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From stack <st...@duboce.net>
Subject Re: Should we change the default value of hbase.regionserver.flushlogentries for 0.21?
Date Sun, 15 Nov 2009 05:45:31 GMT
I'm for leaving it as it is, at every 100 edits -- maybe every 10 edits?
Speed stays as it was.  We used to lose MBs.  By default, we'll now lose 99
or 9 edits max.

We need to do some work bringing folks along regardless of what we decide.
Flush happens at the end of the put up in the regionserver.  If you are
doing a batch of commits -- e.g. using a big write buffer over on your
client -- the puts will only be flushed on the way out after the batch put
completes EVEN if you have configured hbase to sync every edit (I ran into
this this evening.  J-D sorted me out).  We need to make sure folks are up
on this.

St.Ack



On Sat, Nov 14, 2009 at 4:37 PM, Jean-Daniel Cryans <jdcryans@apache.org>wrote:

> Hi dev!
>
> Hadoop 0.21 now has a reliable append and flush feature and this gives
> us the opportunity to review some assumptions. The current situation:
>
> - Every edit going to a catalog table is flushed so there's no data loss.
> - The user tables edits are flushed every
> hbase.regionserver.flushlogentries which by default is 100.
>
> Should we now set this value to 1 in order to have more durable but
> slower inserts by default? Please speak up.
>
> Thx,
>
> J-D
>

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