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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.
__________________________________________________________________
Running the Tests
The regression tests 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 alone,
while 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.
__________________________________________________________________
Running the Tests Against a Temporary Installation
To run the parallel 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 sample user-defined trigger functions, and then run the
test driver script. At the end you should see something like:
=======================
All 115 tests passed.
=======================
or otherwise a note about which tests failed. See the Section called
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:
root# chmod -R a+w src/test/regress
root# su - joeuser
joeuser$ cd top-level build directory
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.
If you have configured PostgreSQL to install into a location where an
older PostgreSQL installation already exists, and you perform gmake
check before installing the new version, you might find that the tests
fail because the new programs try to use the already-installed shared
libraries. (Typical symptoms are complaints about undefined symbols.)
If you wish to run the tests before overwriting the old installation,
you'll need to build with configure --disable-rpath. It is not
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 forty processes: there's a server process and a
psql process 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 fifty or so, else you might 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
runs no more than ten tests concurrently.
__________________________________________________________________
Running the Tests Against an Existing Installation
To run the tests after installation, initialize a data area and start
the server, then type:
gmake installcheck
or for a parallel test:
gmake installcheck-parallel
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.
The source distribution also contains regression tests for the optional
procedural languages and for some of the "contrib" modules. At present,
these tests can be used only against an already-installed server. To
run the tests for all procedural languages that have been built and
installed, change to the "src/pl" directory of the build tree and type:
gmake installcheck
You can also do this in any of the subdirectories of "src/pl" to run
tests for just one procedural language. To run the tests for all
"contrib" modules that have them, change to the "contrib" directory of
the build tree and type:
gmake installcheck
The "contrib" modules must have been built and installed first. You can
also do this in a subdirectory of "contrib" to run the tests for just
one module.
__________________________________________________________________
Testing Hot Standby
The source distribution also contains regression tests of the static
behavior of Hot Standby. These tests require a running primary server
and a running standby server that is accepting new WAL changes from the
primary using either file-based log shipping or streaming replication.
Those servers are not automatically created for you, nor is the setup
documented here. Please check the various sections of the documentation
already devoted to the required commands and related issues.
First create a database called "regression" on the primary.
psql -h primary -c "CREATE DATABASE regression"
Next, run a preparatory script on the primary in the regression
database: "src/test/regress/sql/hs_primary_setup.sql", and allow for
the changes to propagate to the standby, for example
psql -h primary -f src/test/regress/sql/hs_primary_setup.sql regression
Now confirm that the default connection for the tester is the standby
server under test and then run the standbycheck target from the
regression directory:
cd src/test/regress
gmake standbycheck
Some extreme behaviors can also be generated on the primary using the
script: "src/test/regress/sql/hs_primary_extremes.sql" to allow the
behavior of the standby to be tested.
Additional automated testing may be available in later releases.
__________________________________________________________________
Locale and Encoding
By default, the tests against a temporary installation use the locale
defined in the current environment and the corresponding database
encoding as determined by "initdb". It can be useful to test different
locales by setting the appropriate environment variables, for example:
gmake check LANG=C
gmake check LC_COLLATE=en_US.utf8 LC_CTYPE=fr_CA.utf8
For implementation reasons, setting LC_ALL does not work for this
purpose; all the other locale-related environment variables do work.
When testing against an existing installation, the locale is determined
by the existing database cluster and cannot be set separately for the
test run.
You can also choose the database encoding explicitly by setting the
variable ENCODING, for example:
gmake check LANG=C ENCODING=EUC_JP
Setting the database encoding this way typically only makes sense if
the locale is C; otherwise the encoding is chosen automatically from
the locale, and specifying an encoding that does not match the locale
will result in an error.
The encoding can be set for tests against a temporary or an existing
installation.
__________________________________________________________________
Extra Tests
The regression test suite contains a few test files that are not run by
default, because they might be platform-dependent or take a very long
time to run. You can run these or other extra test files by setting the
variable EXTRA_TESTS. For example, to run the numeric_big test:
gmake check EXTRA_TESTS=numeric_big
To run the collation tests:
gmake check EXTRA_TESTS=collate.linux.utf8 LANG=en_US.utf8
The collate.linux.utf8 test works only on Linux/glibc platforms, and
only when run in a database that uses UTF-8 encoding.
__________________________________________________________________
Test Evaluation
Some properly installed and fully functional PostgreSQL installations
can "fail" some of these regression tests due to platform-specific
artifacts such as varying floating-point representation and message
wording. 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 might 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". If you don't
like the "diff" options that are used by default, set the environment
variable PG_REGRESS_DIFF_OPTS, for instance PG_REGRESS_DIFF_OPTS='-u'.
(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
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 can
vary between platforms, but should reflect similar information. These
differences in messages will result in a "failed" regression test that
can be validated by inspection.
__________________________________________________________________
Locale Differences
If you run the tests against a server that was initialized with a
collation-order locale other than C, then there might be differences
due to sort order and subsequent failures. The regression test suite is
set up to handle this problem by providing alternate result files that
together are known to handle a large number of locales.
To run the tests in a different locale when using the
temporary-installation method, pass the appropriate locale-related
environment variables on the "make" command line, for example:
gmake check LANG=de_DE.utf8
(The regression test driver unsets LC_ALL, so it does not work to
choose the locale using that variable.) To use no locale, either unset
all locale-related environment variables (or set them to C) or use the
following special invocation:
gmake check NO_LOCALE=1
When running the tests against an existing installation, the locale
setup is determined by the existing installation. To change it,
initialize the database cluster with a different locale by passing the
appropriate options to "initdb".
In general, it is nevertheless advisable to try to run the regression
tests in the locale setup that is wanted for production use, as this
will exercise the locale- and encoding-related code portions that will
actually be used in production. Depending on the operating system
environment, you might get failures, but then you will at least know
what locale-specific behaviors to expect when running real
applications.
__________________________________________________________________
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, which normally
ensures proper results.
__________________________________________________________________
Floating-Point Differences
Some of the tests involve computing 64-bit floating-point numbers
(double precision) 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 setting. 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 display minus zero as -0, while others just show 0.
Some systems signal errors from pow() and exp() differently from the
mechanism expected by the current PostgreSQL code.
__________________________________________________________________
Row Ordering Differences
You might see differences in which the same rows are output in a
different order than what appears in the expected file. In most cases
this is not, strictly speaking, a bug. Most of the regression test
scripts are not so pedantic as to use an ORDER BY for every single
SELECT, and so their result row orderings are not well-defined
according to the SQL specification. In practice, since we are looking
at the same queries being executed on the same data by the same
software, we usually get the same result ordering on all platforms, so
the lack of ORDER BY is not a problem. Some queries 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 about, unless the query does have an ORDER BY that your result is
violating. However, please report it anyway, so that we can add an
ORDER BY to that particular query to eliminate the bogus "failure" in
future releases.
You might wonder why we don't order all the regression test queries
explicitly to get rid of this issue once and for all. The reason is
that that would make the regression tests less useful, not more, since
they'd tend to exercise query plan types that produce ordered results
to the exclusion of those that don't.
__________________________________________________________________
Insufficient Stack Depth
If the errors test results in a server crash at the select
infinite_recurse() command, it means that the platform's limit on
process stack size is smaller than the max_stack_depth parameter
indicates. This can be fixed by running the server under a higher stack
size limit (4MB is recommended with the default value of
max_stack_depth). If you are unable to do that, an alternative is to
reduce the value of max_stack_depth.
__________________________________________________________________
The "random" Test
The random test script is intended to produce random results. In rare
cases, this causes the random regression test to fail. 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 fails repeatedly.
__________________________________________________________________
Variant Comparison Files
Since some of the tests inherently produce environment-dependent
results, we have provided ways to specify alternate "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.
The first mechanism allows comparison files to be selected for specific
platforms. There is a mapping file, "src/test/regress/resultmap", that
defines which comparison file to use for each platform. To eliminate
bogus test "failures" for a particular platform, you first choose or
make a variant result file, and then add a line to the "resultmap"
file.
Each line in the mapping file is of the form
testname:output:platformpattern=comparisonfilename
The test name is just the name of the particular regression test
module. The output value indicates which output file to check. For the
standard regression tests, this is always out. The value corresponds to
the file extension of the output file. The platform pattern is a
pattern in the style of the Unix tool "expr" (that is, a regular
expression with an implicit ^ anchor at the start). It is matched
against the platform name as printed by "config.guess". The comparison
file name is the base name of the substitute result comparison file.
For example: some systems interpret very small floating-point values as
zero, rather than reporting an underflow error. This causes a few
differences in the "float8" regression test. Therefore, we provide a
variant comparison file, "float8-small-is-zero.out", which includes the
results to be expected on these systems. To silence the bogus "failure"
message on OpenBSD platforms, "resultmap" includes:
float8:out:i.86-.*-openbsd=float8-small-is-zero.out
which will trigger on any machine where 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.
The second selection mechanism for variant comparison files is much
more automatic: it simply uses the "best match" among several supplied
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.
__________________________________________________________________
Test Coverage Examination
The PostgreSQL source code can be compiled with coverage testing
instrumentation, so that it becomes possible to examine which parts of
the code are covered by the regression tests or any other test suite
that is run with the code. This is currently supported when compiling
with GCC and requires the "gcov" and "lcov" programs.
A typical workflow would look like this:
./configure --enable-coverage ... OTHER OPTIONS ...
gmake
gmake check # or other test suite
gmake coverage-html
Then point your HTML browser to "coverage/index.html". The "gmake"
commands also work in subdirectories.
To reset the execution counts between test runs, run:
gmake coverage-clean
|