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我通过Java异步驱动程序使用MongoDB 3.4 这是我的收藏索引之一：
(?: Non-capturing group. Groups multiple tokens together without creating a capture group.
. Dot. Matches any character except line breaks.
* Star. Match 0 or more of the preceding token.
)
(?: Non-capturing group. Groups multiple tokens together without creating a capture group.
\b Word boundary. Matches a word boundary position such as whitespace, punctuation, or the start/end of the string.
l Character. Matches a "l" character (char code 108).
o Character. Matches a "o" character (char code 111).
c Character. Matches a "c" character (char code 99).
a Character. Matches a "a" character (char code 97).
l Character. Matches a "l" character (char code 108).
h Character. Matches a "h" character (char code 104).
o Character. Matches a "o" character (char code 111).
s Character. Matches a "s" character (char code 115).
t Character. Matches a "t" character (char code 116).
\/ Escaped character. Matches a "/" character (char code 47).
| Alternation. Acts like a boolean OR. Matches the expression before or after the |.
l Character. Matches a "l" character (char code 108).
o Character. Matches a "o" character (char code 111).
c Character. Matches a "c" character (char code 99).
a Character. Matches a "a" character (char code 97).
l Character. Matches a "l" character (char code 108).
h Character. Matches a "h" character (char code 104).
o Character. Matches a "o" character (char code 111).
s Character. Matches a "s" character (char code 115).
t Character. Matches a "t" character (char code 116).
: Character. Matches a ":" character (char code 58).
4 Character. Matches a "4" character (char code 52).
0 Character. Matches a "0" character (char code 48).
8 Character. Matches a "8" character (char code 56).
0 Character. Matches a "0" character (char code 48).
\/ Escaped character. Matches a "/" character (char code 47).
)
( Capturing group #1. Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference.
. Dot. Matches any character except line breaks.
* Star. Match 0 or more of the preceding token.
)
有几天我遇到了异常问题，那就是我在我的数据库中遇到了这样的记录：
posts:{orders.postReqID:1, unique:1}
我不知道原因，我多次删除了这样的子文档。
然后我放了一个带posts:
{
...,
orders
[
...,
{
// Please notice there is an implicit postReqID:null
viewCount: -1,
amount: 1
}
]
}, ...
的文档来诊断问题（因为我有一个唯一的索引，它不允许为这个字段添加更多的空值）：
orders.postReqID:null这是我怀疑的查询：
{ //This is the document I inserted inside my db
...
orders:
[
{
postReqID:Null
date:0
viewCount:0
remaining:0
}
]
}
我遇到这样的错误（将该文档放入我的数据库并再次执行此查询之后）：
posts.findOneAndUpdate(
and(new Document("visits.userID", userID),
new Document("orders.postReqID", postReqID)
),
new Document("$inc",
new Document("orders.$.viewCount", 1)
.append("orders.$.remaining", -1)
)
.append("$set", new Document("orders.$.endDate", currentTime)
.append("visits.$.date", currentTime)),
(r, t) ->
{
if (t != null)
{
t.fillInStackTrace();
t.printStackTrace();
}
}
)
此异常表示此查询执行了异常更新，此查询不应执行此操作。此查询不应在com.mongodb.MongoCommandException: Command failed with error 11000: 'E11000 duplicate key error collection: ViewMember.posts index: orders.postReqID_1 dup key: { : null }' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "E11000 duplicate key error collection: ViewMember.posts index: orders.postReqID_1 dup key: { : null }", "code" : 11000, "codeName" : "DuplicateKey" }
at com.sunova.bot.MongoDBDriver$14.lambda$requestAsync$1(MongoDBDriver.java:768)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.async.client.MongoClientImpl$2$2.onResult(MongoClientImpl.java:144)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.operation.OperationHelper$ReferenceCountedReleasingWrappedCallback.onResult(OperationHelper.java:368)
at com.mongodb.operation.CommandOperationHelper$1.onResult(CommandOperationHelper.java:381)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor$1.onResult(DefaultServer.java:185)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.connection.CommandProtocol$CommandResultCallback.callCallback(CommandProtocol.java:275)
at com.mongodb.connection.ResponseCallback.onResult(ResponseCallback.java:48)
at com.mongodb.connection.ResponseCallback.onResult(ResponseCallback.java:23)
at com.mongodb.connection.DefaultConnectionPool$PooledConnection$2.onResult(DefaultConnectionPool.java:470)
at com.mongodb.connection.DefaultConnectionPool$PooledConnection$2.onResult(DefaultConnectionPool.java:464)
at com.mongodb.connection.UsageTrackingInternalConnection$3.onResult(UsageTrackingInternalConnection.java:119)
at com.mongodb.connection.UsageTrackingInternalConnection$3.onResult(UsageTrackingInternalConnection.java:115)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.connection.InternalStreamConnection.executeCallbackAndReceiveResponse(InternalStreamConnection.java:378)
at com.mongodb.connection.InternalStreamConnection.access$1700(InternalStreamConnection.java:66)
at com.mongodb.connection.InternalStreamConnection$ResponseBuffersCallback.onResult(InternalStreamConnection.java:420)
at com.mongodb.connection.InternalStreamConnection$ResponseBuffersCallback.onResult(InternalStreamConnection.java:389)
at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.onSuccess(InternalStreamConnection.java:562)
at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.access$2200(InternalStreamConnection.java:517)
at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback$ResponseBodyCallback.onResult(InternalStreamConnection.java:584)
at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback$ResponseBodyCallback.onResult(InternalStreamConnection.java:568)
at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:447)
at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:444)
at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:218)
at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:201)
at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)
at sun.nio.ch.Invoker$2.run(Invoker.java:218)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
子文档中插入任何新的子数组元素，但确实如此。是什么导致这样的？如果您查看第一个文档（在此问题的开头），您会看到orders和viewCount中有两个增量，应该完成，但插入是在{{1}中完成的此查询不是您所看到的。似乎MongoDB没有更新我想要的子数组元素，并在那里放置新元素。
答案 0 :(得分：2)
$positional运算符的使用存在冲突。
您有两个数组索引在播放visits和orders。根据{{1}}的评估顺序，它会将其解析为一个索引值。
在您的情况下，位置运算符正在根据您提供的条件解析为$and的索引值。
现在更新将使用可能没有匹配visits.userID的索引，并使用您提供的查询字段和更新字段为orders创建新条目。
答案 1 :(得分：0)
看起来您已经拥有一个具有空字段值的用户。您只需找到并删除空文档即可。如果文档没有唯一索引中索引字段的值，则通常会出现此问题，索引将为此文档存储空值。
如果您修复了错误，并且想要使用具有空值的多个文档，则可以使用稀疏索引。这是关于稀疏的解释：