Index: src/core/qgsdatasourceuri.cpp
===================================================================
--- src/core/qgsdatasourceuri.cpp	(revision 10147)
+++ src/core/qgsdatasourceuri.cpp	(working copy)
@@ -136,6 +136,10 @@
       {
         mPort = pval;
       }
+      else if ( pname == "key" )
+      {
+        mKey = pval;
+      }
       else if ( pname == "tty" )
       {
         QgsDebugMsg( "backend debug tty ignored" );
@@ -189,6 +193,11 @@
   return mGeometryColumn;
 }
 
+QString QgsDataSourceURI::key() const
+{
+  return mKey;
+}
+
 void QgsDataSourceURI::setSql( QString sql )
 {
   mSql = sql;
@@ -298,11 +307,14 @@
 
 QString QgsDataSourceURI::uri() const
 {
-  return connectionInfo()
-         + QString( " table=%1 (%2) sql=%3" )
+  QString r(connectionInfo());
+  if (!mKey.isEmpty())
+	  r += QString( " key=%1" ).arg(mKey);
+  r += QString( " table=%1 (%2) sql=%3" )
          .arg( quotedTablename() )
          .arg( mGeometryColumn )
          .arg( mSql );
+  return r;
 }
 
 QString QgsDataSourceURI::quotedTablename() const
@@ -329,10 +341,12 @@
 void QgsDataSourceURI::setDataSource( const QString &schema,
                                       const QString &table,
                                       const QString &geometryColumn,
-                                      const QString &sql )
+                                      const QString &sql,
+                                      const QString &key )
 {
   mSchema = schema;
   mTable = table;
   mGeometryColumn = geometryColumn;
   mSql = sql;
+  mKey = key;
 }
Index: src/core/qgsdatasourceuri.h
===================================================================
--- src/core/qgsdatasourceuri.h	(revision 10147)
+++ src/core/qgsdatasourceuri.h	(working copy)
@@ -58,13 +58,15 @@
     void setDataSource( const QString& aSchema,
                         const QString& aTable,
                         const QString& aGeometryColumn,
-                        const QString& aSql = QString() );
+                        const QString& aSql = QString(),
+                        const QString& aKey = QString() );
 
     QString username() const;
     QString schema() const;
     QString table() const;
     QString sql() const;
     QString geometryColumn() const;
+    QString key() const;
 
     void clearSchema();
     void setSql( QString sql );
@@ -87,6 +89,8 @@
     QString mTable;
     //! geometry column
     QString mGeometryColumn;
+    //! primary key column
+    QString mKey;
     //! SQL where clause used to limit features returned from the layer
     QString mSql;
     //! username
Index: src/providers/postgres/qgspostgresprovider.cpp
===================================================================
--- src/providers/postgres/qgspostgresprovider.cpp	(revision 10147)
+++ src/providers/postgres/qgspostgresprovider.cpp	(working copy)
@@ -74,6 +74,7 @@
   mTableName = mUri.table();
   geometryColumn = mUri.geometryColumn();
   sqlWhereClause = mUri.sql();
+  primaryKey = mUri.key();
 
   // Keep a schema qualified table name for convenience later on.
   mSchemaTableName = mUri.quotedTablename();
@@ -85,6 +86,8 @@
   QgsDebugMsg( "Geometry column is: " + geometryColumn );
   QgsDebugMsg( "Schema is: " + mSchemaName );
   QgsDebugMsg( "Table name is: " + mTableName );
+  if (!primaryKey.isEmpty())
+    QgsDebugMsg( "User-suggested primary key is: " + primaryKey );
 
   connectionRW = NULL;
   connectionRO = Conn::connectDb( mUri.connectionInfo(), true );
@@ -190,7 +193,7 @@
   loadFields();
 
   // set the primary key
-  getPrimaryKey();
+  getPrimaryKey(primaryKey);
 
   // Set the postgresql message level so that we don't get the
   // 'there is no transaction in progress' warning.
@@ -860,13 +863,46 @@
   }
 }
 
-QString QgsPostgresProvider::getPrimaryKey()
+QString QgsPostgresProvider::getPrimaryKey(const QString& suggestedKey)
 {
+  QStringList log;
+  QString sql;
+
+  // if the user has suggested a key to use, do some verification to
+  // ensure it is satisfactory
+  if (!suggestedKey.isEmpty())
+  {
+        // Get the column data type
+        sql = QString( "select pg_type.typname from pg_attribute,pg_type where atttypid=pg_type.oid and attname=%1 and attrelid=regclass(%2)" )
+              .arg( quotedValue( suggestedKey ) )
+	      .arg( quotedValue( mSchemaTableName ) );
+        Result types = connectionRO->PQexec( sql );
+
+        if ( PQntuples( types ) > 0 )
+        {
+          QString columnType = QString::fromUtf8( PQgetvalue( types, 0, 0 ) );
+
+          if ( columnType != "int4" )
+            log.append( tr( "The user suggested column '%1' is unsuitable because Qgis does not currently "
+                            "support non-int4 type columns as a key into the table.\n" ).arg( suggestedKey ) );
+          else 
+	  {
+	    primaryKey = suggestedKey;
+	    primaryKeyType = columnType;
+	    return primaryKey;
+	  }
+        }
+	else
+	{
+          QgsDebugMsg( QString("User-suggested key column %1.%2(%3) not found.").arg(mSchemaName).arg(mTables).arg(suggestedKey) );
+	}
+  }
+
   // check to see if there is an unique index on the relation, which
   // can be used as a key into the table. Primary keys are always
   // unique indices, so we catch them as well.
 
-  QString sql = QString( "select indkey from pg_index where indisunique='t' and indrelid=regclass(%1)::oid" )
+  sql = QString( "select indkey from pg_index where indisunique='t' and indrelid=regclass(%1)::oid" )
                 .arg( quotedValue( mSchemaTableName ) );
 
   QgsDebugMsg( "Getting unique index using '" + sql + "'" );
@@ -875,8 +911,6 @@
 
   QgsDebugMsg( "Got " + QString::number( PQntuples( pk ) ) + " rows." );
 
-  QStringList log;
-
   // if we got no tuples we ain't got no unique index :)
   if ( PQntuples( pk ) == 0 )
   {
Index: src/providers/postgres/qgspostgresprovider.h
===================================================================
--- src/providers/postgres/qgspostgresprovider.h	(revision 10147)
+++ src/providers/postgres/qgspostgresprovider.h	(working copy)
@@ -159,7 +159,7 @@
 
     /**  * Get the name of the primary key for the layer
     */
-    QString getPrimaryKey();
+    QString getPrimaryKey(const QString& suggestedKey = QString());
 
     /**
      * Get the field information for the layer