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"make all", and then reference them there during the actual tests. This makes the handling of these files more parallel to that of regress.so, and in particular simplifies use of the regression tests outside the original build tree. The PGDG and Red Hat RPMs have been doing this via patches for a very long time. Inclusion of the change in core was requested by Jørgen Austvik of Sun, and I can't see any reason not to. I attempted to fix the MSVC scripts for this too, but they may need further tweaking ...
424 lines
18 KiB
Plaintext
424 lines
18 KiB
Plaintext
<!-- $PostgreSQL: pgsql/doc/src/sgml/regress.sgml,v 1.59 2008/05/30 00:04:32 tgl Exp $ -->
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<chapter id="regress">
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<title id="regress-title">Regression Tests</title>
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<indexterm zone="regress">
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<primary>regression tests</primary>
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</indexterm>
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<indexterm zone="regress">
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<primary>test</primary>
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</indexterm>
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<para>
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The regression tests are a comprehensive set of tests for the SQL
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implementation in <productname>PostgreSQL</productname>. They test
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standard SQL operations as well as the extended capabilities of
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<productname>PostgreSQL</productname>.
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</para>
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<sect1 id="regress-run">
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<title>Running the Tests</title>
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<para>
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The regression tests can be run against an already installed and
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running server, or using a temporary installation within the build
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tree. Furthermore, there is a <quote>parallel</quote> and a
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<quote>sequential</quote> mode for running the tests. The
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sequential method runs each test script in turn, whereas the
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parallel method starts up multiple server processes to run groups
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of tests in parallel. Parallel testing gives confidence that
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interprocess communication and locking are working correctly. For
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historical reasons, the sequential test is usually run against an
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existing installation and the parallel method against a temporary
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installation, but there are no technical reasons for this.
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</para>
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<para>
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To run the regression tests after building but before installation,
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type
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<screen>
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gmake check
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</screen>
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in the top-level directory. (Or you can change to
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<filename>src/test/regress</filename> and run the command there.)
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This will first build several auxiliary files, such as
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some sample user-defined trigger functions, and then run the test driver
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script. At the end you should see something like
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<screen>
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<computeroutput>
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=======================
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All 115 tests passed.
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=======================
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</computeroutput>
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</screen>
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or otherwise a note about which tests failed. See <xref
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linkend="regress-evaluation"> below before assuming that a
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<quote>failure</> represents a serious problem.
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</para>
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<para>
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Because this test method runs a temporary server, it will not work
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when you are the root user (since the server will not start as root).
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If you already did the build as root, you do not have to start all
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over. Instead, make the regression test directory writable by
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some other user, log in as that user, and restart the tests.
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For example
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<screen>
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<prompt>root# </prompt><userinput>chmod -R a+w src/test/regress</userinput>
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<prompt>root# </prompt><userinput>su - joeuser</userinput>
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<prompt>joeuser$ </prompt><userinput>cd <replaceable>top-level build directory</></userinput>
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<prompt>joeuser$ </prompt><userinput>gmake check</userinput>
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</screen>
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(The only possible <quote>security risk</quote> here is that other
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users might be able to alter the regression test results behind
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your back. Use common sense when managing user permissions.)
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</para>
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<para>
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Alternatively, run the tests after installation.
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</para>
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<para>
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If you have configured <productname>PostgreSQL</productname> to install
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into a location where an older <productname>PostgreSQL</productname>
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installation already exists, and you perform <literal>gmake check</>
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before installing the new version, you might find that the tests fail
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because the new programs try to use the already-installed shared
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libraries. (Typical symptoms are complaints about undefined symbols.)
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If you wish to run the tests before overwriting the old installation,
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you'll need to build with <literal>configure --disable-rpath</>.
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It is not recommended that you use this option for the final installation,
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however.
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</para>
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<para>
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The parallel regression test starts quite a few processes under your
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user ID. Presently, the maximum concurrency is twenty parallel test
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scripts, which means forty processes: there's a server process and a
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<application>psql</> process for each test script.
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So if your system enforces a per-user limit on the number of processes,
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make sure this limit is at least fifty or so, else you might get
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random-seeming failures in the parallel test. If you are not in
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a position to raise the limit, you can cut down the degree of parallelism
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by setting the <literal>MAX_CONNECTIONS</> parameter. For example,
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<screen>
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gmake MAX_CONNECTIONS=10 check
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</screen>
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runs no more than ten tests concurrently.
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</para>
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<para>
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To run the tests after installation<![%standalone-ignore;[ (see <xref linkend="installation">)]]>,
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initialize a data area and start the
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server, <![%standalone-ignore;[as explained in <xref linkend="runtime">, ]]> then type
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<screen>
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gmake installcheck
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</screen>
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or for a parallel test
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<screen>
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gmake installcheck-parallel
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</screen>
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The tests will expect to contact the server at the local host and the
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default port number, unless directed otherwise by <envar>PGHOST</envar> and
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<envar>PGPORT</envar> environment variables.
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</para>
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<para>
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The source distribution also contains regression tests for the optional
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procedural languages and for some of the <filename>contrib</> modules.
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At present, these tests can be used only against an already-installed
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server. To run the tests for all procedural languages that have been
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built and installed, change to the <filename>src/pl</> directory of the
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build tree and type
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<screen>
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gmake installcheck
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</screen>
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You can also do this in any of the subdirectories of <filename>src/pl</>
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to run tests for just one procedural language. To run the tests for all
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<filename>contrib</> modules that have them, change to the
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<filename>contrib</> directory of the build tree and type
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<screen>
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gmake installcheck
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</screen>
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The <filename>contrib</> modules must have been built and installed first.
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You can also do this in a subdirectory of <filename>contrib</> to run
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the tests for just one module.
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</para>
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</sect1>
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<sect1 id="regress-evaluation">
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<title>Test Evaluation</title>
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<para>
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Some properly installed and fully functional
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<productname>PostgreSQL</productname> installations can
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<quote>fail</quote> some of these regression tests due to
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platform-specific artifacts such as varying floating-point representation
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and message wording. The tests are currently evaluated using a simple
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<command>diff</command> comparison against the outputs
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generated on a reference system, so the results are sensitive to
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small system differences. When a test is reported as
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<quote>failed</quote>, always examine the differences between
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expected and actual results; you might find that the
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differences are not significant. Nonetheless, we still strive to
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maintain accurate reference files across all supported platforms,
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so it can be expected that all tests pass.
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</para>
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<para>
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The actual outputs of the regression tests are in files in the
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<filename>src/test/regress/results</filename> directory. The test
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script uses <command>diff</command> to compare each output
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file against the reference outputs stored in the
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<filename>src/test/regress/expected</filename> directory. Any
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differences are saved for your inspection in
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<filename>src/test/regress/regression.diffs</filename>. (Or you
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can run <command>diff</command> yourself, if you prefer.)
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</para>
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<para>
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If for some reason a particular platform generates a <quote>failure</>
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for a given test, but inspection of the output convinces you that
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the result is valid, you can add a new comparison file to silence
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the failure report in future test runs. See
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<xref linkend="regress-variant"> for details.
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</para>
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<sect2>
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<title>Error message differences</title>
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<para>
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Some of the regression tests involve intentional invalid input
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values. Error messages can come from either the
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<productname>PostgreSQL</productname> code or from the host
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platform system routines. In the latter case, the messages can
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vary between platforms, but should reflect similar
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information. These differences in messages will result in a
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<quote>failed</quote> regression test that can be validated by
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inspection.
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</para>
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</sect2>
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<sect2>
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<title>Locale differences</title>
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<para>
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If you run the tests against an already-installed server that was
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initialized with a collation-order locale other than C, then
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there might be differences due to sort order and follow-up
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failures. The regression test suite is set up to handle this
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problem by providing alternative result files that together are
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known to handle a large number of locales.
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</para>
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</sect2>
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<sect2>
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<title>Date and time differences</title>
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<para>
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Most of the date and time results are dependent on the time zone
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environment. The reference files are generated for time zone
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<literal>PST8PDT</literal> (Berkeley, California), and there will be
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apparent failures if the tests are not run with that time zone setting.
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The regression test driver sets environment variable
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<envar>PGTZ</envar> to <literal>PST8PDT</literal>, which normally
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ensures proper results.
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</para>
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</sect2>
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<sect2>
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<title>Floating-point differences</title>
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<para>
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Some of the tests involve computing 64-bit floating-point numbers (<type>double
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precision</type>) from table columns. Differences in
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results involving mathematical functions of <type>double
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precision</type> columns have been observed. The <literal>float8</> and
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<literal>geometry</> tests are particularly prone to small differences
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across platforms, or even with different compiler optimization options.
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Human eyeball comparison is needed to determine the real
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significance of these differences which are usually 10 places to
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the right of the decimal point.
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</para>
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<para>
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Some systems display minus zero as <literal>-0</>, while others
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just show <literal>0</>.
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</para>
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<para>
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Some systems signal errors from <function>pow()</function> and
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<function>exp()</function> differently from the mechanism
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expected by the current <productname>PostgreSQL</productname>
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code.
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</para>
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</sect2>
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<sect2>
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<title>Row ordering differences</title>
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<para>
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You might see differences in which the same rows are output in a
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different order than what appears in the expected file. In most cases
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this is not, strictly speaking, a bug. Most of the regression test
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scripts are not so pedantic as to use an <literal>ORDER BY</> for every single
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<literal>SELECT</>, and so their result row orderings are not well-defined
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according to the letter of the SQL specification. In practice, since we are
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looking at the same queries being executed on the same data by the same
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software, we usually get the same result ordering on all platforms, and
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so the lack of <literal>ORDER BY</> isn't a problem. Some queries do exhibit
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cross-platform ordering differences, however. When testing against an
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already-installed server, ordering differences can also be caused by
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non-C locale settings or non-default parameter settings, such as custom values
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of <varname>work_mem</> or the planner cost parameters.
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</para>
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<para>
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Therefore, if you see an ordering difference, it's not something to
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worry about, unless the query does have an <literal>ORDER BY</> that your
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result is violating. But please report it anyway, so that we can add an
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<literal>ORDER BY</> to that particular query and thereby eliminate the bogus
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<quote>failure</quote> in future releases.
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</para>
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<para>
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You might wonder why we don't order all the regression test queries explicitly
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to get rid of this issue once and for all. The reason is that that would
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make the regression tests less useful, not more, since they'd tend
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to exercise query plan types that produce ordered results to the
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exclusion of those that don't.
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</para>
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</sect2>
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<sect2>
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<title>Insufficient stack depth</title>
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<para>
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If the <literal>errors</literal> test results in a server crash
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at the <literal>select infinite_recurse()</> command, it means that
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the platform's limit on process stack size is smaller than the
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<![%standalone-ignore;[<xref linkend="guc-max-stack-depth">]]>
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<![%standalone-include;[<literal>max_stack_depth</literal>]]>
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parameter indicates. This
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can be fixed by running the server under a higher stack
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size limit (4MB is recommended with the default value of
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<varname>max_stack_depth</>). If you are unable to do that, an
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alternative is to reduce the value of <varname>max_stack_depth</>.
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</para>
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</sect2>
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<sect2>
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<title>The <quote>random</quote> test</title>
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<para>
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The <literal>random</literal> test script is intended to produce
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random results. In rare cases, this causes the random regression
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test to fail. Typing:
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<programlisting>
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diff results/random.out expected/random.out
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</programlisting>
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should produce only one or a few lines of differences. You need
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not worry unless the random test fails repeatedly.
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</para>
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</sect2>
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</sect1>
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<!-- We might want to move the following section into the developer's guide. -->
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<sect1 id="regress-variant">
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<title>Variant Comparison Files</title>
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<para>
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Since some of the tests inherently produce environment-dependent
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results, we have provided ways to specify alternative <quote>expected</>
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result files. Each regression test can have several comparison files
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showing possible results on different platforms. There are two
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independent mechanisms for determining which comparison file is used
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for each test.
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</para>
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<para>
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The first mechanism allows comparison files to be selected for
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specific platforms. There is a mapping file,
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<filename>src/test/regress/resultmap</filename>, that defines
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which comparison file to use for each platform.
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To eliminate bogus test <quote>failures</quote> for a particular platform,
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you first choose or make a variant result file, and then add a line to the
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<filename>resultmap</filename> file.
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</para>
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<para>
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Each line in the mapping file is of the form
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<synopsis>
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testname:output:platformpattern=comparisonfilename
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</synopsis>
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The test name is just the name of the particular regression test
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module. The output value indicates which output file to check. For the
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standard regression tests, this is always <literal>out</literal>. The
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value corresponds to the file extension of the output file.
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The platform pattern is a pattern in the style of the Unix
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tool <command>expr</> (that is, a regular expression with an implicit
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<literal>^</literal> anchor at the start). It is matched against the
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platform name as printed by <command>config.guess</command>.
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The comparison file name is the base name of the substitute result
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comparison file.
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</para>
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<para>
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For example: some systems interpret very small floating-point values
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as zero, rather than reporting an underflow error. This causes a
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few differences in the <filename>float8</> regression test.
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Therefore, we provide a variant comparison file,
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<filename>float8-small-is-zero.out</filename>, which includes
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the results to be expected on these systems. To silence the bogus
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<quote>failure</quote> message on <systemitem>OpenBSD</systemitem>
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platforms, <filename>resultmap</filename> includes:
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<programlisting>
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float8:out:i.86-.*-openbsd=float8-small-is-zero.out
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</programlisting>
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which will trigger on any machine for which the output of
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<command>config.guess</command> matches <literal>i.86-.*-openbsd</literal>.
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Other lines
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in <filename>resultmap</> select the variant comparison file for other
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platforms where it's appropriate.
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</para>
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<para>
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The second selection mechanism for variant comparison files is
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much more automatic: it simply uses the <quote>best match</> among
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several supplied comparison files. The regression test driver
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script considers both the standard comparison file for a test,
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<literal><replaceable>testname</>.out</>, and variant files named
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<literal><replaceable>testname</>_<replaceable>digit</>.out</>
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(where the <replaceable>digit</> is any single digit
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<literal>0</>-<literal>9</>). If any such file is an exact match,
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the test is considered to pass; otherwise, the one that generates
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the shortest diff is used to create the failure report. (If
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<filename>resultmap</filename> includes an entry for the particular
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test, then the base <replaceable>testname</> is the substitute
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name given in <filename>resultmap</filename>.)
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</para>
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<para>
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For example, for the <literal>char</literal> test, the comparison file
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<filename>char.out</filename> contains results that are expected
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in the <literal>C</> and <literal>POSIX</> locales, while
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the file <filename>char_1.out</filename> contains results sorted as
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they appear in many other locales.
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</para>
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<para>
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The best-match mechanism was devised to cope with locale-dependent
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results, but it can be used in any situation where the test results
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cannot be predicted easily from the platform name alone. A limitation of
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this mechanism is that the test driver cannot tell which variant is
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actually <quote>correct</> for the current environment; it will just pick
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the variant that seems to work best. Therefore it is safest to use this
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mechanism only for variant results that you are willing to consider
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equally valid in all contexts.
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</para>
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</sect1>
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</chapter>
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