问题
I'm working with data in AWS Athena, and I'm trying to match the structure of some input data. This involves a nested structure where "from" is a key. This consistently throws errors.
I've narrowed the issue down to the fact that Athena queries don't work when you try to use reserved keywords as keys in rows. The following examples demonstrate this behavior.
This simple case,
SELECT CAST(ROW(1) AS ROW("from" INTEGER)), fails with the following error:GENERIC_INTERNAL_ERROR: Unable to create class com.facebook.presto.execution.TaskInfo from JSON response: [io.airlift.jaxrs.JsonMapperParsingException: Invalid json for Java typeThis simple case runs successfully:
SELECT CAST(ROW(1) AS ROW("work" INTEGER))
The Athena documentation says to enclose reserved keywords in double quotes to use them in SELECT statements, but the examples above show that queries still fail when using keywords as keys in rows.
I know I have other options, but this way is by far the most convenient. Is there a way to use reserved keywords in this scenario?
回答1:
As Piotr mentions in a comment, this is a Presto bug and given that it was posted just days ago it's unlikely to be fixed in Athena anytime soon. When the bug is fixed in Presto it might find its way into Athena, I know the Athena team sometimes apply upstream patches even though Athena is based on an old version of Presto. This one might not be significant enough to appear on their radar, but if you open a support ticket with AWS it might happen (be sure to be clear that you don't need any workaround just report a bug, otherwise you'll have a support person spending way too much time trying to help you to turn things off and on again).
来源：https://stackoverflow.com/questions/64381706/aws-athena-row-cast-fails-when-key-is-a-reserved-keyword-despite-double-quotes