The initial commit tried to test them on trivial cases such as 0,
reasoning that we shouldn't hit any portability issues that way.
The buildfarm immediately proved that hope ill-founded, and anyway
it's not a great testing scheme because it doesn't prove that we're
even calling the right library function for each SQL function.
Instead, let's test them at inputs such as 1 (or something within
the valid range, as needed), so that each function should produce
a different output.
As committed, this is just about certain to show portability
failures, because it's very unlikely that every platform computes
these functions the same as mine down to the last bit. However,
I want to put it through a buildfarm cycle this way, so that
we can see how big the variations are. The plan is to add
"set extra_float_digits = -1", or whatever we need in order to
hide the variations; but first we need data.
Discussion: https://postgr.es/m/E1h3nUY-0000sM-Vf@gemulon.postgresql.org
The SQL:2016 standard adds support for the hyperbolic functions
sinh(), cosh(), and tanh(). POSIX has long required libm to
provide those functions as well as their inverses asinh(),
acosh(), atanh(). Hence, let's just expose the libm functions
to the SQL level. As with the trig functions, we only implement
versions for float8, not numeric.
For the moment, we'll assume that all platforms actually do have
these functions; if experience teaches otherwise, some autoconf
effort may be needed.
SQL:2016 also adds support for base-10 logarithm, but with the
function name log10(), whereas the name we've long used is log().
Add aliases named log10() for the float8 and numeric versions.
Lætitia Avrot
Discussion: https://postgr.es/m/CAB_COdguG22LO=rnxDQ2DW1uzv8aQoUzyDQNJjrR4k00XSgm5w@mail.gmail.com
Previously, floating-point output was done by rounding to a specific
decimal precision; by default, to 6 or 15 decimal digits (losing
information) or as requested using extra_float_digits. Drivers that
wanted exact float values, and applications like pg_dump that must
preserve values exactly, set extra_float_digits=3 (or sometimes 2 for
historical reasons, though this isn't enough for float4).
Unfortunately, decimal rounded output is slow enough to become a
noticable bottleneck when dealing with large result sets or COPY of
large tables when many floating-point values are involved.
Floating-point output can be done much faster when the output is not
rounded to a specific decimal length, but rather is chosen as the
shortest decimal representation that is closer to the original float
value than to any other value representable in the same precision. The
recently published Ryu algorithm by Ulf Adams is both relatively
simple and remarkably fast.
Accordingly, change float4out/float8out to output shortest decimal
representations if extra_float_digits is greater than 0, and make that
the new default. Applications that need rounded output can set
extra_float_digits back to 0 or below, and take the resulting
performance hit.
We make one concession to portability for systems with buggy
floating-point input: we do not output decimal values that fall
exactly halfway between adjacent representable binary values (which
would rely on the reader doing round-to-nearest-even correctly). This
is known to be a problem at least for VS2013 on Windows.
Our version of the Ryu code originates from
https://github.com/ulfjack/ryu/ at commit c9c3fb1979, but with the
following (significant) modifications:
- Output format is changed to use fixed-point notation for small
exponents, as printf would, and also to use lowercase 'e', a
minimum of 2 exponent digits, and a mandatory sign on the exponent,
to keep the formatting as close as possible to previous output.
- The output of exact midpoint values is disabled as noted above.
- The integer fast-path code is changed somewhat (since we have
fixed-point output and the upstream did not).
- Our project style has been largely applied to the code with the
exception of C99 declaration-after-statement, which has been
retained as an exception to our present policy.
- Most of upstream's debugging and conditionals are removed, and we
use our own configure tests to determine things like uint128
availability.
Changing the float output format obviously affects a number of
regression tests. This patch uses an explicit setting of
extra_float_digits=0 for test output that is not expected to be
exactly reproducible (e.g. due to numerical instability or differing
algorithms for transcendental functions).
Conversions from floats to numeric are unchanged by this patch. These
may appear in index expressions and it is not yet clear whether any
change should be made, so that can be left for another day.
This patch assumes that the only supported floating point format is
now IEEE format, and the documentation is updated to reflect that.
Code by me, adapting the work of Ulf Adams and other contributors.
References:
https://dl.acm.org/citation.cfm?id=3192369
Reviewed-by: Tom Lane, Andres Freund, Donald Dong
Discussion: https://postgr.es/m/87r2el1bx6.fsf@news-spur.riddles.org.uk
Early returns from the buildfarm say that most critters are good with
commit cbdb8b4c0, but gaur gives unexpected results with the test case
involving a float8 that's one-ULP-less-than-2^63. It appears that that
platform's version of rint() rounds that value up to 2^63 instead of
leaving it be. This is possibly a bug, and it's also possible that no
other platform anybody is using anywhere behaves likewise. Still, the
point of the test is not to insist that everybody's rint() behaves exactly
the same. Let's use two-ULPs-less-than-2^63 instead, which I've tested
to act the same on gaur as on more modern hardware.
(This is, more or less, exactly the portability issue I'd feared might
arise...)
Discussion: https://postgr.es/m/15519-4fc785b483201ff1@postgresql.org
ftoi4 and its sibling coercion functions did their overflow checks in
a way that looked superficially plausible, but actually depended on an
assumption that the MIN and MAX comparison constants can be represented
exactly in the float4 or float8 domain. That fails in ftoi4, ftoi8,
and dtoi8, resulting in a possibility that values near the MAX limit will
be wrongly converted (to negative values) when they need to be rejected.
Also, because we compared before rounding off the fractional part,
the other three functions threw errors for values that really ought
to get rounded to the min or max integer value.
Fix by doing rint() first (requiring an assumption that it handles
NaN and Inf correctly; but dtoi8 and ftoi8 were assuming that already),
and by comparing to values that should coerce to float exactly, namely
INTxx_MIN and -INTxx_MIN. Also remove some random cosmetic discrepancies
between these six functions.
Per bug #15519 from Victor Petrovykh. This should get back-patched,
but first let's see what the buildfarm thinks of it --- I'm not too
sure about portability of some of the regression test cases.
Patch by me; thanks to Andrew Gierth for analysis and discussion.
Discussion: https://postgr.es/m/15519-4fc785b483201ff1@postgresql.org
Buildfarm results show that the modern POSIX rule that 1 ^ NaN = 1 is not
honored on *BSD until relatively recently, and really old platforms don't
believe that NaN ^ 0 = 1 either. (This is unsurprising, perhaps, since
SUSv2 doesn't require either behavior.) In hopes of getting to platform
independent behavior, let's deal with all the NaN-input cases explicitly
in dpow().
Note that numeric_power() doesn't know either of these special cases.
But since that behavior is platform-independent, I think it should be
addressed separately, and probably not back-patched.
Discussion: https://postgr.es/m/75DB81BEEA95B445AE6D576A0A5C9E936A73E741@BPXM05GP.gisp.nec.co.jp
Per spec, the result of power() should be NaN if either input is NaN.
It appears that on some versions of Windows, the libc function does
return NaN, but it also sets errno = EDOM, confusing our code that
attempts to work around shortcomings of other platforms. Hence, add
guard tests to avoid substituting a wrong result for the right one.
It's been like this for a long time (and the odd behavior only appears
in older MSVC releases, too) so back-patch to all supported branches.
Dang Minh Huong, reviewed by David Rowley
Discussion: https://postgr.es/m/75DB81BEEA95B445AE6D576A0A5C9E936A73E741@BPXM05GP.gisp.nec.co.jp
Print the actual value of each function result that's expected to be exact,
rather than merely emitting a NULL if it's not right. Although we print
these with extra_float_digits = 3, we should not trust that the platform
will produce a result visibly different from the expected value if it's off
only in the last place; hence, also include comparisons against the exact
values as before. This is a bit bulkier and uglier than the previous
printout, but it will provide more information and be easier to interpret
if there's a test failure.
Discussion: <18241.1461073100@sss.pgh.pa.us>
The implementations go to some lengths to deliver exact results for values
where an exact result can be expected, such as sind(30) = 0.5 exactly.
Dean Rasheed, reviewed by Michael Paquier
This reverts commit 500cf66d55. As was
more or less expected, a small minority of platforms won't accept
denormalized input even with the recent changes. It doesn't seem
especially helpful to test this if we're going to have to provide an
alternate expected-file to allow failure.
This was submitted with the previous patch, but I'm committing it
separately to ease backing it out if these results prove too unportable.
Marti Raudsepp, after a proposal by Jeroen Vermeulen
the fact that NetBSD/mips is currently broken, as per buildfarm member pika.
Also add regression tests to ensure that get_float8_nan and get_float4_nan
are exercised even on platforms where they are not needed by
float8in/float4in.
Zoltán Böszörményi and Tom Lane
as well as the existing pg_catalog entries for prefix and postfix %.
These have never been documented, though they did appear in one old
regression test. This avoids surprising behavior in cases like
"SELECT -25 % -10". Per recent discussion.
Note: although there is a catalog change here, I did not force initdb
since there's no harm in leaving the inaccessible entries in one's
copy of pg_operator.
in UPDATE. We also now issue a NOTICE if a query has _any_ implicit
range table entries -- in the past, we would only warn about implicit
RTEs in SELECTs with at least one explicit RTE.
As a result of the warning change, 25 of the regression tests had to
be updated. I also took the opportunity to remove some bogus whitespace
differences between some of the float4 and float8 variants. I believe
I have correctly updated all the platform-specific variants, but let
me know if that's not the case.
Original patch for DELETE ... USING from Euler Taveira de Oliveira,
reworked by Neil Conway.
Regression tests and documentation have both been updated.
SQL2003 requires that both ceiling() and ceil() be present, so I have
documented both spellings. SQL2003 doesn't mention pow() as far as I
can see, so I decided to replace pow() with power() in the documentation:
there is little reason to encourage the continued usage of a function
that isn't compliant with the standard, given a standard-compliant
alternative.
RELEASE NOTES: should state that pow() is considered deprecated
(although I don't see the need to ever remove it.)
types. Update the regression tests and the documentation to reflect
this. Remove the UNSAFE_FLOATS #ifdef.
This is only half the story: we still unconditionally reject
floating point operations that result in +/- infinity. See
recent thread on -hackers for more information.
any amount of leading or trailing whitespace (where "whitespace"
is defined by isspace()). This is for SQL conformance, as well
as consistency with other numeric types (e.g. oid, numeric).
Also refactor pg_atoi() to avoid looking at errno where not
necessary, and add a bunch of regression tests for the input
to these types.
specifically ceil(), floor(), and sign(). There may be other functions
that need to be added, but this is a start. I've included some simple
regression tests.
Neil Conway
Implement TIME WITH TIME ZONE type (timetz internal type).
Remap length() for character strings to CHAR_LENGTH() for SQL92
and to remove the ambiguity with geometric length() functions.
Keep length() for character strings for backward compatibility.
Shrink stored views by removing internal column name list from visible rte.
Implement min(), max() for time and timetz data types.
Implement conversion of TIME to INTERVAL.
Implement abs(), mod(), fac() for the int8 data type.
Rename some math functions to generic names:
round(), sqrt(), cbrt(), pow(), etc.
Rename NUMERIC power() function to pow().
Fix int2 factorial to calculate result in int4.
Enhance the Oracle compatibility function translate() to work with string
arguments (from Edwin Ramirez).
Modify pg_proc system table to remove OID holes.
test passes. Interestingly, the fix involves no changes or special
cases in the union test and actually removes a special case for the
numerology test. Thus, following the strategy outlined below is a
definite improvement over the previous situation.
Cheers,
Brook
Tom Lane
Andrew Gierth
Peter Eisentraut
Bruce Momjian
Neil Conway
Thomas G. Lockhart
Marc G. Fournier