使用 java sdk 从具有散列范围架构的给定散列键查询 DynamoDB 中的所有项目
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Query all items in DynamoDB from a given hash key with a hash-range schema using java sdk
提问by mnewton
EDIT:I was actually incorrect. I was querying the table when I meant to query an index which explains my error. Vikdor's solution is a valid one though.
编辑：我实际上是不正确的。当我打算查询解释我的错误的索引时，我正在查询表。不过，Vikdor 的解决方案是有效的。
ORIGINAL:I have a table with a Hash-Range key schema in DynamoDB. I need to be able to get all items associated with a specific hash key but it seems to require a range key condition. My issue is I want EVERY range key but there is no wildcard option. As of right now my range key is a string and the only way I could think to do this is by querying all range keys greater or equal to the smallest ascii characters I can use since the documentation says it sorts based on ascii character values.
原文：我在 DynamoDB 中有一个带有 Hash-Range 键架构的表。我需要能够获取与特定哈希键关联的所有项目，但它似乎需要范围键条件。我的问题是我想要每个范围键，但没有通配符选项。截至目前，我的范围键是一个字符串，我能想到的唯一方法是查询大于或等于我可以使用的最小 ascii 字符的所有范围键，因为文档说它基于 ascii 字符值进行排序。
I looked into scanning but it appears that simply will read the entire table which is NOT an option.
我研究了扫描，但似乎只会读取整个表格，这不是一个选项。
Is there any better way to query for all values of a hash key or can anyone confirm that using the method with the ascii character will work?
有没有更好的方法来查询哈希键的所有值，或者任何人都可以确认使用带有 ascii 字符的方法是否有效？
回答by Vikdor
but it seems to require a range key condition.
但它似乎需要一个范围键条件。
This doesn't sound to be true.
这听起来不像是真的。
I use DynamoDBMapperand use DynamoDBQueryExpressionto query all the records with a given HashKey as follows:
我使用DynamoDBMapper并使用DynamoDBQueryExpression查询具有给定 HashKey 的所有记录，如下所示：
DynamoDBQueryExpression<DomainObject> query =
new DynamoDBQueryExpression<DomainObject>();
DomainObject hashKeyValues = new DomainObject();
hashKeyValues.setHashKey(hashKeyValue);
query.setHashKeyValues(hashKeyValues);
// getMapper() returns a DynamoDBMapper object with the appropriate
// AmazonDynamoDBClient object.
List<DomainObject> results = getMapper().query(query);
HTH.
哈。
回答by Max
You can use DynamoDB's query API, which allows you to query the database based conditional expressions using the hash/range keys. You can see examples of the API here. Here is a relevant example:
您可以使用 DynamoDB 的查询 API，它允许您使用哈希/范围键查询基于数据库的条件表达式。您可以在此处查看 API 示例。这是一个相关的例子：
ItemCollection<QueryOutcome> items = table.query("theHashFieldName", "theHashFieldToQuery");
You can also query using more complex expressions. E.g.:
您还可以使用更复杂的表达式进行查询。例如：
DynamoDB dynamoDB = new DynamoDB(
new AmazonDynamoDBClient(new ProfileCredentialsProvider()));
Table table = dynamoDB.getTable("TableName");
QuerySpec spec = new QuerySpec()
.withKeyConditionExpression("Id = :v_id")
.withValueMap(new ValueMap()
.withString(":v_id", "TheId"));
ItemCollection<QueryOutcome> items = table.query(spec);
Iterator<Item> iterator = items.iterator();
Item item = null;
while (iterator.hasNext()) {
item = iterator.next();
System.out.println(item.toJSONPretty());
}
