dapper batch update or insert is particularly slow

[XuLinFei]

dapper batch update or insert is particularly slow

[mgravell]

Do you have any example code, time taken, and data volume, for context?

[rickyzu]

We had a similar issue recently with Dapper v2.0.78 and .Net5. We were simply trying to update 100 rows with some new data (6 or 7 columns per row). It took around 8.5 minutes running locally via visual studio. I amended the code to use Dapper.Contrib and encountered similar issues.

I eventually used Entity framework for all Inserts and Updates (update time was under a few seconds) and Dapper for MultiResult Reader.

[paaaz]

The problem why inserting/updating takes so long is described in #1071

A solution would be to modify the insert statement by expanding the "VALUES" part for each element in the collection instead of sending a single command to the DB for each element