In a scan, when a filter's filterKeyValue method returns
ReturnCode.NEXT_ROW - does it actually skip to the next row or just the
next batch, provided of course batching is enabled? Where in the HBase
source code can I find out about this?
I spent some time looking at HRegion.java to get to grips with how
filterRow works (or not) when batching is enabled. In HBase 0.92
hasFilterRow has not been overridden for certain filters which effectively
do filter out rows (SingleColumnValueFilter for example). Thus, these
filters do not generate a warning when used with a batched scan which -
while risky - provides the needed filtering in some cases. This has been
fixed for subsequent versions (at least 0.96) so I need to re-implement
custom filters which use this "effect".