Administrating MarkLogic Server

You can manually initiate a merge, either by explicitly issuing the xdmp:merge command as described in Merging the Forests in a Database in the Scripting Administrative Tasks Guide, or by clicking the Merge button on the database configuration page of the Admin Interface. Either of these actions will immediately begin a merge on the database (if using xdmp:merge, on the database to which the App Server that responds to the request is connected, or if using the Admin Interface, the database being configured). Manually initiated merges continue even when merges are disabled for a database.

When you issue an xdmp:merge command or click the Merge button, it will begin a merge even if one would not occur automatically. If no options are specified to xdmp:merge, default values are used (not the configured values for the database).

Manually initiating a merge is useful when you have your merge controls set such that very large merges do not occur (for example, merge min ratio set to 1), but you want to run the large merges during a period of low activity on your system. It can also be useful for expunging deleted fragments that have not yet reached the threshold for automatic merges. Note that if a merge timestamp is set on the database, even a forced merge will not merge out deleted fragments up to the merge timestamp. In normal situations, deleted fragments are retained for a short period of time. If you want to forcibly merge those, you need to explicitly set the merge-timestamp option to the current timestamp in your xdmp:merge call.

The xdmp:merge API also allows you to specify options to the merge to control the maximum merge size, the forests which are merged, whether to merge to a single stand, as well as other options. For details, see xdmp:merge in the MarkLogic documents for Server-Side XQuery APIs.