606 lines
24 KiB
Plaintext
606 lines
24 KiB
Plaintext
<!-- doc/src/sgml/regress.sgml -->
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<chapter id="regress">
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<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 alone, while 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.
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</para>
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<sect2>
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<title>Running the Tests Against a Temporary Installation</title>
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<para>
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To run the parallel 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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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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</sect2>
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<sect2>
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<title>Running the Tests Against an Existing Installation</title>
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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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</sect2>
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<sect2>
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<title>Testing Hot Standby</title>
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<para>
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The source distribution also contains regression tests of the static
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behavior of Hot Standby. These tests require a running primary server
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and a running standby server that is accepting new WAL changes from the
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primary using either file-based log shipping or streaming replication.
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Those servers are not automatically created for you, nor is the setup
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documented here. Please check the various sections of the documentation already
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devoted to the required commands and related issues.
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</para>
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<para>
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First create a database called "regression" on the primary.
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<screen>
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psql -h primary -c "CREATE DATABASE regression"
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</screen>
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Next, run a preparatory script on the primary in the regression database:
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<filename>src/test/regress/sql/hs_primary_setup.sql</filename>, and
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allow for the changes to propagate to the standby, for example
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<screen>
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psql -h primary -f src/test/regress/sql/hs_primary_setup.sql regression
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</screen>
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Now confirm that the default connection for the tester is the standby
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server under test and then run the <literal>standbycheck</> target from the regression
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directory:
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<screen>
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cd src/test/regress
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gmake standbycheck
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</screen>
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</para>
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<para>
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Some extreme behaviors can also be generated on the primary using the
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script: <filename>src/test/regress/sql/hs_primary_extremes.sql</filename>
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to allow the behavior of the standby to be tested.
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</para>
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<para>
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Additional automated testing may be available in later releases.
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</para>
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</sect2>
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<sect2>
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<title>Locale and Encoding</title>
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<para>
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By default, the tests against a temporary installation use the
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locale defined in the current environment and the corresponding
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database encoding as determined by <command>initdb</command>. It
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can be useful to test different locales by setting the appropriate
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environment variables, for example:
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<screen>
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gmake check LANG=C
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gmake check LC_COLLATE=en_US.utf8 LC_CTYPE=fr_CA.utf8
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</screen>
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For implementation reasons, setting <envar>LC_ALL</envar> does not
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work for this purpose; all the other locale-related environment
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variables do work.
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</para>
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<para>
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When testing against an existing installation, the locale is
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determined by the existing database cluster and cannot be set
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separately for the test run.
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</para>
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<para>
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You can also choose the database encoding explicitly by setting
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the variable <envar>ENCODING</envar>, for example:
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<screen>
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gmake check LANG=C ENCODING=EUC_JP
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</screen>
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Setting the database encoding this way typically only makes sense
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if the locale is C; otherwise the encoding is chosen automatically
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from the locale, and specifying an encoding that does not match
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the locale will result in an error.
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</para>
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<para>
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The encoding can be set for tests against a temporary or an
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existing installation.
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</para>
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</sect2>
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<sect2>
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<title>Extra Tests</title>
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<para>
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The regression test suite contains a few test files that are not
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run by default, because they might be platform-dependent or take a
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very long time to run. You can run these or other extra test
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files by setting the variable <envar>EXTRA_TESTS</envar>. For
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example, to run the <literal>numeric_big</literal> test:
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<screen>
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gmake check EXTRA_TESTS=numeric_big
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</screen>
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To run the collation tests:
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<screen>
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gmake check EXTRA_TESTS=collate.linux.utf8 LANG=en_US.utf8
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</screen>
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The <literal>collate.linux.utf8</> test works only on Linux/glibc
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platforms, and only when run in a database that uses UTF-8 encoding.
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</para>
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</sect2>
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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>. If you don't
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like the <command>diff</command> options that are used by default, set the
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environment variable <envar>PG_REGRESS_DIFF_OPTS</envar>, for
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instance <literal>PG_REGRESS_DIFF_OPTS='-u'</literal>. (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 a 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 subsequent
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failures. The regression test suite is set up to handle this
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problem by providing alternate 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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<para>
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To run the tests in a different locale when using the
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temporary-installation method, pass the appropriate
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locale-related environment variables on
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the <command>make</command> command line, for example:
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<programlisting>
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gmake check LANG=de_DE.utf8
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</programlisting>
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(The regression test driver unsets <envar>LC_ALL</envar>, so it
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does not work to choose the locale using that variable.) To use
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no locale, either unset all locale-related environment variables
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(or set them to <literal>C</literal>) or use the following
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special invocation:
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<programlisting>
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gmake check NO_LOCALE=1
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</programlisting>
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When running the tests against an existing installation, the
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locale setup is determined by the existing installation. To
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change it, initialize the database cluster with a different
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locale by passing the appropriate options
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to <command>initdb</command>.
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</para>
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<para>
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In general, it is nevertheless advisable to try to run the
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regression tests in the locale setup that is wanted for
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production use, as this will exercise the locale- and
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encoding-related code portions that will actually be used in
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production. Depending on the operating system environment, you
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might get failures, but then you will at least know what
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locale-specific behaviors to expect when running real
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applications.
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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 setting.
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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 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,
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so the lack of <literal>ORDER BY</> is not 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. However, please report it anyway, so that we can add an
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<literal>ORDER BY</> to that particular query to 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 alternate <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>
|
|
testname:output:platformpattern=comparisonfilename
|
|
</synopsis>
|
|
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 <literal>out</literal>. The
|
|
value corresponds to the file extension of the output file.
|
|
The platform pattern is a pattern in the style of the Unix
|
|
tool <command>expr</> (that is, a regular expression with an implicit
|
|
<literal>^</literal> anchor at the start). It is matched against the
|
|
platform name as printed by <command>config.guess</command>.
|
|
The comparison file name is the base name of the substitute result
|
|
comparison file.
|
|
</para>
|
|
|
|
<para>
|
|
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 <filename>float8</> regression test.
|
|
Therefore, we provide a variant comparison file,
|
|
<filename>float8-small-is-zero.out</filename>, which includes
|
|
the results to be expected on these systems. To silence the bogus
|
|
<quote>failure</quote> message on <systemitem>OpenBSD</systemitem>
|
|
platforms, <filename>resultmap</filename> includes:
|
|
<programlisting>
|
|
float8:out:i.86-.*-openbsd=float8-small-is-zero.out
|
|
</programlisting>
|
|
which will trigger on any machine where the output of
|
|
<command>config.guess</command> matches <literal>i.86-.*-openbsd</literal>.
|
|
Other lines
|
|
in <filename>resultmap</> select the variant comparison file for other
|
|
platforms where it's appropriate.
|
|
</para>
|
|
|
|
<para>
|
|
The second selection mechanism for variant comparison files is
|
|
much more automatic: it simply uses the <quote>best match</> among
|
|
several supplied comparison files. The regression test driver
|
|
script considers both the standard comparison file for a test,
|
|
<literal><replaceable>testname</>.out</>, and variant files named
|
|
<literal><replaceable>testname</>_<replaceable>digit</>.out</>
|
|
(where the <replaceable>digit</> is any single digit
|
|
<literal>0</>-<literal>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
|
|
<filename>resultmap</filename> includes an entry for the particular
|
|
test, then the base <replaceable>testname</> is the substitute
|
|
name given in <filename>resultmap</filename>.)
|
|
</para>
|
|
|
|
<para>
|
|
For example, for the <literal>char</literal> test, the comparison file
|
|
<filename>char.out</filename> contains results that are expected
|
|
in the <literal>C</> and <literal>POSIX</> locales, while
|
|
the file <filename>char_1.out</filename> contains results sorted as
|
|
they appear in many other locales.
|
|
</para>
|
|
|
|
<para>
|
|
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 <quote>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.
|
|
</para>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="regress-coverage">
|
|
<title>Test Coverage Examination</title>
|
|
|
|
<para>
|
|
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 <command>gcov</command>
|
|
and <command>lcov</command> programs.
|
|
</para>
|
|
|
|
<para>
|
|
A typical workflow would look like this:
|
|
<screen>
|
|
./configure --enable-coverage ... OTHER OPTIONS ...
|
|
gmake
|
|
gmake check # or other test suite
|
|
gmake coverage-html
|
|
</screen>
|
|
Then point your HTML browser
|
|
to <filename>coverage/index.html</filename>.
|
|
The <command>gmake</command> commands also work in subdirectories.
|
|
</para>
|
|
|
|
<para>
|
|
To reset the execution counts between test runs, run:
|
|
<screen>
|
|
gmake coverage-clean
|
|
</screen>
|
|
</para>
|
|
</sect1>
|
|
|
|
</chapter>
|