Couchbase 4.5 Community Index Fragmentation 98%

Hi ,

We are using Couchbase Community 4.5 as caching layer. We have seen that the index fragmentation is always @ 98 % .

We have scheduled the compaction for Circular Write Mode that run every night. As soon compaction run it goes down 5 % and again jump back to 98 % in couple of hrs.

018-03-16T05:58:50.482+00:00 [Info] CompactionDaemon: Compacting index instance:16453148617971354242
2018-03-16T05:58:50.486+00:00 [Info] ForestDBSlice::Compact Compacting upto SeqNum 1900. Slice Id 0, IndexInstId 16453148617971354242, IndexDefnId 16453148617971354242
2018-03-16T05:58:50.491+00:00 [Info] ForestDBSlice::Compact(): after compaction, file version ForestDB v2.x format
2018-03-16T05:58:50.491+00:00 [Info] CompactionDaemon: Finished compacting index instance:16453148617971354242

We just have 2 indexes in place :
Definition: CREATE INDEX id_ix ON standard((meta().id))

Definition: CREATE INDEX id_ix ON standard((meta().id))

There is no other issues from functionality and performance side. But like to know why index fragmentation is always high @ 98 %.

Please advice.


@mschettiar, looks like you don’t have much data in the index(SeqNum 1900). With very small data, the percentages can look skewed. Circular reuse generally kicks in around 60% fragmentation and tries to retain that level of fragmentation for the index.


Thank you for the information this helps. In our implementation we are only using Couchbase as a caching layer. Should we be concerned or take any necessary action due to this high index fragmentation 98 %?


No action is required.

Thank You. Much appreciated.