Explain Analyze (Rollback off) Suggestion

The recent discussion about EXPLAIN and the possible inclusion of
default-specifying GUCs raised a behavior that I did not fully appreciate
nor find to be self-evident. Running EXPLAIN ANALYZE results in any
side-effects of the explained and analyzed statement being permanently
written to the current transaction - which is in many cases is implicitly
immediately committed unless the user takes care otherwise. This seems
like an implementation expedient behavior but an unfriendly default. It
doesn't seem unreasonable for a part-time dba to expect an explain outcome
to always be non-persistent, even in ANALYZE mode since the execution of
that command could be done in a transaction (or savepoint...) and then
immediately undone before sending the explain output to the client.

I'm against having a GUC that implicitly triggers an ANALYZE version of the
EXPLAIN command. I also think that it would be worth the effort to try and
make EXPLAIN ANALYZE default to using auto-rollback behavior. Overriding
that default behavior could be done on a per command basis by specifying
the option "ROLLBACK off". With the new GUCs users that find themselves in
the situation of needing a non-permanent outcome across multiple commands
could then get back to the less safe behavior by setting the corresponding
GUC to off in their session. I won't pretend to have any idea how often
that would be useful - especially as it would depend upon whether the
auto-savepoint idea is workable or whether the client has to be outside of
a transaction in order for the rollback limited behavior to work.

I cannot make this happen even if there is interest but it seems like a
good time to bring up the idea.

David J.