问题
I have about 200MB of data stored in a S3 document collection (the highest one). Each document is about 300KB in size.
But when I ran my query, I am surprised to see that it requires 7245.81 RUs. Because S3 is at 2500 RUs/Second, this performance won't scale for my application.
I just want to ask if I am doing anything wrong and if there is anything that I can do to improve it?
My query is like this:
SELECT item.Id,item.Priority, va.something, wa.something... 11 fields in total
FROM model.Item item
JOIN va in item.Content.Children
JOIN wa in va.Children
WHERE item.State != 5
I am using "Range" as the index type. Would that impact the performance of this query?
回答1:
Queries using != will require a scan, since all index entries have to be looked up to eliminate the values that are not equal to 5. This will lead to a high RUs. Whenever possible, please try rewriting the query as an equality or a range query.
- If the number of possible values of item.State is limited, e.g., 1-10, then you can enumerate the valid values using IN, i.e., item.State IN (1,2,3,4,6,7,8,9,10)
- If that's not possible, the please use ranges e.g., item.State > 5 OR item.State < 5 like suggested by Larry above.
Hope this helps. Please email me at arramac at microsoft dot com in case you'd like to discuss in more detail.
来源：https://stackoverflow.com/questions/30541280/documentdb-query-requires-unexpected-high-rus