Do Idle Snowflake Connections Use Cloud Services Credits?

Question

Motivation | Suppose one wanted to execute two SQL queries against a Snowflake DB, ~20 minutes apart.

Optimization Problem | Which would cost fewer cloud services credits:

1. Re-using one connection, and allowing that connection to idle in the interim.
2. Connecting once per query.

The documentation indicates that authentication incurs cloud services credit usage, but does not indicate whether idle connections incur credit usage.

Question | Does anyone know whether idle connections incur cloud services credit usage?

Answer 1

Snowflake connections are stateless. They do not occupy a resource, and they do not need to keep the TCP/IP connection alive like other database connections.

Therefore idle connections do not consume any the Cloud Services Layer credits unless you enable "CLIENT_SESSION_KEEP_ALIVE".

https://docs.snowflake.com/en/sql-reference/parameters.html#client-session-keep-alive

When you set CLIENT_SESSION_KEEP_ALIVE, the client will update the token for the session (default value is 1 hour).

https://docs.snowflake.com/en/sql-reference/parameters.html#client-session-keep-alive-heartbeat-frequency

As Peter mentioned, the CSL usage up to 10% of daily warehouse usage is free, so refreshing the tokens will not cost you anything in practice.

About your approaches: I do not know how many queries you are planning to run daily, but creating a new connection for each query can be a performance killer. For costs perspective, idle connection will do max 24 authorization requests on a day, so if you are planning to run more than 24 queries on a day, I suggest you to pick the first approach.

Answer 2

Approach 1 will incur less cloud services usage, but more data transfer charges (to keep the connection alive). Only the Auth event incurs cloud services usage.

Approach 2 will incur more cloud services usage, but less data transfer charges.

However, the amount of cloud services usage or data transfer charges are extremely small in either case.

Note - any cloud services used (up to 10% of daily warehouse usage) are free, whereas there is no free bandwidth allocation, so using #2 may save you a few pennies.

Answer 3

Even if idle connections do not cost anything in the Cloud Services respect, is your warehouse running with idle connections hence giving you other costs to consider? I am guessing there's more factors to consider overall which you can speak to your Snowflake Account Team to discuss. Not trying to dodge your question, but trying to give a more wholesome answer!

In general, the Cloud Services costs are typically on the lower side compared to your other costs. Here are the main drivers for cloud service costs and how to minimalize them: https://community.snowflake.com/s/article/Cloud-Services-Billing-Update-Understanding-and-Adjusting-Usage

The best advice you may get is to test your connections/workflows and compare the costs over time. The overall costs are going to depend on several factors. Even if there's a difference in costs between two workflows, you may still have to analyze the cost/output ratio and your business needs to determine if it's worth the savings.