The Integration Service uses a data cache to store XML row data while it generates an XML document. The cache size is the sum of all the groups in the XML target instance. The cache includes a primary key and a foreign key index cache for each XML group and one data cache for all groups.
You can configure the Integration Service to automatically determine the XML cache size, or you can configure the cache size. When the memory requirements exceed the cache size, the Integration Service pages data to index and data files in the cache directory. When the session completes, the Integration Service releases cache memory and deletes the cache files.
You can specify the cache directory and cache size for the XML target. The default cache directory is $PMCacheDir, which is a service process variable that represents the directory where the Integration Service stores cache files by default.