[CASSANDRA-10314] Update index file format

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 3.0.0 rc1
• Assignee: Robert Stupp
• Reporter: Robert Stupp

Authors

Robert Stupp

Reviewers

Ariel Weisberg

• Created: 14/Sep/15 10:12
• Updated: 16/Apr/19 09:30
• Resolved: 14/Sep/15 20:09

Description

As CASSANDRA-9738 may not make it into 3.0rc1, but having an off-heap key-cache is still a goal, we should change the index file format to meet off-heap requirements (so I've set fixver to 3.0rc1).

Off-heap (and mmap'd index files) need the offsets of the individual IndexInfo objects and the at least the offset field of IndexInfo structures.

The format I propose is as follows:

 (long) position (vint since 3.0, 64bit before)
  (int) serialized size of data that follows (vint since 3.0, 32bit before)
 -- following for indexed entries only (so serialized size > 0)
 (long) header-length (vint since 3.0)
  (int) DeletionTime.localDeletionTime (32 bit int)
 (long) DeletionTime.markedForDeletionAt (64 bit long)
  (int) number of IndexInfo objects (vint since 3.0, 32bit before)
    (*) serialized IndexInfo objects, see below
    (*) offsets of serialized IndexInfo objects, since version "ma" (3.0)
        Each IndexInfo object's offset is relative to the first IndexInfo object.

    (*) IndexInfo.firstName (ClusteringPrefix serializer, either Clustering.serializer.serialize or Slice.Bound.serializer.serialize)
    (*) IndexInfo.lastName (ClusteringPrefix serializer, either Clustering.serializer.serialize or Slice.Bound.serializer.serialize)
 (long) IndexInfo.offset (vint encoded since 3.0, 64bit int before)
 (long) IndexInfo.width (vint encoded since 3.0, 64bit int before)
 (bool) IndexInfo.endOpenMarker != null              (if 3.0)
  (int) IndexInfo.endOpenMarker.localDeletionTime    (if 3.0 && IndexInfo.endOpenMarker != null)
 (long) IndexInfo.endOpenMarker.markedForDeletionAt  (if 3.0 && IndexInfo.endOpenMarker != null)

Regarding the IndexInfo.offset and .width fields there are two options.

• Serialize both of them or
• Serialize only the offset field plus a last byte offset to be able to recalculate the width of the last IndexInfo

The first option is probably the simpler one, the second saves a few bytes (those of the vint encoded width).

EDIT: update vint fields (as per CASSANDRA-10232)
EDIT2: add header-length fields (as per CASSANDRA-10232)

Issue Links

• is required by: CASSANDRA-9738 Migrate key-cache to be fully off-heap
• links to: Cassci (CI)
• links to: Git branch