parts:

Match Criteria box
  Allows you to define what counts as a match between two rows.
Column Selection box
  Allows you to select which table to operate on and which columns supply the matching coordinates.
Match Action box
  Allows selection of which rows are to be included in the output table (for instance whether only those matches which appear in all input tables should result in output rows).
Log window
  Reports on progress as the match is taking place. The progress bar at the bottom of the window also provides an indication of how far through each stage processing has got.
Control buttons
  The Go button starts the search when you are happy with the selections that you have made, and the Stop button interrupts it midway if you decide you no longer want the results (closing the Match Window also interrupts the calculation).

See the comments in Section 5.4 about the semantics of multi-object matches.

For information on the Tuning Parameters (), Full Profiling () and Parallel Execution () toolbar buttons, see Appendix A.8.1.3.

- A.8.4.1 Multiple Match Action Box

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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk