Re: Command Triggers, patch v11

I wrote:
> One thing I soon found is that it lacks support for EXPLAIN SELECT INTO.

While I'm not particularly excited about fixing PREPARE ... SELECT INTO
or CREATE RULE ... SELECT INTO, I've come to the conclusion that the
EXPLAIN case is a must-fix. Because not only is EXPLAIN SELECT INTO
broken, but so is EXPLAIN CREATE TABLE AS, and the latter functionality
is actually documented. So presumably somebody went out of their way
to make this work, at some point.

Since I've got the table-creation code moved into intorel_startup,
this doesn't look to be that painful, but it will require an API change
for ExplainOnePlan, which is slightly annoying because that's probably
in use by third-party plugins. We could either break them obviously
(by adding an explicit parameter) or break them subtly (by adding an
ExplainState field they might forget to initialize). The former seems
preferable.

regards, tom lane