hi, all

It seems WAL.append() in hbase, the javadoc says:

* * Append a set of edits to the WAL. The WAL is not flushed/sync'd after
this transaction*
*   * completes BUT on return this edit must have its region edit/sequence
id assigned*
*   * else it messes up our unification of mvcc and sequenceid.  On return
<code>key</code> will*
*   * have the region edit/sequence id filled in.*

This is really confusing me, if it does does flushed every update is
instantly to disk, how can hbase ensures the WAL contains everything that
was appended? What is hbase's philosophy in this? Does it allow some degree
of data loss?


thanks
hongbin

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