mongodb 优化

固定集合     如果空间用完 新的值将取代集合中旧的值

创建一个固定集合

db.createCollection('c2',{capped:true,size:1000000,max:5});  大小1M   存5个json数据 { "ok" : 1 }> db.c2.stats();{        "ns" : "test.c2",        "count" : 0,        "size" : 0,        "storageSize" : 1000192,        "numExtents" : 1,        "nindexes" : 0,        "lastExtentSize" : 1000192,        "paddingFactor" : 1,        "flags" : 0,        "totalIndexSize" : 0,        "indexSizes" : {        },        "capped" : 1,   //固定集合        "max" : 5,     // 只能存5个        "ok" : 1}把普通集合  转换成固定集合db.runCommand({converTocapped:'c1',size:100000,size:5});    > show tables;c1c2system.indexes> db.c2.find();> db.c2.insert({'name':'user1'});> db.c2.insert({'name':'user2'});> db.c2.insert({'name':'user3'});> db.c2.insert({'name':'user4'});> db.c2.insert({'name':'user5'});> db.c2.find();{ "_id" : ObjectId("55c21166d9c7fa428406b564"), "name" : "user1" }{ "_id" : ObjectId("55c2116cd9c7fa428406b565"), "name" : "user2" }{ "_id" : ObjectId("55c2116fd9c7fa428406b566"), "name" : "user3" }{ "_id" : ObjectId("55c21175d9c7fa428406b567"), "name" : "user4" }{ "_id" : ObjectId("55c21179d9c7fa428406b568"), "name" : "user5" }> db.c2.insert({'name':'user6'});> db.c2.find();                  { "_id" : ObjectId("55c2116cd9c7fa428406b565"), "name" : "user2" }{ "_id" : ObjectId("55c2116fd9c7fa428406b566"), "name" : "user3" }{ "_id" : ObjectId("55c21175d9c7fa428406b567"), "name" : "user4" }{ "_id" : ObjectId("55c21179d9c7fa428406b568"), "name" : "user5" }{ "_id" : ObjectId("55c211a8d9c7fa428406b569"), "name" : "user6" }////////////////////////////////////////////////////只能存5条数据   再多插入  新的数据会取代旧的数据 //删除一个集合 数据库> show tables;c1c2system.indexes> db.c1.drop();true> show tables;c2system.indexes> db;               test> show dbs;  admin   (empty)local   (empty)test    0.0625GB> db.dropDatabase(); { "dropped" : "test", "ok" : 1 }> show dbs;admin   (empty)local   (empty)查看索引信息db.c1.getIndexKeys();[ { "_id" : 1 } ]> db.c1.getIndexes(); 详细查看[        {                "name" : "_id_",                "ns" : "test.c1",                "key" : {                        "_id" : 1                },                "v" : 0        }]> db.c1.find({'name':'user5'}).explain();     发现是全表扫描{        "cursor" : "BasicCursor",        "nscanned" : 10,        "nscannedObjects" : 10,        "n" : 1,        "millis" : 0,        "nYields" : 0,        "nChunkSkips" : 0,        "isMultiKey" : false,        "indexOnly" : false,        "indexBounds" : {        }}建立普通索引> db.c1.ensureIndex({name:1});> db.c1.getIndexKeys();[ { "_id" : 1 }, { "name" : 1 } ]   1为升序   -1降序 当数据量比较大时可以 加上｛'background':true｝在后台进行唯一索引  {unique:true}> db.c1.getIndexKeys();[ { "_id" : 1 }, { "name" : 1 } ]> db.c1.ensureIndex({age:1},{unique:true})> db.c1.getIndexKeys();[ { "_id" : 1 }, { "name" : 1 }, { "age" : 1 } ]删除指定索引> db.c1.dropIndex({age:1});{ "nIndexesWas" : 3, "ok" : 1 }删除所有索引> db.c1.dropIndexes();{        "nIndexesWas" : 2,        "msg" : "non-_id indexes dropped for collection",        "ok" : 1}> db.c1.getIndexKeys();[ { "_id" : 1 } ]慢查询日志0 - 不开启1 - 记录慢查询命令  （默认大于100ms)2 - 记录所有命令 > db.getProfilingLevel();0> db.setProfilingLevel(1,1000);   设置1s 就记录慢查询{ "was" : 0, "slowms" : 100, "ok" : 1 }// 发现毫秒数没有改过来  可以通过启动的时候更改    mongod -h    下有  --profile arg    0=off 1=slow, 2=all     --slowms arg (=100)> db.getProfilingLevel();      1> mongostat  监控mongodb  备份  <pre name="code" class="plain">// -d 数据库  -o  备份目录   如果不指定备份目录则在当前目录下创建dump的文件夹     -c  可指定到处具体哪个集合

[root@localhost bin]# ./mongodump -d test -o /tmp/
connected to: 127.0.0.1
DATABASE: test   to     /tmp/test
        test.c1 to /tmp/test/c1.bson
                 11 objects
        test.system.indexes to /tmp/test/system.indexes.bson
                 5 objects
        test.fs.files to /tmp/test/fs.files.bson
                 0 objects
        test.fs.chunks to /tmp/test/fs.chunks.bson
                 0 objects
        test.system.profile to /tmp/test/system.profile.bson
                 0 objects

还原
[root@localhost mongodb]# ./bin/mongorestore -d test /tmp/test/
connected to: 127.0.0.1
Fri Aug  7 01:36:17 /tmp/test/fs.files.bson
Fri Aug  7 01:36:17      going into namespace [test.fs.files]
Fri Aug  7 01:36:17 file /tmp/test/fs.files.bson empty, skipping
Fri Aug  7 01:36:17 /tmp/test/fs.chunks.bson
Fri Aug  7 01:36:17      going into namespace [test.fs.chunks]
Fri Aug  7 01:36:17 file /tmp/test/fs.chunks.bson empty, skipping
Fri Aug  7 01:36:17 /tmp/test/system.profile.bson
Fri Aug  7 01:36:17      skipping
Fri Aug  7 01:36:17 /tmp/test/c1.bson
Fri Aug  7 01:36:17      going into namespace [test.c1]
Fri Aug  7 01:36:17      11 objects found
Fri Aug  7 01:36:17 /tmp/test/system.indexes.bson
Fri Aug  7 01:36:17      going into namespace [test.system.indexes]
Fri Aug  7 01:36:17 { name: "_id_", ns: "test.c1", key: { _id: 1 }, v: 0 }
Fri Aug  7 01:36:18 { name: "_id_", ns: "test.fs.files", key: { _id: 1 }, v: 0 }
Fri Aug  7 01:36:18 { ns: "test.fs.files", key: { filename: 1 }, name: "filename_1", v: 0 }
Fri Aug  7 01:36:18 { name: "_id_", ns: "test.fs.chunks", key: { _id: 1 }, v: 0 }
Fri Aug  7 01:36:18 { ns: "test.fs.chunks", key: { files_id: 1, n: 1 }, name: "files_id_1_n_1", v: 0 }
Fri Aug  7 01:36:18      5 objects found