can tell whether it is being used as an aggregate or not. This allows
such a function to avoid re-pallocing a pass-by-reference transition
value; normally it would be unsafe for a function to scribble on an input,
but in the aggregate case it's safe to reuse the old transition value.
Make int8inc() do this. This gets a useful improvement in the speed of
COUNT(*), at least on narrow tables (it seems to be swamped by I/O when
the table rows are wide). Per a discussion in early December with
Neil Conway. I also fixed int_aggregate.c to check this, thereby
turning it into something approaching a supportable technique instead
of being a crude hack.
Formerly, if such a clause contained no aggregate functions we mistakenly
treated it as equivalent to WHERE. Per spec it must cause the query to
be treated as a grouped query of a single group, the same as appearance
of aggregate functions would do. Also, the HAVING filter must execute
after aggregate function computation even if it itself contains no
aggregate functions.
the freelist, plus per-buffer spinlocks that protect access to individual
shared buffer headers. This requires abandoning a global freelist (since
the freelist is a global contention point), which shoots down ARC and 2Q
as well as plain LRU management. Adopt a clock sweep algorithm instead.
Preliminary results show substantial improvement in multi-backend situations.
adjusting values:
> But to be on the safe side, it would make sense to do something similar
> to the BSD section, and comment about older distributions maybe needing
> to manipulate /proc/kernel/* directly.
Mark Kirkwood
! authentication. Use of this environment variable is not
! recommended for security reasons (some operating systems
! allow non-root users to see process environment variables via
! <application>ps</>); instead consider using the
! <filename>~/.pgpass</> file (see <xref linkend="libpq-pgpass">).
Bruce Momjian
Neil Conway
Tom Lane