For editing very large documents (file size up to 300 MB) a special memory optimization is implemented on loading such a file so that the total memory allocated for the application is not exceeded. The minimum file size that enables this large file optimization can be configured with the option → → → +Optimize loading in the Text page for files over (MB)
A temporary buffer file is created on disk so you should make sure that the available free disk space is at least double the size of the large file that you want to edit. For example <oXygen/> can load a 200 MB file using a minimum memory setting of 512 MB and at least 400 MB free disk space.
The increase of the maximum size of editable files comes with the following restrictions:
A file with a size larger than the minimum size set with the above option is edited only in Text mode.
The automatic validation is not available in a very large file.
The XPath filter is disabled in the Find/Replace dialog.
The bidirectional Unicode support (right-to-left writing) is disabled.
The option Format and indent the document on open is disabled for non-XML documents. For XML documents it will be done optimizing the memory usage but without respecting the options set in the Oxygen 'Editor/Format' preferences page
Less precise localizations for the results of an XPath expression.
If you get an out of memory error for very large files the total memory that is available to the JVM is not enough. You should apply one or more steps from the following list for avoiding the error:
Set more memory for the application at startup using the -Xmx parameter.
If you have other opened files make sure you close other files before opening the large file.
The large file should be opened in Text editing mode because the needed memory is less than other editing modes. You can set the default editing mode in the Preferences dialog.
If you want only to view the file you can open it in Large File Viewer.