An Oracle initial snapshot is performed by applying a Flashback Query, which uses the AS OF SCN clause to reconstruct the table's data at a specific time. We can use this to our advantage to support multi-threaded captures of a single table.

I propose we alter the behavior for Oracle to extend the createDataEvents methods inside the RelationalSnapshotChangeEventSource as follows:

1. Execute a select to gather the row count for the table based on AS OF SCN
2. Generate a number of "chunks" based on some snapshot.chunk.size property by wrapping the snapshot select with a chunk-based query
3. Submit tasks using the chunk-based query rather than the raw snapshot select so that we can snapshot a single table across multiple threads.