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Regression Tests Regression Tests
The regression tests are a comprehensive set of tests for the SQL The regression tests are a comprehensive set of tests for the SQL
implementation in PostgreSQL. They test standard SQL operations as well as the implementation in PostgreSQL. They test standard SQL operations as
extended capabilities of PostgreSQL. From PostgreSQL 6.1 onward, the regression well as the extended capabilities of PostgreSQL.
tests are current for every official release. _________________________________________________________________
-------------------------------------------------------------------------------
Running the Tests Running the Tests
The regression test can be run against an already installed and running server, The regression tests can be run against an already installed and
or using a temporary installation within the build tree. Furthermore, there is running server, or using a temporary installation within the build
a "parallel" and a "sequential" mode for running the tests. The sequential tree. Furthermore, there is a "parallel" and a "sequential" mode for
method runs each test script in turn, whereas the parallel method starts up running the tests. The sequential method runs each test script in
multiple server processes to run groups of tests in parallel. Parallel testing turn, whereas the parallel method starts up multiple server processes
gives confidence that interprocess communication and locking are working to run groups of tests in parallel. Parallel testing gives confidence
correctly. For historical reasons, the sequential test is usually run against that interprocess communication and locking are working correctly. For
an existing installation and the parallel method against a temporary historical reasons, the sequential test is usually run against an
existing installation and the parallel method against a temporary
installation, but there are no technical reasons for this. installation, but there are no technical reasons for this.
To run the regression tests after building but before installation, type To run the regression tests after building but before installation,
type
gmake check gmake check
in the top-level directory. (Or you can change to "src/test/regress" and run in the top-level directory. (Or you can change to "src/test/regress"
the command there.) This will first build several auxiliary files, such as some and run the command there.) This will first build several auxiliary
sample user-defined trigger functions, and then run the test driver script. At files, such as some sample user-defined trigger functions, and then
the end you should see something like run the test driver script. At the end you should see something like
====================== ======================
All 93 tests passed. All 98 tests passed.
====================== ======================
or otherwise a note about which tests failed. See the Section called Test or otherwise a note about which tests failed. See the section called
Evaluation below for more. Test Evaluation below before assuming that a "failure" represents a
serious problem.
Because this test method runs a temporary server, it will not work when you are
the root user (since 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. For example
Because this test method runs a temporary server, it will not work
when you are the root user (since 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. For example
root# chmod -R a+w src/test/regress root# chmod -R a+w src/test/regress
root# chmod -R a+w contrib/spi root# chmod -R a+w contrib/spi
root# su - joeuser root# su - joeuser
joeuser$ cd top-level build directory joeuser$ cd top-level build directory
joeuser$ gmake check joeuser$ gmake check
(The only possible "security risk" here is that other users might be able to (The only possible "security risk" here is that other users might be
alter the regression test results behind your back. Use common sense when able to alter the regression test results behind your back. Use common
managing user permissions.) sense when managing user permissions.)
Alternatively, run the tests after installation. Alternatively, run the tests after installation.
The parallel regression test starts quite a few processes under your user ID. If you have configured PostgreSQL to install into a location where an
Presently, the maximum concurrency is twenty parallel test scripts, which means older PostgreSQL installation already exists, and you perform gmake
sixty processes: there's a server process, a psql, and usually a shell parent check before installing the new version, you may find that the tests
process for the psql for each test script. So if your system enforces a per- fail because the new programs try to use the already-installed shared
user limit on the number of processes, make sure this limit is at least libraries. (Typical symptoms are complaints about undefined symbols.)
seventy-five or so, else you may get random-seeming failures in the parallel If you wish to run the tests before overwriting the old installation,
test. If you are not in a position to raise the limit, you can cut down the you'll need to build with configure --disable-rpath. It is not
degree of parallelism by setting the MAX_CONNECTIONS parameter. For example, recommended that you use this option for the final installation,
however.
The parallel regression test starts quite a few processes under your
user ID. Presently, the maximum concurrency is twenty parallel test
scripts, which means sixty processes: there's a server process, a
psql, and usually a shell parent process for the psql for each test
script. So if your system enforces a per-user limit on the number of
processes, make sure this limit is at least seventy-five or so, else
you may get random-seeming failures in the parallel test. If you are
not in a position to raise the limit, you can cut down the degree of
parallelism by setting the MAX_CONNECTIONS parameter. For example,
gmake MAX_CONNECTIONS=10 check gmake MAX_CONNECTIONS=10 check
runs no more than ten tests concurrently. runs no more than ten tests concurrently.
On some systems, the default Bourne-compatible shell ("/bin/sh") gets confused On some systems, the default Bourne-compatible shell ("/bin/sh") gets
when it has to manage too many child processes in parallel. This may cause the confused when it has to manage too many child processes in parallel.
parallel test run to lock up or fail. In such cases, specify a different This may cause the parallel test run to lock up or fail. In such
Bourne-compatible shell on the command line, for example: cases, specify a different Bourne-compatible shell on the command
line, for example:
gmake SHELL=/bin/ksh check gmake SHELL=/bin/ksh check
If no non-broken shell is available, you may be able to work around the problem If no non-broken shell is available, you may be able to work around
by limiting the number of connections, as shown above. the problem by limiting the number of connections, as shown above.
To run the tests after installation, initialize a data area and start the
server, then type
To run the tests after installation, initialize a data area and start
the server, then type
gmake installcheck gmake installcheck
The tests will expect to contact the server at the local host and the default or for a parallel test
port number, unless directed otherwise by PGHOST and PGPORT environment gmake installcheck-parallel
variables.
------------------------------------------------------------------------------- The tests will expect to contact the server at the local host and the
default port number, unless directed otherwise by PGHOST and PGPORT
environment variables.
_________________________________________________________________
Test Evaluation Test Evaluation
Some properly installed and fully functional PostgreSQL installations can Some properly installed and fully functional PostgreSQL installations
"fail" some of these regression tests due to platform-specific artifacts such can "fail" some of these regression tests due to platform-specific
as varying floating-point representation and time zone support. The tests are artifacts such as varying floating-point representation and message
currently evaluated using a simple "diff" comparison against the outputs wording. The tests are currently evaluated using a simple "diff"
generated on a reference system, so the results are sensitive to small system comparison against the outputs generated on a reference system, so the
differences. When a test is reported as "failed", always examine the results are sensitive to small system differences. When a test is
differences between expected and actual results; you may well find that the reported as "failed", always examine the differences between expected
differences are not significant. Nonetheless, we still strive to maintain and actual results; you may well find that the differences are not
accurate reference files across all supported platforms, so it can be expected significant. Nonetheless, we still strive to maintain accurate
reference files across all supported platforms, so it can be expected
that all tests pass. that all tests pass.
The actual outputs of the regression tests are in files in the "src/test/ The actual outputs of the regression tests are in files in the
regress/results" directory. The test script uses "diff" to compare each output "src/test/regress/results" directory. The test script uses "diff" to
file against the reference outputs stored in the "src/test/regress/expected" compare each output file against the reference outputs stored in the
directory. Any differences are saved for your inspection in "src/test/regress/ "src/test/regress/expected" directory. Any differences are saved for
regression.diffs". (Or you can run "diff" yourself, if you prefer.) your inspection in "src/test/regress/regression.diffs". (Or you can
run "diff" yourself, if you prefer.)
------------------------------------------------------------------------------- If for some reason a particular platform generates a "failure" for a
given test, but inspection of the output convinces you that the result
is valid, you can add a new comparison file to silence the failure
report in future test runs. See the section called Variant Comparison
Files for details.
_________________________________________________________________
Error message differences Error message differences
Some of the regression tests involve intentional invalid input values. Error Some of the regression tests involve intentional invalid input values.
messages can come from either the PostgreSQL code or from the host platform Error messages can come from either the PostgreSQL code or from the
system routines. In the latter case, the messages may vary between platforms, host platform system routines. In the latter case, the messages may
but should reflect similar information. These differences in messages will vary between platforms, but should reflect similar information. These
result in a "failed" regression test that can be validated by inspection. differences in messages will result in a "failed" regression test that
can be validated by inspection.
------------------------------------------------------------------------------- _________________________________________________________________
Locale differences Locale differences
If you run the tests against an already-installed server that was initialized If you run the tests against an already-installed server that was
with a collation-order locale other than C, then there may be differences due initialized with a collation-order locale other than C, then there may
to sort order and follow-up failures. The regression test suite is set up to be differences due to sort order and follow-up failures. The
handle this problem by providing alternative result files that together are regression test suite is set up to handle this problem by providing
known to handle a large number of locales. For example, for the char test, the alternative result files that together are known to handle a large
expected file "char.out" handles the C and POSIX locales, and the file number of locales.
"char_1.out" handles many other locales. The regression test driver will _________________________________________________________________
automatically pick the best file to match against when checking for success and
for computing failure differences. (This means that the regression tests cannot
detect whether the results are appropriate for the configured locale. The tests
will simply pick the one result file that works best.)
If for some reason the existing expected files do not cover some locale, you
can add a new file. The naming scheme is testname_digit.out. The actual digit
is not significant. Remember that the regression test driver will consider all
such files to be equally valid test results. If the test results are platform-
specific, the technique described in the Section called Platform-specific
comparison files should be used instead.
-------------------------------------------------------------------------------
Date and time differences Date and time differences
A few of the queries in the "horology" test will fail if you run the test on Most of the date and time results are dependent on the time zone
the day of a daylight-saving time changeover, or the day after one. These environment. The reference files are generated for time zone PST8PDT
queries expect that the intervals between midnight yesterday, midnight today (Berkeley, California), and there will be apparent failures if the
and midnight tomorrow are exactly twenty-four hours --- which is wrong if tests are not run with that time zone setting. The regression test
daylight-saving time went into or out of effect meanwhile. driver sets environment variable PGTZ to PST8PDT, which normally
ensures proper results.
Note: Because USA daylight-saving time rules are used, this problem _________________________________________________________________
always occurs on the first Sunday of April, the last Sunday of
October, and their following Mondays, regardless of when daylight-
saving time is in effect where you live. Also note that the problem
appears or disappears at midnight Pacific time (UTC-7 or UTC-8), not
midnight your local time. Thus the failure may appear late on
Saturday or persist through much of Tuesday, depending on where you
live.
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, which normally ensures proper results. However, your operating system
must provide 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 time zone is not available, then your system may have
returned the time in UTC. If the PST8PDT time zone is missing, you can set the
time zone rules explicitly:
PGTZ='PST8PDT7,M04.01.0,M10.05.03'; export PGTZ
There appear to be some systems that 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-saving
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.
-------------------------------------------------------------------------------
Floating-point differences Floating-point differences
Some of the tests involve computing 64-bit floating-point numbers (double Some of the tests involve computing 64-bit floating-point numbers
precision) from table columns. Differences in results involving mathematical (double precision) from table columns. Differences in results
functions of double precision columns have been observed. The float8 and involving mathematical functions of double precision columns have been
geometry tests are particularly prone to small differences across platforms, or observed. The float8 and geometry tests are particularly prone to
even with different compiler optimization options. Human eyeball comparison is small differences across platforms, or even with different compiler
needed to determine the real significance of these differences which are optimization options. Human eyeball comparison is needed to determine
usually 10 places to the right of the decimal point. the real significance of these differences which are usually 10 places
to the right of the decimal point.
Some systems display minus zero as -0, while others just show 0. Some systems display minus zero as -0, while others just show 0.
Some systems signal errors from pow() and exp() differently from the mechanism Some systems signal errors from pow() and exp() differently from the
expected by the current PostgreSQL code. mechanism expected by the current PostgreSQL code.
_________________________________________________________________
-------------------------------------------------------------------------------
Row ordering differences Row ordering differences
You might see differences in which the same rows are output in a different You might see differences in which the same rows are output in a
order than what appears in the expected file. In most cases this is not, different order than what appears in the expected file. In most cases
strictly speaking, a bug. Most of the regression test scripts are not so this is not, strictly speaking, a bug. Most of the regression test
pedantic as to use an ORDER BY for every single SELECT, and so their result row scripts are not so pedantic as to use an ORDER BY for every single
orderings are not well-defined according to the letter of the SQL SELECT, and so their result row orderings are not well-defined
specification. In practice, since we are looking at the same queries being according to the letter of the SQL specification. In practice, since
executed on the same data by the same software, we usually get the same result we are looking at the same queries being executed on the same data by
ordering on all platforms, and so the lack of ORDER BY isn't a problem. Some the same software, we usually get the same result ordering on all
queries do exhibit cross-platform ordering differences, however. (Ordering platforms, and so the lack of ORDER BY isn't a problem. Some queries
differences can also be triggered by non-C locale settings.) do exhibit cross-platform ordering differences, however. When testing
against an already-installed server, ordering differences can also be
caused by non-C locale settings or non-default parameter settings,
such as custom values of work_mem or the planner cost parameters.
Therefore, if you see an ordering difference, it's not something to worry Therefore, if you see an ordering difference, it's not something to
about, unless the query does have an ORDER BY that your result is violating. worry about, unless the query does have an ORDER BY that your result
But please report it anyway, so that we can add an ORDER BY to that particular is violating. But please report it anyway, so that we can add an ORDER
query and thereby eliminate the bogus "failure" in future releases. BY to that particular query and thereby eliminate the bogus "failure"
in future releases.
You might wonder why we don't order all the regression test queries explicitly You might wonder why we don't order all the regression test queries
to get rid of this issue once and for all. The reason is that that would make explicitly to get rid of this issue once and for all. The reason is
the regression tests less useful, not more, since they'd tend to exercise query that that would make the regression tests less useful, not more, since
plan types that produce ordered results to the exclusion of those that don't. they'd tend to exercise query plan types that produce ordered results
to the exclusion of those that don't.
------------------------------------------------------------------------------- _________________________________________________________________
The "random" test The "random" test
There is at least one case in the random test script that is intended to The random test script is intended to produce random results. In rare
produce random results. This causes random to fail the regression test once in cases, this causes the random regression test to fail. Typing
a while (perhaps once in every five to ten trials). Typing
diff results/random.out expected/random.out diff results/random.out expected/random.out
should produce only one or a few lines of differences. You need not worry should produce only one or a few lines of differences. You need not
unless the random test always fails in repeated attempts. (On the other hand, worry unless the random test fails repeatedly.
if the random test is *never* reported to fail even in many trials of the _________________________________________________________________
regression tests, you probably *should* worry.)
------------------------------------------------------------------------------- Variant Comparison Files
Platform-specific comparison files Since some of the tests inherently produce environment-dependent
results, we have provided ways to specify alternative "expected"
result files. Each regression test can have several comparison files
showing possible results on different platforms. There are two
independent mechanisms for determining which comparison file is used
for each test.
Since some of the tests inherently produce platform-specific results, we have The first mechanism allows comparison files to be selected for
provided a way to supply platform-specific result comparison files. Frequently, specific platforms. There is a mapping file,
the same variation applies to multiple platforms; rather than supplying a "src/test/regress/resultmap", that defines which comparison file to
separate comparison file for every platform, there is a mapping file that use for each platform. To eliminate bogus test "failures" for a
defines which comparison file to use. So, to eliminate bogus test "failures" particular platform, you first choose or make a variant result file,
for a particular platform, you must choose or make a variant result file, and and then add a line to the "resultmap" file.
then add a line to the mapping file, which is "src/test/regress/resultmap".
Each line in the mapping file is of the form Each line in the mapping file is of the form
testname/platformpattern=comparisonfilename testname/platformpattern=comparisonfilename
The test name is just the name of the particular regression test module. The The test name is just the name of the particular regression test
platform pattern is a pattern in the style of the Unix tool "expr" (that is, a module. The platform pattern is a pattern in the style of the Unix
regular expression with an implicit ^ anchor at the start). It is matched tool "expr" (that is, a regular expression with an implicit ^ anchor
against the platform name as printed by "config.guess" followed by :gcc or :cc, at the start). It is matched against the platform name as printed by
depending on whether you use the GNU compiler or the system's native compiler "config.guess" followed by :gcc or :cc, depending on whether you use
(on systems where there is a difference). The comparison file name is the name the GNU compiler or the system's native compiler (on systems where
of the substitute result comparison file. there is a difference). The comparison file name is the base name of
the substitute result comparison file.
For example: some systems using older time zone libraries fail to apply For example: some systems interpret very small floating-point values
daylight-saving corrections to dates before 1970, causing pre-1970 PDT times to as zero, rather than reporting an underflow error. This causes a few
be displayed in PST instead. This causes a few differences in the "horology" differences in the "float8" regression test. Therefore, we provide a
regression test. Therefore, we provide a variant comparison file, "horology-no- variant comparison file, "float8-small-is-zero.out", which includes
DST-before-1970.out", which includes the results to be expected on these the results to be expected on these systems. To silence the bogus
systems. To silence the bogus "failure" message on HPUX platforms, "resultmap" "failure" message on OpenBSD platforms, "resultmap" includes
includes float8/i.86-.*-openbsd=float8-small-is-zero
horology/.*-hpux=horology-no-DST-before-1970 which will trigger on any machine for which the output of
"config.guess" matches i.86-.*-openbsd. Other lines in "resultmap"
select the variant comparison file for other platforms where it's
appropriate.
which will trigger on any machine for which the output of "config.guess" The second selection mechanism for variant comparison files is much
includes -hpux. Other lines in "resultmap" select the variant comparison file more automatic: it simply uses the "best match" among several supplied
for other platforms where it's appropriate. comparison files. The regression test driver script considers both the
standard comparison file for a test, testname.out, and variant files
named testname_digit.out (where the "digit" is any single digit 0-9).
If any such file is an exact match, the test is considered to pass;
otherwise, the one that generates the shortest diff is used to create
the failure report. (If "resultmap" includes an entry for the
particular test, then the base "testname" is the substitute name given
in "resultmap".)
For example, for the char test, the comparison file "char.out"
contains results that are expected in the C and POSIX locales, while
the file "char_1.out" contains results sorted as they appear in many
other locales.
The best-match mechanism was devised to cope with locale-dependent
results, but it can be used in any situation where the test results
cannot be predicted easily from the platform name alone. A limitation
of this mechanism is that the test driver cannot tell which variant is
actually "correct" for the current environment; it will just pick the
variant that seems to work best. Therefore it is safest to use this
mechanism only for variant results that you are willing to consider
equally valid in all contexts.