The function IDatabase::insertSelect of the database abstraction layer does not have a query builder replacement.

• Add InsertQueryBuilder::select and take a SelectQueryBuilder there
• Duplicate the (relevant) functions from SelectQueryBuilder to InsertQueryBuilder and checks, that the right mode is used
• Create a new Query Builder
• Deprecate and remove the function - It could be replaced with explicit select and insert with proper batching, but that would transfer all database from server to client to server.

Usage: https://codesearch.wmcloud.org/search/?q=%5CbinsertSelect%5Cb&files=&excludeFiles=&repos=

In deployed code:

• In core it is used on upload and file deletion
• Flow on insert of new threads
• SecurePoll on edit vote list
• Translate on new revisions
• Wikibase - tests only