如何判断一个集合是否有上限?

问题描述：

我使用的是 PHP mongo 命令:

I was using a PHP mongo command:

$db->command(array("create" => $name, "size" => $size, "capped" => true, "max" => $max));

而且我的收藏已经超出了他们假定的上限.我进行了修复:

And my collections grew way past their supposed capped limits. I put on a fix:

$db->createCollection($name, true, $size, $max);

目前，计数如此之低，我无法判断修复"是否有效.

Currently, the counts are so low I can't tell whether the 'fix' worked.

如何从 shell 或 PHP 判断一个集合是否有上限?我无法在 system.namespaces 中找到此信息.

How can you tell if a collection is capped, either from the shell or PHP? I wasn't able to find this information in the system.namespaces.

答

在 shell 中，使用 db.collection.stats().如果集合有上限:

In the shell, use db.collection.stats(). If a collection is capped:

> db.my_collection.stats()["capped"]
1

如果集合没有上限，则上限"键将不存在.

If a collection is not capped, the "capped" key will not be present.

以下是 stats() 对一个上限集合的示例结果:

Below are example results from stats() for a capped collection:

> db.my_coll.stats()
{
    "ns" : "my_db.my_coll",
    "count" : 221,
    "size" : 318556,
    "avgObjSize" : 1441.4298642533936,
    "storageSize" : 1000192,
    "numExtents" : 1,
    "nindexes" : 0,
    "lastExtentSize" : 1000192,
    "paddingFactor" : 1,
    "flags" : 0,
    "totalIndexSize" : 0,
    "indexSizes" : {

    },
    "capped" : 1,
    "max" : 2147483647,
    "ok" : 1
}

这是 MongoDB 1.7.4.

This is with MongoDB 1.7.4.

如何判断一个集合是否有上限?

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