blocks|key|1232209|text|看起来Mongo+v1.9%2B已经支持这个协议了！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1232210|>+db.runCommand(+{+compact+:+'mycollectionname'+}+)|code-block|syntax|javascript|1232211|请参阅此处的文档：http://docs.mongodb.org/manual/reference/command/compact/|offset|length|1232212|与repairDatabase不同，compact命令不需要双倍的磁盘空间来完成其工作。它在工作时确实需要少量的额外空间。此外，compact命令速度更快。|1232213|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.mongodb.org/manual/reference/command/compact/^0|0|0|9|1L|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

It looks like Mongo v1.9+ has support for the compact in place!

<pre><code>&gt; db.runCommand( { compact : 'mycollectionname' } )
</code></pre>

See the docs here: <a href="http://docs.mongodb.org/manual/reference/command/compact/" rel="noreferrer">http://docs.mongodb.org/manual/reference/command/compact/</a>

"Unlike repairDatabase, the compact command does not require double disk space to do its work. It does require a small amount of additional space while working. Additionally, compact is faster."

blocks|key|1017713|text|我也遇到了同样的问题，只需在命令行执行以下操作即可解决：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017714|mongodump+-d+databasename
echo+'db.dropDatabase()' %7C mongo+databasename
mongorestore+dump/databasename|code-block|syntax|javascript|1017715|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I had the same problem, and solved by simply doing this at the command line:

<pre><code>mongodump -d databasename
echo 'db.dropDatabase()' | mongo databasename
mongorestore dump/databasename
</code></pre>

blocks|key|1232353|text|压缩当前数据库中的所有集合|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1232354|db.getCollectionNames().forEach(function+(collectionName)+{
++++print('Compacting:+'+%2B+collectionName);
++++db.runCommand({+compact:+collectionName+});
});|code-block|syntax|javascript|1232355|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Compact all collections in current database

<pre><code>db.getCollectionNames().forEach(function (collectionName) {
 print('Compacting: ' + collectionName);
 db.runCommand({ compact: collectionName });
});
</code></pre>

blocks|key|1232293|text|如果需要运行完全修复，请使用repairpath选项。将其指向具有更多可用空间的磁盘。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1232294|例如，在我的Mac上，我使用过：|1232295|mongod+--config+/usr/local/etc/mongod.conf+--repair+--repairpath+/Volumes/X/mongo_repair|code-block|syntax|javascript|1232296|更新:根据MongoDB+Core+Server+Ticket+4266，您可能需要添加--nojournal以避免出现错误：|1232297|mongod+--config+/usr/local/etc/mongod.conf+--repair+--repairpath+/Volumes/X/mongo_repair+--nojournal|1232298|entityMap|0|LINK|mutability|MUTABLE|url|https://jira.mongodb.org/browse/SERVER-4266^0|E|A|0|0|0|18|B|5|V|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|O|3|P|5|J|7|19|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

If you need to run a full repair, use the <code>repairpath</code> option. Point it to a disk with more available space.

For example, on my Mac I've used:

<pre><code>mongod --config /usr/local/etc/mongod.conf --repair --repairpath /Volumes/X/mongo_repair
</code></pre>

Update: Per <a href="https://jira.mongodb.org/browse/SERVER-4266" rel="noreferrer">MongoDB Core Server Ticket 4266</a>, you may need to add <code>--nojournal</code> to avoid an error:

<pre><code>mongod --config /usr/local/etc/mongod.conf --repair --repairpath /Volumes/X/mongo_repair --nojournal
</code></pre>

blocks|key|1232510|text|MongoDB3.0及更高版本有一个新的存储引擎--+WiredTiger。在我的例子中，交换引擎将磁盘使用量从100+Gb减少到25+Gb。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1232511|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Mongodb 3.0 and higher has a new storage engine - WiredTiger. 
In my case switching engine reduced disk usage from 100 Gb to 25Gb.

blocks|key|1017638|text|数据库文件的大小不能减小。在“修复”数据库时，mongo服务器只能删除它的一些文件。如果大量数据被删除，mongo服务器将在修复过程中“释放”(删除)一些现有的文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017639|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Database files cannot be reduced in size. While "repairing" database, it is only possible for mongo server to delete some of its files. If large amount of data has been deleted, mongo server will "release" (delete), during repair, some of its existing files.

blocks|key|1232343|text|一般来说，compact比repairDatabase更可取。但是，相对于compact，修复的一个优点是您可以向整个集群发出修复命令。紧凑，你必须登录到每个分片，这是一种恼人。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1232344|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

In general compact is preferable to repairDatabase. But one advantage of repair over compact is you can issue repair to the whole cluster. compact you have to log into each shard, which is kind of annoying.

blocks|key|1017919|text|当我遇到同样的问题时，我停止我的mongo服务器，并使用命令重新启动它|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017920|mongod+--repair|code-block|syntax|javascript|1017921|在运行修复操作之前，您应该检查您的硬盘上是否有足够的可用空间(最小值-是数据库的大小)|1017922|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

When i had the same problem, i stoped my mongo server and started it again with command

<pre><code>mongod --repair
</code></pre>

Before running repair operation you should check do you have enough free space on your HDD (min - is the size of your database)

blocks|key|1017997|text|对于独立模式，您可以使用压缩或修复，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017998|对于分片集群或副本集，根据我的经验，在主数据库上运行compact，然后在次要数据库上运行compact后，主数据库的大小会减小，但次要数据库的大小并没有减小。您可能想要执行resync+member以减小辅助数据库的大小。通过这样做，您可能会发现辅助数据库的大小甚至比主数据库的大小更小，我猜compact命令并没有真正压缩集合。所以，我最终选择了switching+the+primary+and+secondary+of+the+replica+set，并再次使用了resync+member。|offset|length|1017999|我的结论是，减少分片/副本集大小的最好方法是重新同步成员，切换主次，然后再次重新同步。|1018000|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.mongodb.com/manual/tutorial/resync-replica-set-member/|1|https://docs.mongodb.com/manual/tutorial/force-member-to-be-primary/|2^0|0|2F|D|0|4V|1I|1|6K|D|2|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]|$D|X|E|Y|1|Z]|$D|10|E|11|1|12]]|A|$]]|$1|F|3|G|5|6|7|13|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]|P|$5|K|L|M|A|$N|Q]]|R|$5|K|L|M|A|$N|O]]]]

For standalone mode you could use compact or repair,

For sharded cluster or replica set, in my experience, after you running compact on the primary, followed by compact the secondary, the size of primary database reduced, but not the secondary.
You might want to do <a href="https://docs.mongodb.com/manual/tutorial/resync-replica-set-member/" rel="nofollow noreferrer">resync member</a> to reduce the size of secondary database. and by doing this you might find that the size of secondary database is even more reduced than the primary, i guess the compact command not really compacting the collection.
So, i ended up <a href="https://docs.mongodb.com/manual/tutorial/force-member-to-be-primary/" rel="nofollow noreferrer">switching the primary and secondary of the replica set</a> and doing <a href="https://docs.mongodb.com/manual/tutorial/resync-replica-set-member/" rel="nofollow noreferrer">resync member</a> again.

my conclusion is, the best way to reduce the size of sharded/replica set is by doing resync member, switch primary secondary, and resync again.

blocks|key|1017862|text|这只是我能够做到的一种方法。不能保证您现有数据的安全性。试着自担风险。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017863|直接删除数据文件，重启mongod。|1017864|例如，使用ubuntu+(默认数据路径:+/var/lib/mongodb)，我有两个文件，名称类似:+collection.#。我保留了集合.0，并删除了所有其他集合。|1017865|如果数据库中没有严重的数据，这似乎是一种更简单的方法。|1017866|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Just one way that I was able to do it. No guarantee on the safety of your existing data. Try with your own risk.

Delete the data files directly and restart mongod.

For example, with ubuntu (default path to data: /var/lib/mongodb), I had couple files with name like: collection.#. I keep the collection.0 and deleted all others. 

Seems an easier way if you don't have serious data in database.

I've got a MongoDB database that was once large (>3GB). Since then, documents have been deleted and I was expecting the size of the database files to decrease accordingly.

But since MongoDB keeps allocated space, the files are still large.

I read here and there that the admin command <code>mongod --repair</code> is used to free the unused space, but I don't have enough space on the disk to run this command.

Do you know a way I can freed up unused space?

Reducing MongoDB database file size

数据库

服务器

MongoDB

我有一个MongoDB数据库，它曾经很大(>3 3GB)。从那时起，文档已被删除，我预计数据库文件的大小会相应减小。但由于MongoDB保留了已分配的空间，因此文件仍然很大。我到处看到管理命令mongod --repair用于释放未使用的空间，但磁盘上没有足够的空间来运行此命令。你知道有什么方法可以让我腾出不用的空间吗？

问减小MongoDB数据库文件大小
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