[HBASE-2794] Optimize multi-column scans using Bloom filters
Review Request #2084 - Created Sept. 28, 2011 and updated
Previously we only used row-column Bloom filters for scans that only requested one column. We have seen production queries that request up to 200 columns, and with say ~6 store files per store (region / column family combination) this might have resulted in 1200 block read operations in the worst case. With this diff we will be avoiding seeks on store files that we know don't contain the row/column of interest when using an ExplicitColumnTracker. The performance should remain the same for column range queries.
Existing unit tests. A new unit test (TestScanWithBloomError). Load testing using HBaseTest.