Aerospike 客户端具有 scanAll 方法,用于从其存储中读取所有行.我在以下代码中使用它:
Aerospike client has scanAll method for reading all rows from it's store. I use it in the folowing code:
ScanPolicy policy = new ScanPolicy();
policy.concurrentNodes = true;
policy.priority = Priority.DEFAULT;
policy.includeBinData = true;
policy.scanPercent = 100;
client.scanAll(policy, "namespaceName", "setName", new ScanCallback() {
@Override
public void scanCallback(Key key, Record record) throws AerospikeException {
STORE.put(key.userKey.toLong(), record.getValue("binName").toString());
}
});
但它以 NullPointerException
结束,因为 userKey 为空.所有其他字段都按预期有效.User key 是 Long 值,用于保存数据:
But it is finished with NullPointerException
, because userKey is null. All other fields are valid as expected. User key is the Long value, that was used for saving data:
client.put(writePolicy, new Key("namespaceName", "setName", userKey), new Bin("binName", value));
一切都很好,如果我像这样提出单个请求:
All is fine, if I do single request like this:
client.get(readPolicy, new Key("namespaceName", "setName", userKey));
可能有什么问题?为什么 userKey 为空?
What may be wrong? Why userKey is null?
Aerospike 使用 key 和 set name 生成唯一的摘要,所以它只存储摘要.
Aerospike uses key and set name to generate unique digest, So it stores only digest.
在插入一条记录时,如果您设置 writePolicy.sendKey = true
,那么 key 将被存储为记录的元数据.如果使用 writePolicy.sendKey = true
插入一条记录,那么只有你会在 scanCallback() 中获得密钥.
While inserting one record if you set writePolicy.sendKey = true
then key will be stored as metadata of record.
If one record is inserted with writePolicy.sendKey = true
then only you will get key in scanCallback().
默认 writePolicy.sendKey 为 false,所以默认 scanCallback()
获取 null 作为键.这就是为什么您的 key.userKey.toLong()
给出 NullPointerException.
By default writePolicy.sendKey is false, so by default scanCallback()
gets null as key. Thats why your key.userKey.toLong()
gives NullPointerException.
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