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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Trivial Update of "FAQ" by JonathanEllis
Date Mon, 08 Feb 2010 20:09:53 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for change notification.

The "FAQ" page has been changed by JonathanEllis.
The comment on this change is: link DistributedDeletes.
http://wiki.apache.org/cassandra/FAQ?action=diff&rev1=37&rev2=38

--------------------------------------------------

  
  <<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.
+ 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.
  
  <<Anchor(reads_slower_writes)>>
  == Why are reads slower than writes? ==

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