Pyifan opened a new issue #3522:
URL: https://github.com/apache/couchdb/issues/3522
Hi Experts,
We are using couchdb 2.3.1 and we found automatic compaction isn't triggered
as expected. According to documentation, db_fragmentation is computed as:
(file_size - data_size) / file_size * 100
And compaction shall be triggered when the ratio exceeds certain threshold.
However in our usage, we observed that the data_size seems to follow the
increase of file_size rather closely. The fragmentation ratio is never high
enough even when a compact action could potential release a lot of disk space.
Evidence is that after a manually triggered compaction, the db size dropped
from 114G -> 49G (another time it dropped from ~600G -> ~50G). Below is the
file_size and data_size we are getting from GET /{db}:
{"db_name":"testplan","purge_seq":"0-g1AAAAH7eJzLYWBg4MhgTmFQS84vTc5ISXLILEssKDA0MrY0NjHQy0xMKUvMK0lMT9XLLdZLzs_NAapnymMBkgwHgNT____vZyUykGfAA4gB_8k2YAHEgP1kGJCkACST7CmxvQFi-3xybE8A2V5Pnu1JDiDN8eRpTmRIkofozAIAy-Kjpg","update_seq":"610385-g1AAAAITeJzLYWBg4MhgTmFQS84vTc5ISXLILEssKDA0MrY0NjHQy0xMKUvMK0lMT9XLLdZLzs_NAapnSmRIkv___39WEgOjVgKpmpMUgGSSPVS_4QWS9TuA9MdD9etLkaw_AaS_HqpfTYJU_XksQJKhAUgBjZgPMkOHkTwzFkDM2A8yQzmOPDMOQMy4DzJDdQN5ZjyAmAEOD80HWQBw36hU","sizes":{"file":**138221201430**,"external":123142485523,"active":123141079765},"other":{"data_size":**123142485523**},"doc_del_count":365243,"doc_count":169733,"disk_size":138221201430,"disk_format_version":7,"data_size":123141079765,"compact_running":false,"cluster":{"q":8,"n":1,"w":1,"r":1},"instance_start_time":"0"}
{"db_name":"testplan","purge_seq":"0-g1AAAAH7eJzLYWBg4MhgTmFQS84vTc5ISXLILEssKDA0MrY0NjHQy0xMKUvMK0lMT9XLLdZLzs_NAapnymMBkgwPgNR_IMhKZCDVgKQEIJlUT57mRIYkefJ0Qty9AOLu_WQbcABiwH1yPK4A8rg9maHmANIcT4nfGyBOnw80IAsAg6ajpg","update_seq":"610397-g1AAAAITeJzLYWBg4MhgTmFQS84vTc5ISXLILEssKDA0MrY0NjHQy0xMKUvMK0lMT9XLLdZLzs_NAapnSmRIkv___39WEgOjVgKpmpMUgGSSPVS_4SWS9TuA9MdD9evLkqw_AaS_HqpfTYJU_XksQJKhAUgBjZgPMkOHkTwzFkDM2A8yQzmePDMOQMy4DzJDdRN5ZjyAmAEOD80nWQB5F6hg","sizes":{"file":**62651463702**,"external":60378495840,"active":60220917012},"other":{"data_size":**60378495840**},"doc_del_count":365243,"doc_count":169742,"disk_size":62651463702,"disk_format_version":7,"data_size":60220917012,"compact_running":true,"cluster":{"q":8,"n":1,"w":1,"r":1},"instance_start_time":"0"}
I would expect that before the compaction, data_size should be also around
the number of 60378495840 number, so that the computed fragmentation could
reflect the disk space that could potentially be freed by compaction.
Would that be a right expectation? Any suggestions please?
Thanks!!
ps, our compaction related config:
compaction_daemon | check_interval | 3600 |
min_file_size | 131072 |
_default | [{db_fragmentation, "55%"}, {view_fragmentation, "60%"}, {from,
"23:00"}, {to, "05:00"}]
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