On 24 June 2014 23:44, Tom Lane <t...@sss.pgh.pa.us> wrote: > Simon Riggs <si...@2ndquadrant.com> writes: >> Having said that, any join plan that relies upon a constraint will >> still be valid even if we drop a constraint while the plan executes >> because any new writes will not be visible to the executing join plan. > > mumble ... EvalPlanQual ?
As long as we are relaxing a constraint, we are OK if an earlier snapshot thinks its dealing with a tighter constraint whereas the new reality is a relaxed constraint. The worst that could happen is we hit an ERROR from a constraint that was in force at the start of the query, so for consistency we really should be enforcing the same constraint throughout the lifetime of the query. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers