REGRESSION TESTS

The regression tests are a comprehensive set of tests for the SQL
implementation in PostgreSQL. They test standard SQL operations as
well as the extended capabilities of PostgreSQL. The test suite was
originally developed by Jolly Chen and Andrew Yu, and was extensively
revised and repackaged by Marc Fournier and Thomas Lockhart. From
PostgreSQL 6.1 onward the regression tests are current for every
official release.

The regression test can be run against an already installed and
running server, or using a temporary installation within the build
tree.  Furthermore, there is a "parallel" and a "sequential" mode for
running the tests. The sequential method runs each test script in
turn, whereas the parallel method starts up multiple server processes
to run groups of tests in parallel. Parallel testing gives confidence
that interprocess communication and locking are working correctly. For
historical reasons, the sequential test is usually run against an
existing installation and the parallel method "stand-alone", but there
are technical reasons for this.

To run the regression tests after building but before installation,
type

$ gmake check

in the top-level directory. (Or you can change to src/test/regress and
run the command there.) This will first build several auxiliary files,
such as platform-dependent "expected" files and some sample
user-defined trigger functions, and then run the test driver
script. At the end you should see something like

======================
 All 75 tests passed.
======================

or otherwise a note about what tests failed. See the section called
Test Evaluation below for more.

     Note: Because this test method runs a temporary server, it will
     not work when you are the root user (the server will not start as
     root). If you already did the build as root, you do not have to
     start all over. Instead, make the regression test directory
     writable by some other user, log in as that user, and restart the
     tests.

     root# chmod -R a+w src/test/regress
     root# su - joeuser
     joeuser$ gmake check

     (The only possible "security risk" here is that other users might
     be able to alter the regression test results behind your back. Use
     common sense when managing user permissions.)

     Alternatively, run the tests after installation.

     Tip: On some systems, the default Bourne-compatible shell
     (/bin/sh) gets confused when it has to manage too many child
     processes in parallel. This may cause the parallel test run to
     lock up or fail. In such cases, specify a different
     Bourne-compatible shell on the command line, for example:

     $ gmake SHELL=/bin/ksh check

To run the tests after installation, initialize a data area and start
the server, then type

$ gmake installcheck

The server is expected to be running on the local host with the
default port number.

Test Evaluation

Some properly installed and fully functional PostgreSQL installations
can "fail" some of these regression tests due to artifacts of floating
point representation and time zone support. The tests are currently
evaluated using a simple diff comparison against the outputs generated
on a reference system, so the results are sensitive to small system
differences. When a test is reported as "failed", always examine the
differences between expected and actual results; you may well find
that the differences are not significant. Nonetheless, we still strive
to maintain accurate reference files across all supported platforms,
so it can be expected that all tests pass.

The actual outputs of the regression tests are in files in the
src/test/regress/results directory. The test script uses diff to
compare each output file against the reference outputs stored in the
src/test/regress/expected directory. Any differences are saved for
your inspection in src/test/regress/regression.diffs. (Or you can run
diff yourself, if you prefer.)

Error message differences

Some of the regression tests involve intentional invalid input
values. Error messages can come from either the PostgreSQL code or
from the host platform system routines. In the latter case, the
messages may vary between platforms, but should reflect similar
information. These differences in messages will result in a "failed"
regression test which can be validated by inspection.

Date and time differences

Most of the date and time results are dependent on the time zone
environment. The reference files are generated for time zone PST8PDT
(Berkeley, California) and there will be apparent failures if the
tests are not run with that time zone setting. The regression test
driver sets environment variable PGTZ to PST8PDT to ensure proper
results. However, your system must provide library support for the
PST8PDT time zone, or the time zone-dependent tests will fail. To
verify that your machine does have this support, type the following:

$ env TZ=PST8PDT date

The command above should have returned the current system time in the
PST8PDT time zone. If the PST8PDT database is not available, then your
system may have returned the time in GMT. If the PST8PDT time zone is
not available, you can set the time zone rules explicitly:

PGTZ='PST8PDT7,M04.01.0,M10.05.03'; export PGTZ

There appear to be some systems which do not accept the recommended
syntax for explicitly setting the local time zone rules; you may need
to use a different PGTZ setting on such machines.

Some systems using older time zone libraries fail to apply
daylight-savings corrections to dates before 1970, causing pre-1970
PDT times to be displayed in PST instead. This will result in
localized differences in the test results.

Some of the queries in the "timestamp" test will fail if you run the
test on the day of a daylight-savings time changeover, or the day
before or after one. These queries assume that the intervals between
midnight yesterday, midnight today and midnight tomorrow are exactly
twenty-four hours -- which is wrong if daylight-savings time went into
or out of effect meanwhile.

Floating point differences

Some of the tests involve computing 64-bit (double precision) numbers
from table columns. Differences in results involving mathematical
functions of double precision columns have been observed. The float8
and geometry tests are particularly prone to small differences across
platforms, or even with different compiler optimization options. Human
eyeball comparison is needed to determine the real significance of
these differences which are usually 10 places to the right of the
decimal point.

Some systems signal errors from pow() and exp() differently from the
mechanism expected by the current PostgreSQL code.

Polygon differences

Several of the tests involve operations on geographic data about the
Oakland/Berkeley, CA street map. The map data is expressed as polygons
whose vertices are represented as pairs of double precision numbers
(decimal latitude and longitude). Initially, some tables are created
and loaded with geographic data, then some views are created which
join two tables using the polygon intersection operator (##), then a
select is done on the view.

When comparing the results from different platforms, differences occur
in the 2nd or 3rd place to the right of the decimal point. The SQL
statements where these problems occur are the following:

SELECT * from street;
SELECT * from iexit;

The "random" test

There is at least one case in the "random" test script that is
intended to produce random results. This causes random to fail the
regression test once in a while (perhaps once in every five to ten
trials). Typing

diff results/random.out expected/random.out

should produce only one or a few lines of differences. You need not
worry unless the random test always fails in repeated attempts. (On
the other hand, if the random test is never reported to fail even in
many trials of the regress tests, you probably should worry.)

Platform-specific comparison files

Since some of the tests inherently produce platform-specific results,
we have provided a way to supply platform-specific result comparison
files.  Frequently, the same variation applies to multiple platforms;
rather than supplying a separate comparison file for every platform,
there is a mapping file that defines which comparison file to use. So,
to eliminate bogus test "failures" for a particular platform, you must
choose or make a variant result file, and then add a line to the
mapping file, which is "resultmap".

Each line in the mapping file is of the form

    testname/platformpattern=comparisonfilename

The test name is just the name of the particular regression test
module. The platform pattern is a pattern in the style of expr(1)
(that is, a regular expression with an implicit ^ anchor at the start).
It is matched against the platform name as printed by config.guess
followed by ":gcc" or ":cc", depending on whether you use the GNU compiler
or the system's native compiler (on systems where there is a difference).
The comparison file name is the name of the substitute result comparison
file.

For example: the int2 regress test includes a deliberate entry of a
value that is too large to fit in int2. The specific error message
that is produced is platform-dependent; our reference platform emits

    ERROR:  pg_atoi: error reading "100000": Numerical result out of range

but a fair number of other Unix platforms emit

    ERROR:  pg_atoi: error reading "100000": Result too large

Therefore, we provide a variant comparison file, int2-too-large.out,
that includes this spelling of the error message. To silence the bogus
"failure" message on HPPA platforms, resultmap includes

                int2/hppa=int2-too-large

which will trigger on any machine for which config.guess's output
begins with 'hppa'. Other lines in resultmap select the variant
comparison file for other platforms where it's appropriate.
