The data flow task in SSIS (SQL Server Integration Services) sends data in series of buffers. How much data does one buffer hold? This is bounded by DefaultBufferMaxRows and DefaultBufferMaxSize, two Data Flow properties. They have default values of 10,000 and 10,485,760 (10 MB), respectively. That means, one buffer will contain either 10,000 rows or 10 MB of data, whichever is less.
You can adjust these two properties based on your scenario. Setting them to a higher value can boost performance, but only as long as all buffers fit in memory. In other words, no swapping please!
– Runying Mao