Replace SSTable*Iterators
-------------------------
Key: CASSANDRA-1095
URL: https://issues.apache.org/jira/browse/CASSANDRA-1095
Project: Cassandra
Issue Type: Sub-task
Reporter: Stu Hood
Fix For: 0.8
Building on the foundation created by CASSANDRA-1092, the goal of this issue is
to replace the db.filter.SSTable*Iterator classes with naive filtering wrapped
around the "sorted list of Slices" abstraction. The goal of this issue is _not_
speed: the filtering done here is very, very naive, but it will be improved in
patch 3 of the 998 series.
This issue begins simplifying and generalizing the QueryFilter API, to allow
more complex queries like "keys in [A:G] and columns in [b, h]". In the current
codebase, this is accomplished by filtering rows independently from the
columns, with keys filtered inside ColumnFamilyStore, and columns filtered by
the SSTable*Iterator classes. This more powerful QueryFilter API also opens the
door for compound filters, which would be prohibitively difficult with the
current API, since each filter currently requires direct file access.
This patch sets up db.filter.FilteredScanner (added in the previous patch) to
use an embedded QueryFilter to perform filtering of a source SeekableScanner.
The QueryFilter class composes implementations of db.filter.IFilter, which
answer two questions:
# might this Slice match the filter? (IFilter.matchesBetween)
# does this Column match the filter? (IFilter.matches)
If it is possible that Columns in a Slice will match the filter, the Slice
cannot be filtered out because its Metadata might need to be resolved against
Metadata from other Scanners. The answer to the second question allows
individual Columns in a Slice to skip deserialization from disk.
For this issue, the SeekableScanner/FilteredScanner API is used to access
SSTables, but the access is wrapped by db.SliceToRowIterator to allow for
Row/ColumnFamily iteration. Memtables will be converted to the Scanner API in
the 3rd issue in the series, which will allow us to remove most of the Slice ->
CF translation layer.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
