问题
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.
I get the exception Illegal query expression: No hash key condition is found in the query.
回答1:
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;
}
...
}
And then use the query
method on the DynamoDBMapper
:
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);
来源:https://stackoverflow.com/questions/30457820/how-to-query-a-dynamo-db-having-a-gsi-with-only-hashkeys-using-dynamodbmapper