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The "FAQ_JP" page has been changed by shot6. http://wiki.apache.org/cassandra/FAQ_JP?action=diff&rev1=53&rev2=54 -------------------------------------------------- }}} <<Anchor(i_deleted_what_gives)>> - == I delete data from Cassandra, but disk usage stays the same. What gives? == - Data you write to Cassandra gets persisted to SSTables. Since SSTables are immutable, the data can't actually be removed when you perform a delete, instead, a marker (also called a "tombstone") is written to indicate the value's new status. Never fear though, on the first compaction that occurs after ''GCGraceSeconds'' (hint: storage-conf.xml) have expired, the data will be expunged completely and the corresponding disk space recovered. See DistributedDeletes for more detail. + == Cassandraからデータを削除したのにディスク使用量は同じです.何が起こってるのでしょうか? == + + Cassandraに書き込まれたデータは[[MemtableSSTable_JP|SSTables]]に書き込まれます．SSTablesはイミュータブルで、データ削除を実行してもマーカー(tombstoneといいます)が書き込まれるだけで実際には削除されません．でも大丈夫．GCGraceSeconds後の最初のコンパクションでデータは完璧に抹消され、ディスクスペースはそのときに軽減されます．詳しくは[[DistributedDeletes_JP|DistributedDeletes]]を参照してください． + <<Anchor(reads_slower_writes)>> == Why are reads slower than writes? ==
