OLE DB Destination - Fast Load With Maximum Insert Commit Size

I'm seeing some strange behavior from the OLE DB Destination when using the "fast load" access mode and setting the "Maximum insert commit size".

When I do not set the "Rows per batch" or the "Maximum insert commit size", the package I'm working with inserts 123,070 rows using a single "insert bulk" statement. The data seems to flow through the pipeline until it gets to the OLE DB Destination and then I see a short pause. I'm assuming the pause is from the "insert bulk" statement handling all of the rows at once.

When I set the "Rows per batch" option but leave the "Maximum insert commit size" alone, I generally see the same behavior -- a single "insert bulk" statement that handles all 123,070. In this case, however, the "insert bulk" statement has a "ROWS_PER_BATCH" option appended to the statement that matches the "Rows per batch" setting. This makes sense. I'm assuming the "insert bulk" then "batches" the rows into multiple insert statements (although I'm unsure of how to confirm this). This version of the "insert bulk" statement appears to run in about the same time as the case above.

When I set the "Maximum insert commit size" option and leave the "Rows per batch" statement alone, I see multiple "insert bulk" statements being executed, each handling the lower of either the value I specify for the "Maximum insert commit size" or the number of rows in a single buffer flowing through the pipeline. In my testing, the number of rows in a buffer was 9,681. So, if I set the "Maximum insert commit size" to 5,000, I see two "insert bulk" statements for each buffer that flows into the OLE DB Destination (one handling 5,000 rows and one handling 4,681 rows). If I set the "Maximum insert commit size" to 10,000, I see a single "insert bulk" statement for each buffer that flows into the OLE DB Destination (handling 9,681 rows).

Now the problem. When I set the "Maximum insert commit size" as described in the last case above, I see LONG pauses between buffers being handled by the OLE DB Destination. For example, I might see one buffer of data flow through (and be handled by one or more "insert bulk" statements based on the "Maximum insert commit size" setting), then see a 2-3 minute pause before the next buffer of data is handled (with its one or more "insert bulk" statements being executed). Then I might see a 4-5 minute pause before the next buffer of data is handled. The pause between the buffers being passed through the OLE DB Destination (and handled via the "insert bulk" statements) is sometimes shorter, sometimes longer.

Using Profiler, I don't see any other activity going on within the database or within SQL Server itself that would explain the pauses between the buffers being handled by the OLE DB Destination and the resulting "insert bulk" statements...

Can anyone explain what is going on here? Is setting the "Maximum insert commit size" a bad idea? What are the differences between it and the "Rows per batch" setting and what are the recommended uses of these two options to try to improve the performance of the insert (particularly when handling millions of rows)?

TIA for any thoughts or information...

Dave Fackler