for extent extention.
Added a getter, moved some methods from protected into public to use
with unit tests, e.g createFile, setPreallocSpace. Added code stub in
FileOp::oid2FileName to use with UT.
Add more comments.
Changed return value for HDFS'es fallocate.
Removed unnecessary code in ColumnBufferCompressed::writeToFile
Replaced Nulls with Empties in variable names.
HWM for DML and API was being calculated using the first column in a
table instead of the smallest column. This shifts the calculation to the
correct column.
* TEXT and BLOB now have separate identifiers internally
* TEXT columns are identified as such in system catalog
* cpimport only requires hex input for BLOB, not TEXT
* DML writes for multi-block dictionary (blob) now works
* PrimProc fixed so that the first block in multi-block is read
correctly
* Performance optimisation (removed string copy into stack) for new
dictionary entries
