Slow bulk insert for table with many indexes

Question

I try to insert millions of records into a table that has more than 20 indexes.

In the last run it took more than 4 hours per 100.000 rows, and the query was cancell

Answer 1

As noted by another answer disabling indexes will be a very good start.

4 hours per 100.000 rows [...] The inserts are wrapped in a transaction per 100.000 rows.

You should look at reducing the number, the server has to maintain a huge amount of state while in a transaction (so it can be rolled back), this (along with the indexes) means adding data is very hard work.

Why not wrap each insert statement in its own transaction?

Also look at the nature of the SQL you are using, are you adding one row per statement (and network roundtrip), or adding many?