What is better to return from SQL query to Golang array or channel?

Question

go

Hello, I'm exploring the possibilities of working with Golang. In particular, there is a question about what is more productive in the task of obtaining data from the database and sending them via the SMTP server, since there can be several hundred thousand records
1) SQL -> structure channel -> go SMTP sending routine (one letter - one goroutine )
2) SQL -> array of structures -> batch formation -> go routine sending via SMTP (a batch of letters is one gorutin)
I would be very grateful for detailed advice.

Answer 1

I don’t understand the advantages of the second method - only the difficulties in forming packs.
Here is a simple example describing this type of task https://gobyexample.ru/worker-pools.html
If there is really too much data to get in one request, you will have to use a cursor.