This is not possible. Because, each process has and maintain it's own checkpoint file. The extract process once restarted will read this checkpoint file and will come to know where to start writing again and read position.
Multiple Extract cannot write to a single trail file because, it leads to trail file corruption.
But, multiple replicat process can read from single trail file.
Multiple extract --> writing in one trail -- this is not possible
multiple replicat --> reading one same trail -- that is possible
If you have multiple schemas on same database. You can try writing extract which deals with all required tables coming from these schemas.
This way while extracting itself you will extract data from differenct schemas (if that is your requriement)
Then once this data is written into trail -- your replicat can read that.
Just to give you an idea what kind of error comes when you have multiple extracts writing to same trail
ext1 writing at rba 111
ext2 writing at rba 222 or may be it also want to write at 111
and so on
on your trail side GG will not understand what is coming from where.
Hope this helps
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