sstableexpiredblockers

During compaction, entire sstables can be dropped if they contain only expired tombstones, and if it is guaranteed that the data is not newer than the data in other sstables. An expired sstable can be blocked from getting dropped if its newest timestamp is newer than the oldest data in another sstable.

This tool is used to list all sstables that are blocking other sstables from getting dropped (by having older data than the newest tombstone in an expired sstable) so a user can figure out why certain sstables are still on disk.

ref: https://issues.apache.org/jira/browse/CASSANDRA-10015

Cassandra must be stopped before this tool is executed, or unexpected results will occur. Note: the script does not verify that Cassandra is stopped.

Usage

sstableexpiredblockers [-H] <keyspace> <table>

Options:

-H,--human-readable

Convert timestamps (minTS, maxTS, maxLDT) to ISO 8601 format and display SSTable sizes in human-readable format (e.g., "1.5 MB" instead of raw bytes). Without this flag, raw numeric output is preserved for backward compatibility.

Source: src/java/org/apache/cassandra/tools/SSTableExpiredBlockers.java (CASSANDRA-20448)

Output blocked sstables

If the sstables exist for the table, but no tables have older data than the newest tombstone in an expired sstable, the script will return nothing.

Otherwise, the script will return <sstable> blocks <> expired sstables from getting dropped# followed by a list of the blocked sstables.

Starting in Cassandra 6.0, both human-readable and default output include a diskSize field for each SSTable listed (CASSANDRA-20448).

Default output (raw numeric values, with diskSize):

sstableexpiredblockers keyspace1 standard1

[BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-2-big-Data.db') (minTS = 5, maxTS = 5, maxLDT = 2147483647, diskSize = 36)],  blocks 1 expired sstables from getting dropped: [BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-3-big-Data.db') (minTS = 1536349775157606, maxTS = 1536349780311159, maxLDT = 1536349780, diskSize = 1572864)],

[BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-1-big-Data.db') (minTS = 1, maxTS = 10, maxLDT = 2147483647, diskSize = 36)],  blocks 1 expired sstables from getting dropped: [BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-3-big-Data.db') (minTS = 1536349775157606, maxTS = 1536349780311159, maxLDT = 1536349780, diskSize = 1572864)],

With the -H flag, timestamps are displayed as ISO 8601 instants and disk sizes in human-readable format:

sstableexpiredblockers -H keyspace1 standard1

[BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-2-big-Data.db') (minTS = 1970-01-01T00:00:00.000Z, maxTS = 1970-01-01T00:00:00.000Z, maxLDT = 2038-01-19T03:14:07Z, diskSize = 36 bytes)],  blocks 1 expired sstables from getting dropped: [BigTableReader(path='/var/lib/cassandra/data/keyspace1/standard1-0665ae80b2d711e886c66d2c86545d91/mc-3-big-Data.db') (minTS = 2018-09-07T17:49:35.158Z, maxTS = 2018-09-07T17:49:40.311Z, maxLDT = 2018-09-07T17:49:40Z, diskSize = 1.5 MB)],

Sentinel values (Long.MIN_VALUE, Long.MAX_VALUE) are preserved as raw numbers rather than converted to dates when using -H.