Azure slow response times

Question

Wondering if an Azure experts out there can give me some suggestions, we have a App Service app running and have noticed that on the first few requests (even if always on is ON) it can take a very long time for response.

The below chart is what we observed ,one can see that it takes up to 2 minutes initially and then afterwards we get more reasonable response times of a few milliseconds/seconds.

How can we make sure that it ALWAYS responds quickly? As a simple test, it is not doing anything processing intensive, just a few simple DB queries to check if a key exists.

Answer 1

At the beginning (the very first few minutes) Azure SQL Databases run queries slowly due to reduce memory allocation. You can see the query plan of those queries that run slowly at first and then show good performance and you can see query plan is the same. On the first run you may see query waits are: MEMORY_ALLOCATION_EXT, IO_QUEUE_LIMIT or PAGEIOLATCH_SH.

After periods of no activity, failovers or scaling up/down tiers memory allocation may be reduced and queries may show poor performance the first few minutes.

Hope this helps