GitHub user davisp opened a pull request:
https://github.com/apache/couchdb-couch/pull/228
Couchdb 3298 improve couch btree chunkify
This PR adds two slight tweaks to the couch_btree:chunkify/1 function.
First, rather than create a larger number of evenly sized chunks it will
create as few chunks under the configurable chunk threshold as possible with
the final chunk possibly being less full than average.
Second, it prevents the return of a final chunk that has a single key. In
some pathological cases we could end up with a branch of the tree that had
multiple levels of nodes that had a single key. This is caused when a reduce
function is returning values that are larger than the chunk threshold.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/couchdb-couch
COUCHDB-3298-improve-couch-btree-chunkify
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/couchdb-couch/pull/228.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #228
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commit 8556adbb98e79a09ec254967ee6acf3bef8d1fb6
Author: Paul J. Davis <[email protected]>
Date: 2017-02-11T21:26:26Z
Make couch_btree:chunkify/1 prefer fewer chunks
This changes couch_btree:chunkify/1 to produce fewer larger chunks
rather than creating chunks of even-ish size.
COUCHDB-3298
commit ff9fb7112ee5250af01e1b38c8cfa9caed152ae7
Author: Paul J. Davis <[email protected]>
Date: 2017-02-11T21:29:14Z
Ensure multi-item chunks in couch_btree:chunkify/1
If the last element of a chunk has a huge reduction it was possible to
return a btree node that had a single key. This prevents the edge case
by forcing it into the previous chunk. Without this we can end up with a
case where a path in the tree can extend for many levels with only a
single key in each node.
COUCHDB-3298
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