如何避免arangoDB中的重復

Question

在使用arangoDB時，有沒有“簡單”的方法來避免上傳重復文檔（使用自動生成的_key）？

Answer 1

Arango這樣做的方法是使用uniq哈希索引 。 但是，無法在整個文檔中創建它，只能創建它的一部分：

db._create("testuniq")
[ArangoCollection 25260888467, "testuniq" (type document, status loaded)]
arangosh [_system]> db.testuniq.ensureIndex({ type: "hash", fields:["uniqDocument", "uniqAttribute"], unique: true })
{ 
  "id" : "testuniq/25264886163", 
  "type" : "hash", 
  "fields" : [ 
    "uniqDocument", 
    "uniqAttribute" 
  ], 
  "selectivityEstimate" : 1, 
  "unique" : true, 
  "sparse" : false, 
  "isNewlyCreated" : true, 
  "code" : 201 
}
arangosh [_system]> db.testuniq.save({uniqDocument: {foo: "bar"}})
arangosh [_system]> db.testuniq.save({uniqDocument: {foo: "bar"}})
JavaScript exception in file 'js/client/modules/org/arangodb/arangosh.js' at 106,13: ArangoError 1210: cannot create document, unique constraint violated
!      throw error;
!            ^
stacktrace: ArangoError: cannot create document, unique constraint violated
    at Object.exports.checkRequestResult (js/client/modules/org/arangodb/arangosh.js:104:21)
    at ArangoCollection.save.ArangoCollection.insert (js/client/modules/org/arangodb/arango-collection.js:1014:12)
    at <shell command>:1:13
arangosh [_system]> db.testuniq.save({uniqAttribute: "bar"})
arangosh [_system]> db.testuniq.save({uniqAttribute: "bar"})
JavaScript exception in file 'js/client/modules/org/arangodb/arangosh.js' at 106,13: ArangoError 1210: cannot create document, unique constraint violated
!      throw error;
!            ^
stacktrace: ArangoError: cannot create document, unique constraint violated
    at Object.exports.checkRequestResult (js/client/modules/org/arangodb/arangosh.js:104:21)
    at ArangoCollection.save.ArangoCollection.insert (js/client/modules/org/arangodb/arango-collection.js:1014:12)
    at <shell command>:1:13