Обсуждение: Re: pgsql: Further tweaking of print_aligned_vertical().
<p dir="ltr"><br /> On 1 Dec 2015 19:48, "Tom Lane" <<a href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>> wrote:<br/> ><br /> > In passing, avoid possible calculation of log10(0). Probably that's<br /> > harmless, giventhe lack of field complaints, but it seems risky:<br /> > conversion of NaN to an integer isn't well defined.<p dir="ltr">AmI going to have to fire up the emulator again?
Greg Stark <stark@mit.edu> writes:
> On 1 Dec 2015 19:48, "Tom Lane" <tgl@sss.pgh.pa.us> wrote:
>> In passing, avoid possible calculation of log10(0). Probably that's
>> harmless, given the lack of field complaints, but it seems risky:
>> conversion of NaN to an integer isn't well defined.
> Am I going to have to fire up the emulator again?
No, 'cause I fixed it ;-). I initially thought that the case might
be unreachable, but it isn't: you can get there with cont->nrows == 0
if you have FETCH_SIZE set and the resultset size is an exact multiple
of FETCH_SIZE.
While poking at that, though, I ran into yet another bug in this code:
regression=# \pset format wrapped
Output format is wrapped.
regression=# \x
Expanded display is on.
regression=# select repeat('xyzzy',22) from generate_series(1,25);
-[ RECORD 1 ]------------------------------------------------------------------
repeat | xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy.
|.xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy
-[ RECORD 2 ]------------------------------------------------------------------
repeat | xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy.
|.xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy
.. etc etc ...
regression=# \set FETCH_COUNT 2
regression=# select repeat('xyzzy',22) from generate_series(1,25);
-[ RECORD 1 ]-------------------------------------------------------------------
---------------------------------------
repeat | xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyx
yzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy
-[ RECORD 2 ]-------------------------------------------------------------------
---------------------------------------
repeat | xyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyx
yzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzyxyzzy
.. etc etc ...
That is, wrap width determination is broken the moment you set FETCH_SIZE.
The reason seems to be this ugly kluge in ExecQueryUsingCursor():
else if (pset.queryFout == stdout && !did_pager) { /* * If query requires multiple
resultsets, hack to ensure that * only one pager instance is used for the whole mess */
pset.queryFout= PageOutput(100000, &(my_popt.topt)); did_pager = true; }
After we have run that code, pset.queryFout is no longer pointing at
stdout, which breaks every single one of the "fout == stdout" tests in
print.c. It'd be all right if those tests knew that they were dealing
with an is_pager situation, but they don't because that critical piece of
information is not passed down to printQuery(). I think we could probably
fix this by making is_pager an additional argument of printQuery() and its
relevant subroutines.
regards, tom lane
On Wed, Dec 2, 2015 at 01:16:09AM +0000, Greg Stark wrote: > > On 1 Dec 2015 19:48, "Tom Lane" <tgl@sss.pgh.pa.us> wrote: > > > > In passing, avoid possible calculation of log10(0). Probably that's > > harmless, given the lack of field complaints, but it seems risky: > > conversion of NaN to an integer isn't well defined. > > Am I going to have to fire up the emulator again? Greg's lightning talk in Vienna about how he got the emulator working was priceless. I know he posted the VAX results, but how he got them was amazing. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Roman grave inscription +
On Fri, Jan 1, 2016 at 6:41 AM, Bruce Momjian <bruce@momjian.us> wrote: > On Wed, Dec 2, 2015 at 01:16:09AM +0000, Greg Stark wrote: >> >> On 1 Dec 2015 19:48, "Tom Lane" <tgl@sss.pgh.pa.us> wrote: >> > >> > In passing, avoid possible calculation of log10(0). Probably that's >> > harmless, given the lack of field complaints, but it seems risky: >> > conversion of NaN to an integer isn't well defined. >> >> Am I going to have to fire up the emulator again? > > Greg's lightning talk in Vienna about how he got the emulator working > was priceless. I know he posted the VAX results, but how he got them > was amazing. +1. The work of a pure hacker. -- Michael
Michael Paquier <michael.paquier@gmail.com> writes:
> On Fri, Jan 1, 2016 at 6:41 AM, Bruce Momjian <bruce@momjian.us> wrote:
>> Greg's lightning talk in Vienna about how he got the emulator working
>> was priceless. I know he posted the VAX results, but how he got them
>> was amazing.
> +1. The work of a pure hacker.
Is this available online anywhere?
regards, tom lane
On Mon, Jan 4, 2016 at 3:22 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > Michael Paquier <michael.paquier@gmail.com> writes: >> On Fri, Jan 1, 2016 at 6:41 AM, Bruce Momjian <bruce@momjian.us> wrote: >>> Greg's lightning talk in Vienna about how he got the emulator working >>> was priceless. I know he posted the VAX results, but how he got them >>> was amazing. > >> +1. The work of a pure hacker. > > Is this available online anywhere? Arg, actually it is not: https://wiki.postgresql.org/wiki/PostgreSQL_Conference_Europe_Talks_2015 Greg could you add it there? -- Michael
On Mon, Jan 4, 2016 at 6:24 AM, Michael Paquier <michael.paquier@gmail.com> wrote: > Arg, actually it is not: > https://wiki.postgresql.org/wiki/PostgreSQL_Conference_Europe_Talks_2015 > Greg could you add it there? No, apparently that page is restricted to only some users. I used plenty of images I pulled off the net without regard for copyright so I hesitated to put it up. I suppose that's par for the course with these kinds of presentations. In any case it was just a quick lightning talk I threw together to describe a few days of mostly waiting around for builds to finish. Here are the two lightning talks on Google: VAX (simh): https://docs.google.com/presentation/d/1PG-bMU4WiS1pjtBwRvH4cE-nN9y5gj8ZLCO7KMrlvYg/view Fuzzer: https://docs.google.com/presentation/d/12Dd9Bhcugkdi2w0ye4T1fy9ccjconJEz9cNthdeyH7k/view -- greg
Greg Stark <stark@mit.edu> writes: > I used plenty of images I pulled off the net without regard for > copyright so I hesitated to put it up. I suppose that's par for the > course with these kinds of presentations. In any case it was just a > quick lightning talk I threw together to describe a few days of mostly > waiting around for builds to finish. Here are the two lightning talks > on Google: > VAX (simh): > https://docs.google.com/presentation/d/1PG-bMU4WiS1pjtBwRvH4cE-nN9y5gj8ZLCO7KMrlvYg/view > Fuzzer: > https://docs.google.com/presentation/d/12Dd9Bhcugkdi2w0ye4T1fy9ccjconJEz9cNthdeyH7k/view Very cool, thanks! regards, tom lane
On Mon, Jan 4, 2016 at 6:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> VAX (simh): >> https://docs.google.com/presentation/d/1PG-bMU4WiS1pjtBwRvH4cE-nN9y5gj8ZLCO7KMrlvYg/view > >> Fuzzer: >> https://docs.google.com/presentation/d/12Dd9Bhcugkdi2w0ye4T1fy9ccjconJEz9cNthdeyH7k/view > > Very cool, thanks! Incidentally, I did boot up the simulator again the other day because I had had an idea for how we might get the regression tests to pass. However the idea didn't pan out. I thought maybe we could compile just float.c with -msoft-float so that the backend used VAX floats and the user datatype was represented by IEEE floats. I'm sure there are a few places where we assume we can convert one to the other but I was hoping it would be few enough to be manageable to fix up. I wasn't sure how feasible it was to have a mixed build at all and I was going to experiment. However gcc doesn't support -msoft-float on VAX. Apparently -msoft-float is an implemented by the architecture backend rather than as a portable general purpose feature :( -- greg
On Mon, Jan 4, 2016 at 01:18:02PM -0500, Tom Lane wrote: > Greg Stark <stark@mit.edu> writes: > > I used plenty of images I pulled off the net without regard for > > copyright so I hesitated to put it up. I suppose that's par for the > > course with these kinds of presentations. In any case it was just a > > quick lightning talk I threw together to describe a few days of mostly > > waiting around for builds to finish. Here are the two lightning talks > > on Google: > > > VAX (simh): > > https://docs.google.com/presentation/d/1PG-bMU4WiS1pjtBwRvH4cE-nN9y5gj8ZLCO7KMrlvYg/view > > > Fuzzer: > > https://docs.google.com/presentation/d/12Dd9Bhcugkdi2w0ye4T1fy9ccjconJEz9cNthdeyH7k/view > > Very cool, thanks! No, you need to see the video! It was amazing. I couldn't believe what I was hearing. I was like "YOU DID WHAT!" Unfortunately, I don't think it was recorded. :-( -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Roman grave inscription +