Vladimir Rodionov created HBASE-13884:
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Summary: Fix Compactions section in HBase book
Key: HBASE-13884
URL: https://issues.apache.org/jira/browse/HBASE-13884
Project: HBase
Issue Type: Bug
Components: documentation
Reporter: Vladimir Rodionov
Priority: Trivial
http://hbase.apache.org/book.html#_compaction
{quote}
Being Stuck
When the MemStore gets too large, it needs to flush its contents to a
StoreFile. However, a Store can only have hbase.hstore.blockingStoreFiles
files, so the MemStore needs to wait for the number of StoreFiles to be reduced
by one or more compactions. However, if the MemStore grows larger than
hbase.hregion.memstore.flush.size, it is not able to flush its contents to a
StoreFile. If the MemStore is too large and the number of StoreFiles is also
too high, the algorithm is said to be "stuck". The compaction algorithm checks
for this "stuck" situation and provides mechanisms to alleviate it.
{quote}
According to source code, this "stuck" situation has nothingg to do with
MemStore size.
{code}
// Stuck and not compacting enough (estimate). It is not guaranteed that we
will be
// able to compact more if stuck and compacting, because ratio policy
excludes some
// non-compacting files from consideration during compaction (see
getCurrentEligibleFiles).
int futureFiles = filesCompacting.isEmpty() ? 0 : 1;
boolean mayBeStuck = (candidateFiles.size() - filesCompacting.size() +
futureFiles)
>= storeConfigInfo.getBlockingFileCount();
{code}
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