Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
HBase >> mail # user >> How Log Roller determines the highest sequence number written to a storage file?

Copy link to this message
Re: How Log Roller determines the highest sequence number written to a storage file?
The oldest unflushed sequence numbers are maintained per region in FSHLog.
So, when the region is flushes, only its number is removed (and later
updated to new number).
On Wed, Oct 16, 2013 at 7:42 AM, manjun <[EMAIL PROTECTED]> wrote:

> Hi,
> I was wondering how the last/highest sequence number will be determined if
> suppose. 4 edits arrive sequentially at the Hregion which gets routed to
> corresponding Hregions. Lets say first two (Edit 1 and edit 2) goes to
> region 1. This will write the edits to WAL with sequence number 0 (For edit
> 1) and 1 (for edit 2). And writes the data into memstore. Imagine the
> memstore at region 1 is not full so it won't be flushed. now edits 3 and 4
> arrive at region 2 it writes to WAL with sequence number 2 (for edit 3) and
> 3 (for edit 4) when it writes to memstore imagine the memstore is full so
> it
> gets flushed to disk.
> The questions is:
> Now the last written sequence number is 3 so when logroller runs it
> determines the highest sequence number pushed to disk is 3 so will it
> remove
> all edits in WAL till 3? I am sure this is not the case since edits 0 and 1
> are still in memstore of region 1.
> Can somebody explain or correct my understanding of logroller.
> Thanks
> Manjunath
> --
> View this message in context:
> http://apache-hbase.679495.n3.nabble.com/How-Log-Roller-determines-the-highest-sequence-number-written-to-a-storage-file-tp4051780.html
> Sent from the HBase User mailing list archive at Nabble.com.

NOTICE: This message is intended for the use of the individual or entity to
which it is addressed and may contain information that is confidential,
privileged and exempt from disclosure under applicable law. If the reader
of this message is not the intended recipient, you are hereby notified that
any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.