Lars George created HBASE-14409:
-----------------------------------
Summary: Clarify use of hbase.hstore.compaction.max.size in
ExploringCompactionPolicy
Key: HBASE-14409
URL: https://issues.apache.org/jira/browse/HBASE-14409
Project: HBase
Issue Type: Bug
Components: Compaction
Affects Versions: 1.1.2, 1.0.2
Reporter: Lars George
Assignee: stack
As discussed in https://issues.apache.org/jira/browse/HBASE-7842:
Why is the {{ExploringCompactionPolicy}} overloading the
{{hbase.hstore.compaction.max.size}} parameter, which is used in the original
ratio-based policy _just_ to exclude store files that are larger than this
threshold. The ECP does the same, but later on uses the same threshold (if set)
to drop a possible selection when the sum of all store files in the selection
exceeds this limit. Why?
Here the code:
{code}
if (size > comConf.getMaxCompactSize()) {
continue;
}
{code}
The ref guide says this:
{noformat}
* Do size-based sanity checks against each StoreFile in this set of StoreFiles.
** If the size of this StoreFile is larger than
`hbase.hstore.compaction.max.size`, take it out of consideration.
** If the size is greater than or equal to `hbase.hstore.compaction.min.size`,
sanity-check it against the file-based ratio to see whether it is too large to
be considered.
{noformat}
This seems wrong, no? It does not do this by each store file, but by the
current selection candidate. It still speaks of the max size key, but here in
the traditional sense, i.e. eliminate single store files that exceed the limit.
But that is not what the code does at this spot.
We should either remove that check, since larger files are already removed in
{{selectCompaction()}} of the base class, or we should see what was meant to
happen here and clarify/fix the code and/or description.
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