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1. mongos> db.testmongo.ensureIndex({'age':1,'name':1},{"unique":1})
   
2. {
   
3.         "raw" : {
   
4.                 "shard1/172.31.32.223:27001,172.31.35.47:27001,172.31.37.105:27001" : {
   
5.                         "createdCollectionAutomatically" : false,
   
6.                         "numIndexesBefore" : 1,
   
7.                         "ok" : 0,
   
8.                         "errmsg" : "cannot create unique index over { age: 1.0, name: 1.0 } with shard key pattern { _id: 1.0 }",
   
9.                         "code" : 67,
   
10.                         "codeName" : "CannotCreateIndex",
    
11.                         "$gleStats" : {
    
12.                                 "lastOpTime" : {
    
13.                                         "ts" : Timestamp(1529656402, 42),
    
14.                                         "t" : NumberLong(6)
    
15.                                 },
    
16.                                 "electionId" : ObjectId("7fffffff0000000000000006")
    
17.                         }
    
18.                 },
    
19.                 "shard2/172.31.32.223:27002,172.31.35.47:27002,172.31.37.105:27002" : {
    
20.                         "createdCollectionAutomatically" : true,
    
21.                         "numIndexesBefore" : 1,
    
22.                         "numIndexesAfter" : 2,
    
23.                         "ok" : 1,
    
24.                         "$gleStats" : {
    
25.                                 "lastOpTime" : {
    
26.                                         "ts" : Timestamp(1529656406, 2),
    
27.                                         "t" : NumberLong(7)
    
28.                                 },
    
29.                                 "electionId" : ObjectId("7fffffff0000000000000007")
    
30.                         }
    
31.                 },
    
32.                 "shard3/172.31.32.223:27003,172.31.35.47:27003,172.31.37.105:27003" : {
    
33.                         "createdCollectionAutomatically" : true,
    
34.                         "numIndexesBefore" : 1,
    
35.                         "numIndexesAfter" : 2,
    
36.                         "ok" : 1,
    
37.                         "$gleStats" : {
    
38.                                 "lastOpTime" : {
    
39.                                         "ts" : Timestamp(1529656406, 2),
    
40.                                         "t" : NumberLong(6)
    
41.                                 },
    
42.                                 "electionId" : ObjectId("7fffffff0000000000000006")
    
43.                         }
    
44.                 }
    
45.         },
    
46.         "code" : 67,
    
47.         "ok" : 0,
    
48.         "errmsg" : "{ shard1/172.31.32.223:27001,172.31.35.47:27001,172.31.37.105:27001: \"cannot create unique index over { age: 1.0, name: 1.0 } with shard key pattern { _id: 1.0 }\" }"
    
49. }
    
50. mongos> db.testmongo.ensureIndex({'_id':1,'age':1,'name':1},{"unique":1})
    
51. {
    
52.         "raw" : {
    
53.                 "shard1/172.31.32.223:27001,172.31.35.47:27001,172.31.37.105:27001" : {
    
54.                         "createdCollectionAutomatically" : false,
    
55.                         "numIndexesBefore" : 1,
    
56.                         "numIndexesAfter" : 2,
    
57.                         "ok" : 1,
    
58.                         "$gleStats" : {
    
59.                                 "lastOpTime" : {
    
60.                                         "ts" : Timestamp(1529656437, 1),
    
61.                                         "t" : NumberLong(6)
    
62.                                 },
    
63.                                 "electionId" : ObjectId("7fffffff0000000000000006")
    
64.                         }
    
65.                 },
    
66.                 "shard2/172.31.32.223:27002,172.31.35.47:27002,172.31.37.105:27002" : {
    
67.                         "createdCollectionAutomatically" : false,
    
68.                         "numIndexesBefore" : 2,
    
69.                         "numIndexesAfter" : 3,
    
70.                         "ok" : 1,
    
71.                         "$gleStats" : {
    
72.                                 "lastOpTime" : {
    
73.                                         "ts" : Timestamp(1529656437, 1),
    
74.                                         "t" : NumberLong(7)
    
75.                                 },
    
76.                                 "electionId" : ObjectId("7fffffff0000000000000007")
    
77.                         }
    
78.                 },
    
79.                 "shard3/172.31.32.223:27003,172.31.35.47:27003,172.31.37.105:27003" : {
    
80.                         "createdCollectionAutomatically" : false,
    
81.                         "numIndexesBefore" : 2,
    
82.                         "numIndexesAfter" : 3,
    
83.                         "ok" : 1,
    
84.                         "$gleStats" : {
    
85.                                 "lastOpTime" : {
    
86.                                         "ts" : Timestamp(1529656437, 1),
    
87.                                         "t" : NumberLong(6)
    
88.                                 },
    
89.                                 "electionId" : ObjectId("7fffffff0000000000000006")
    
90.                         }
    
91.                 }
    
92.         },
    
93.         "ok" : 1
    
94. }

已经被shard的collection 唯一索引的前缀必须是分片健

文章名称：【Mongo】mongosshard唯一索引的问题-创新互联
文章出自：http://chengdu.cdxwcx.cn/article/pcgsi.html