Replace-Into-vs-Insert-on-Duplicate.md

Replace into vs insert on duplicate

There’s several ways the to bulk insert or update data.

• Delete duplicate and bulk insert
  • Can’t know what to delete first if insertion is calculated and size is big, not able to put in RAM.
• Replace into
• Bulk Insert into and bulk on duplicate

There’s one problem with replace into is that it actually delete duplicate data first and insert new data, and it will trigger delete casade, which may not the sql originally want to do.

Base on this, I didn’t compare performance, besides, should be about the same.