mariadb-columnstore-engine/docs/WFS_checkWindowFunction.md

Statements:

• WFS adds extra aux columns into projection.
• WFS sorts using the outer ORDER BY key column list()

jobInfo.windowDels is used as a temp storage to pass unchanged list of jobInfo.deliveredCols(read as projection list of delivered cols) through WFS if there is no GB/DISTINCT involved. GB/DISTINCT can clean the list up on their own.

This method might implicitly add GB column in case of aggregates over WF and w/o explicit GROUP BY. This is disabled in WFS::AddSimpleColumn

SELECT min(fist_value(i) partition over i) from tab1;