Before this commit, for the db with old active tasks and many projects and tasks. The report takes several hours to execute the sql view. Because we take the create date of the oldest task as the begin date of each generate_series to calculate the different group bys (day, week, month, quarter and year) until CURRENT_DATE. This commit hugely improves the performance of the sql view execution for the burndown chart report. closes odoo/odoo#72664 X-original-commit: 89726a22862cf14f7b88e130fb79ddc74bffff5e Signed-off-by: LTU-Odoo <IT-Ideas@users.noreply.github.com> Co-authored-by: Nicolas Seinlet (NSE) <nse@openerp.com> Co-authored-by: Thibault Libioulle (TLE) <tle@odoo.com> Co-authored-by: Laurent Stukkens (LTU) <ltu@odoo.com>