Remove PGINTERVALSTYLE from the set of special environment variables for

libpq.  As noted by Peter, adding this variable created a risk of unexpected
connection failures when talking to older server versions, and since it
doesn't do anything you can't do with PGOPTIONS, it doesn't seem really
necessary.  Removing it does occasion a few extra lines in pg_regress.c,
but saving a getenv() call per libpq connection attempt is perhaps worth
that anyway.

doc/src/sgml/libpq.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.270 2008/11/14 22:58:51 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.271 2008/11/25 19:30:42 tgl Exp $ -->
 
 <chapter id="libpq">
  <title><application>libpq</application> - C Library</title>
@@ -5820,17 +5820,6 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough)
      </para>
     </listitem>
 
-    <listitem>
-     <para>
-      <indexterm>
-       <primary><envar>PGINTERVALSTYLE</envar></primary>
-      </indexterm>
-      <envar>PGINTERVALSTYLE</envar> sets the default style of interval
-      representation.  (Equivalent to <literal>SET intervalstyle TO
-      ...</literal>.)
-     </para>
-    </listitem>
-
     <listitem>
      <para>
       <indexterm>

src/interfaces/libpq/fe-connect.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.368 2008/11/13 09:45:24 mha Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.369 2008/11/25 19:30:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -213,9 +213,6 @@ static const PQEnvironmentOption EnvironmentOptions[] =
 	{
 		"PGDATESTYLE", "datestyle"
 	},
-	{
-		"PGINTERVALSTYLE", "intervalstyle"
-	},
 	{
 		"PGTZ", "timezone"
 	},

src/test/regress/pg_regress.c

@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/test/regress/pg_regress.c,v 1.51 2008/11/25 11:49:35 petere Exp $
+ * $PostgreSQL: pgsql/src/test/regress/pg_regress.c,v 1.52 2008/11/25 19:30:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -716,7 +716,23 @@ initialize_environment(void)
 	 */
 	putenv("PGTZ=PST8PDT");
 	putenv("PGDATESTYLE=Postgres, MDY");
-	putenv("PGINTERVALSTYLE=postgres_verbose");
+
+	/*
+	 * Likewise set intervalstyle to ensure consistent results.  This is a
+	 * bit more painful because we must use PGOPTIONS, and we want to preserve
+	 * the user's ability to set other variables through that.
+	 */
+	{
+		const char *my_pgoptions = "--intervalstyle=postgres_verbose";
+		const char *old_pgoptions = getenv("PGOPTIONS");
+		char   *new_pgoptions;
+
+		if (!old_pgoptions)
+			old_pgoptions = "";
+		new_pgoptions = malloc(strlen(old_pgoptions) + strlen(my_pgoptions) + 12);
+		sprintf(new_pgoptions, "PGOPTIONS=%s %s", old_pgoptions, my_pgoptions);
+		putenv(new_pgoptions);
+	}
 
 	if (temp_install)
 	{