Many older tests where written in a style like
SELECT '' AS two, i.* FROM INT2_TBL
where the first column indicated the number of expected result rows.
This has gotten increasingly out of date, as the test data fixtures
have expanded, so a lot of these were wrong and misleading. Moreover,
this style isn't really necessary, since the psql output already shows
the number of result rows.
To clean this up, remove all those extra columns.
Discussion: https://www.postgresql.org/message-id/flat/1a25312b-2686-380d-3c67-7a69094a999f%40enterprisedb.com
Our documentation describes four allowed input syntaxes for circles,
but the regression tests tried only three ... with predictable
consequences. Remarkably, this has been wrong since the circle
datatype was added in 1997, but nobody noticed till now.
David Zhang, with some help from me
Discussion: https://postgr.es/m/332c47fa-d951-7574-b5cc-a8f7f7201202@highgo.ca
We were setting extra_float_digits = 0 to avoid platform-dependent
output in this test, but that's still able to expose platform-specific
roundoff behavior in some new test cases added by commit a3d284485,
as reported by Peter Eisentraut. Reduce it to -1 to hide that.
(Over in geometry.sql, we're using -3, which is an ancient decision
dating to 337f73b1b. I wonder whether that's overkill now. But
there's probably little value in trying to change it.)
Back-patch to v12 where a3d284485 came in; there's no evidence that
we have any platform-dependent issues here before that.
Discussion: https://postgr.es/m/15551268-e224-aa46-084a-124b64095ee3@2ndquadrant.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
This commit significantly increases test coverage of geo_ops.c, adding
tests for various issues addressed by 2e2a392de3 (which went undetected
for a long time, at least partially due to not being covered).
This also removes alternative results expecting -0 on some platforms.
Instead the functions are should return the same results everywhere,
transforming -0 to 0 if needed.
The tests are added to geometric.sql file, sorted by the left hand side
of the operators. There are many cross datatype operators, so this seems
like the best solution.
Author: Emre Hasegeli
Reviewed-by: Tomas Vondra
Discussion: https://www.postgresql.org/message-id/CAE2gYzxF7-5djV6-cEvqQu-fNsnt%3DEqbOURx7ZDg%2BVv6ZMTWbg%40mail.gmail.com
per-column options for btree indexes. The planner's support for this is still
pretty rudimentary; it does not yet know how to plan mergejoins with
nondefault ordering options. The documentation is pretty rudimentary, too.
I'll work on improving that stuff later.
Note incompatible change from prior behavior: ORDER BY ... USING will now be
rejected if the operator is not a less-than or greater-than member of some
btree opclass. This prevents less-than-sane behavior if an operator that
doesn't actually define a proper sort ordering is selected.
datatype by array_eq and array_cmp; use this to solve problems with memory
leaks in array indexing support. The parser's equality_oper and ordering_oper
routines also use the cache. Change the operator search algorithms to look
for appropriate btree or hash index opclasses, instead of assuming operators
named '<' or '=' have the right semantics. (ORDER BY ASC/DESC now also look
at opclasses, instead of assuming '<' and '>' are the right things.) Add
several more index opclasses so that there is no regression in functionality
for base datatypes. initdb forced due to catalog additions.
variation. To do this, set extra_float_digits to -3 in the geometry
test, and tweak the CIRCLE_TBL dataset to avoid values that suffer
from severe cancellation error (eg, circles that just touch an axis).
We still need two geometry 'expected' files to account for the
difference between platforms that display minus zero as '-0' and those
that just say '0', but with luck that's all we'll need.
Peter Eisentraut
Tom Lane
Andrew Gierth
Tomas Vondra
Peter Eisentraut
Thomas G. Lockhart
Bruce Momjian