如何使用 DynamoDBMapper 查询具有仅具有 hashKeys 的 GSI 的 Dynamo DB [英] How to query a Dynamo DB having a GSI with only hashKeys using DynamoDBMapper

问题描述

我对 Dynamo DB 很陌生，可能这是一个非常微不足道的问题，但我浏览了 Dynamo DB 的文档和堆栈溢出问题，但我找不到一个链接来说明如何查询 GSI 的 DDB，它只有散列键，没有指定范围键.

I am very new to Dynamo DB and may be this is very trivial question, but i went through the documents of Dynamo DB and stack overflow questions but i couldnt find a single link which tells how to query DDB for GSI which has only hash key and there are no range key specified for the same.

我收到异常 Illegal query expression: No hash key condition is found in the query.

I get the exception Illegal query expression: No hash key condition is found in the query.

推荐答案

在你的 DynamoDB 注释模型对象上，你应该使用 @DynamoDBIndexHashKey(globalSecondaryIndexName = "gsiIndexName) 来表示它是一个哈希键对于 GSI:

On your DynamoDB annotated model object, you should use @DynamoDBIndexHashKey(globalSecondaryIndexName = "gsiIndexName) to signify that it is a hash key for the GSI:

@DynamoDBTable(tableName = "myTable")
public class MyTable {
    ...

    @DynamoDBIndexHashKey(globalSecondaryIndexName = "myGsi")
    public String getGsiHk() {
        return gsiHk;
    }

    ...
}

然后在DynamoDBMapper上使用query方法:

final MyTable gsiKeyObj = new MyTable();
gsiKeyObj.setGsiHk("myGsiHkValue");
final DynamoDBQueryExpression<MyTable> queryExpression = 
    new DynamoDBQueryExpression<>();
queryExpression.setHashKeyValues(gsiKeyObj);
queryExpression.setIndexName("myGsi");
queryExpression.setConsistentRead(false);   // cannot use consistent read on GSI
final PaginatedQueryList<MyTable> results = 
    mapper.query(MyTable.class, queryExpression);

这篇关于如何使用 DynamoDBMapper 查询具有仅具有 hashKeys 的 GSI 的 Dynamo DB的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！