Discuss LOCALE differences as a reason for regression test failure.

doc/src/sgml/regress.sgml

@@ -1,4 +1,4 @@
-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/regress.sgml,v 1.16 2001/01/02 05:56:02 tgl Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/regress.sgml,v 1.17 2001/03/20 00:09:36 tgl Exp $ -->
 
  <chapter id="regress">
   <title id="regress-title">Regression Tests</title>
@@ -49,7 +49,7 @@
 <screen>
 <computeroutput>
 ======================
- All 75 tests passed.
+ All 76 tests passed.
 ======================
 </computeroutput>
 </screen>
@@ -64,6 +64,7 @@
     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,
 <screen>
 <prompt>root# </prompt><userinput>chmod -R a+w src/test/regress</userinput>
 <prompt>root# </prompt><userinput>su - joeuser</userinput>
@@ -100,8 +101,9 @@
 <screen>
 <prompt>$ </prompt><userinput>gmake installcheck</userinput>
 </screen>
-   The server is expected to be running on the local host with the
-   default port number.
+   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.
   </para>
 
   <sect1 id="regress-evaluation">
@@ -111,8 +113,8 @@
     Some properly installed and fully functional
     <productname>PostgreSQL</productname> installations can
     <quote>fail</quote> some of these regression tests due to
-    artifacts of floating point representation and time zone
-    support. The tests are currently evaluated using a simple
+    platform-specific artifacts such as varying floating point representation
+    and time zone support. The tests are currently evaluated using a simple
     <application>diff</application> comparison against the outputs
     generated on a reference system, so the results are sensitive to
     small system differences.  When a test is reported as
@@ -149,6 +151,29 @@
     </para>
    </sect2>
     
+   <sect2>
+    <title>Locale differences</title>
+
+    <para>
+     The tests expect to run in plain <quote>C</quote> locale.  This
+     should not cause any problems when you run the tests against a
+     temporary installation, since the regression test driver takes care
+     to start the server in C locale.  However, if you run the tests
+     against an already-installed server that is using non-C locale settings,
+     you may see differences caused by varying rules for string sort order,
+     formatting of numeric and monetary values, and so forth.
+    </para>
+
+    <para>
+     In some locales the resulting differences are small and easily checked by
+     inspection.  However, in a locale that changes the rules for formatting
+     of numeric values (typically by swapping the usage of commas and
+     decimal points), entry of some data values will fail, resulting in
+     extensive differences later in the tests where the missing data values
+     are supposed to be used.
+    </para>
+   </sect2>
+    
    <sect2>
     <title>Date and time differences</title>
       
@@ -262,13 +287,14 @@ according to the letter of the SQL spec.  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.
+cross-platform ordering differences, however.  (Ordering differences
+can also be triggered by non-C locale settings.)
     </para>
 
     <para>
 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
+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
 <quote>failure</quote> in future releases.
     </para>