At 13:49 16/03/01 -0500, Jan Wieck wrote:
>
> Similar problem as with shared memory - size. If a long
> running backend of a multithousand table database needs to
> send access stats per table - and had accessed them all up to
> now - it'll be alot of wasted bandwidth.
Not if you only send totals for individual counters when they change; some
stats may never be resynced, but for the most part it will work. Also, does
Unix allow interrupts to occur as a result of data arrivibg in a pipe? If
so, how about:
- All backends to do *blocking* IO to collector.
- Collector to receive an interrupt when a message arrives; while in the
interrupt it reads the buffer into a local queue, and returns from the
interrupt.
- Main line code processes the queue and writes it to a memory mapped file
for durability.
- If collector dies, postmaster starts another immediately, which slears
the backlog of data in the pipe and then remaps the file.
- Each backend has its own local copy of it's counters which *possibly* to
collector can ask for when it restarts.
----------------------------------------------------------------
Philip Warner | __---_____
Albatross Consulting Pty. Ltd. |----/ - \
(A.B.N. 75 008 659 498) | /(@) ______---_
Tel: (+61) 0500 83 82 81 | _________ \
Fax: (+61) 0500 83 82 82 | ___________ |
Http://www.rhyme.com.au | / \| | --________--
PGP key available upon request, | /
and from pgp5.ai.mit.edu:11371 |/
