four minor proposals for 9.5

Hello

I wrote a few patches, that we use in our production. These patches are
small, but I hope, so its can be interesting for upstream:

1. cancel time - we log a execution time cancelled statements

2. fatal verbose - this patch ensure a verbose log for fatal errors. It
simplify a investigation about reasons of error.

3. relation limit - possibility to set session limit for maximum size of
relations. Any relation cannot be extended over this limit in session, when
this value is higher than zero. Motivation - we use lot of queries like
CREATE TABLE AS SELECT .. , and some very big results decreased a disk free
space too much. It was high risk in our multi user environment. Motivation
is similar like temp_files_limit.

4. track statement lock - we are able to track a locking time for query and
print this data in slow query log and auto_explain log. It help to us with
lather slow query log analysis.

Do you thinking so these patches can be generally useful?

Regards

Pavel