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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. From PostgreSQL 6.1 onward, the regression tests are current for every official release. ------------------------------------------------------------------------------- Running the Tests 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 against a temporary installation, but there are no 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 some sample user-defined trigger functions, and then run the test driver script. At the end you should see something like ====================== All 93 tests passed. ====================== or otherwise a note about which tests failed. See the Section called Test Evaluation below for more. 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 contrib/spi 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. 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 runs no more than ten tests concurrently. 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 If no non-broken shell is available, you may be able to work around 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 gmake installcheck 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 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 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 that can be validated by inspection. ------------------------------------------------------------------------------- Locale differences If you run the tests against an already-installed server that was initialized with a collation-order locale other than C, then there may be differences due to sort order and follow-up failures. The regression test suite is set up to handle this problem by providing alternative result files that together are known to handle a large number of locales. For example, for the char test, the expected file "char.out" handles the C and POSIX locales, and the file "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 A few of the queries in the "horology" test will fail if you run the test on the day of a daylight-saving time changeover, or the day after one. These queries expect that the intervals between midnight yesterday, midnight today and midnight tomorrow are exactly twenty-four hours --- which is wrong if daylight-saving time went into or out of effect meanwhile. 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 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 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 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 letter of 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, and so the lack of ORDER BY isn't a problem. Some queries do exhibit cross-platform ordering differences, however. (Ordering differences can also be triggered by non-C locale settings.) 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. But please report it anyway, so that we can add an ORDER 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 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. ------------------------------------------------------------------------------- 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 regression 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 "src/test/regress/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 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" 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: 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 causes a few differences in the "horology" regression test. Therefore, we provide a variant comparison file, "horology-no- DST-before-1970.out", which includes the results to be expected on these systems. To silence the bogus "failure" message on HPUX platforms, "resultmap" includes horology/.*-hpux=horology-no-DST-before-1970 which will trigger on any machine for which the output of "config.guess" includes -hpux. Other lines in "resultmap" select the variant comparison file for other platforms where it's appropriate.