I have recently lowered gc_grace_seconds
for a CQL table. I am running LeveledCompactionStrategy
. Is it possible for me to force purging of old tombstones from my SSTables?
Your tombstones will disappear on their own through compaction bit make sure you are running repair or they may come back from the dead.
http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_about_deletes_c.html
Tombstones are not immediately available for deletion until both:
1) gc_grace_seconds has expired
2) they meet the requirements configured in tombstone compaction sub-properties
1) Run a repair to ensure your tombstones are consistent
2) Decrease gc_grace_seconds for your table (alter table statement)
3) Configure your compaction sub properties to speed up tombstone removal:
Decrease tombstone_compaction_interval and decrease tombstone_threshold, or set unchecked_tombstone_compaction to true to ignore both conditions and collect based purely on gc grace.
You can see statistics about tombstones in nodetool cfstats
and by using the sstable metatdata utility found in your tools directory sstablemetadata <sstable filenames>
.