Обсуждение: Linux/Alpha Regression tests....

Ok, here is a run down on the regression tests for
pgsql snapshot (09271998) on Linux/Alpha:

int2 .. failed - Difference in error messages. (ok)
int4 .. failed - Wrapped number when should have errored. (ok)
float4 .. failed - Overflow and underflow numbers rounded to inf and                  9.99999E-40 when error message
shouldhave resulted.       (ok)
 
float8 .. failed - Same as above. (ok)
numerology .. failed - First same as int4, then a backend failure.                      (Problem?)
geometry .. failed - Off by one in nth decimal place. (ok)
datetime .. failed - Problems with adding time to 'today'. (Problem!)
reltime .. failed - More time calculation failures. (Problem!)
abstime .. failed - All dates a long way off, by a few hundred years.                   (PROBLEM!)
tinterval .. failed - Same as above. (PROBLEM!)
horology .. failed - Same as above. (PROBLEM!)
select_having .. failed - Backend failure, probably memory violation.                         (Problem)
union .. failed - Same as int4. (ok)
random .. failed - Failure on a type and oid, wierd. (Problem?)
misc .. failed - More wierd errors. :( (Problem?)
It appears most of the problems are concentrated in the datetime
code, and the rest of the problems are cascade failures from trying to use
the faulty datetime functions for more extensive tests. There are a few
other problems (i.e. select_having), but I feel that the datetime stuff
needs to be sorted out first.I have tried to figure out what is up with the datetime code many
times, but always ended in a dead end. Any test programs I write to see if
I can isolate the problem work fine. Any attempts at debugging are
fruitless as gdb is not 100% stable on Linux/Alpha and gets lost sometimes
(returning random values for memory address! :( ).What I have been able to track down that any call to localtime()
library call is returning a date at some point in the year 2136! The
system clock is correct. localtime() does conversion between time formats
and somewhere it is getting its feet stepped on. Date time data going in
is fine, but coming out it is scrambled. Test programs that just run data
through localtime() work just fine. Also, this only seems to happen when 'today' (if I
remember correctly) is used for datetime input. Actual dates seem to work
just fine though.The biggest trouble in finding this bug is how "complex" the
datetime code is... Actually after hacking at it for a few hours (with no
success) I have other words to describe it, but I will refrain. :) Might
some one explain to me what exactly is happening in the datetime code so I
might have some idea what is going on. I am relatively good at C, but even
this tests my skills pretty good. As I find time, I will work further to resolve these problems. If
any one else has any ideas or advice on how to solve this problem, please
send them my way!
PS. If some of this appears vague, it is. I have not had time to
hack recently on pgsql thanks to too much schoolwork. :( Just with the 6.4
release going out soon, I though I better see what help I could find...
PPS. Patch for pgsql snapshots to compile on Linux/Alpha are
coming shortly.

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|   "For to me to live is Christ, and to die is gain."                     |
|                                            --- Philippians 1:21 (KJV)    |
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|  Ryan Kirkpatrick  |  Boulder, Colorado  | rkirkpat@nag.cs.colorado.edu  |
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|               http://www-ugrad.cs.colorado.edu/~rkirkpat/                |
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> The biggest trouble in finding this bug is how "complex" the
> datetime code is... Actually after hacking at it for a few hours (with 
> no success) I have other words to describe it, but I will refrain.

I'll assume it would be a compliment :) I was happy with how simple I
was able to make the code. Date/time stuff ain't easy.

I'm guessing that the problem is in one of two areas:

1) the configure/build process is confused as to what kind of time
support you have on your system. There are two styles of local time
conversion interfaces on Unix systems: one which uses global variables
to return info on time zones, and one which returns that info as part of
the tz structure. The third type, which is pretty much no timezone
support, is probably not relevant, though if your system is really
confused you should eliminate that as a possibility. The second type is
reentrant, the first is not. It doesn't really matter which kind your
system uses because each backend is essentially single-threaded, but if
it guesses wrong on what kind of system you have then the results will
be garbage.

2) the Postgres code stomps on the global variables used for timezone
info. I think I got that resolved, but I figured I should mention it
just in case.

It is most likely that (1) is the problem. Try compiling with
"-DDATEDEBUG" specified, and see if that helps you track through the
code. Though it seems like you already know where the problem is
located, so I'd just pound on an example until you get it figured out.

Good luck.
                      - Tom