数据存储查询的到期速度有多快？

Question

How fast data store query expires ? I googled but didn't find number in documentation.

Code throws:

com.google.appengine.api.datastore.DatastoreFailureException: query has expired or is invalid. Please restart it with the last cursor to read more results.

Answer 1

It's 30 seconds.

Semi-official answer was given by Google employee in their bugtracking system here .

Answer 2

A query cursor can last hours. If you're getting this error consistently in a short amount of time after performing the query for the first time, it may mean your cursor string is incorrect, or you are using the cursor with an incorrect query. (The query must be identical to the one used to generate the cursor.)

If you change the configuration of a composite index that powers a query, all existing cursors are invalidated. The docs suggest that a change to the underlying implementation (by the App Engine team) can also invalidate cursors.