If you give the IS enough memory, it should work. But 200M rows is huge. Also, depending on your pattern, the data may be loaded in memory multiple times in different IS documents (e.g. the JDBC service output document and your target document)
I would recommend to extract it incrementally using the native SQL paging feature of your database
E.g. order by key_field" offset ? rows fetch next ? rows only
Call that in a loop for a reasonable number of rows (E.g. 10M), incrementing the offset until you have all rows
You didn’t specify where you are delivering the data. That is relevant, as you will want to avoid accumulating in memory for the target as well. If you are writing to files, the pub.file services have an append parameter that can be used to incrementally write blocks of data to the file
#webMethods#Integration-Server-and-ESB