问题
I have a read operation that reads a lot of records from a DocumentDb collection and when executed it will run for a long time. I am writing a stored procedure to move that query to the server-side. I understand that documentdb stored procedures have a execution cap of 5 seconds. What i wanna know is that in a read operation what happens when the query execution hits that time limit. Can i add some kind of a retry logic to continue after some time or will i have to do the read from the beginning?
回答1:
This is not a problem if you follow this simple pattern when writing your stored procedures and you keep calling the stored procedure until continuation comes back null.
The key help here is that you are given some buffer beyond the 5 seconds to wrap up your stored procedure before it's forcedly shut down. Whenever the sproc is about to be shut down, the most recent database operation will return false instead of true. DocumentDB gives you enough time to process the last batch returned.
For read/query operations (example countDocuments), the key element to the recommended pattern is to store the continuation token for your read/query operation in the body that's returned from your stored procedure. You can set the body as many times as you want. Only the last one will be returned when the stored procedure either exist gracefully when resource limits are reached or whenever the stored procedure's job is done.
For write operations (example createVariedDocuments), documentdb-utils still looks at the continuation that's returned to decide if the sproc has finished its work except in this case, it won't be a read/query continuation and its value doesn't matter. It's simply an indicator for whether or not you need to call the sproc again. That's why I set it to "Value does not matter" in my example. Anything other than null would work.
Key off of the continuation that's returned from the stored procedure execution to decide whether or not to call it again. Documentdb-utils will automatically keep calling your stored procedure until continuation comes back null but you can implement this yourself. Documentdb-utils also includes a number of example sprocs that implement this pattern for you to riff off of. Documentdb-lumenize utilizes this pattern to the nth degree to implement an aggregation engine running inside of a sproc.
Disclosure: I'm the author of documentdb-utils and documentdb-lumenize.
来源：https://stackoverflow.com/questions/34656072/what-happens-when-5-second-execution-time-limit-exceeds-in-azure-documentdb-stor