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HBase, mail # user - The write process in the Region Server

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The write process in the Region Server
Amit Sela 2012-06-10, 17:02
Hi all,

I'm trying to better understand what's going on in the region server during
write to HBase.

As I understand the process:

1. Data is written to memstore.
2. Once the memstore has reached hbase.hregion.memstore.flush.size ->
memstore executes flush and writes a new StoreFile.
3. The number of StoreFiles increases until a compaction is triggered.

To my understanding, the compaction is triggered after a compaction check
is done by either CheckCompaction thread running in the background or by
the flush memstore executed.
The compaction triggered will be a minor compaction BUT it could promote to
major if it includes all store files.
When will it NOT include all store files ? say I set compactionThreshld to
3, then when the 3rd (or 4th) flush is executed, a compaction wiil be
triggered and will promote to major since it includes all store files.

Is this right ? can anyone elaborate ?