This patch is based on

http://gborg.postgresql.org/pipermail/pgjdbc-commit/2005-November/000416.html

but omitting some changes relevant to logging.  The changes are

    Add a new parameter 'stringtype' (values 'varchar' or 'unspecified') to

    control how parameters set via setString() are bound.

    Make compatible=7.4 use stringtype=unspecified.

    Rename Oid.INVALID -> Oid.UNSPECIFIED.

    Fix V3 parameter logic so that prepared statements are not reused when a

    non-NULL UNSPECIFIED parameter is set over the top of a previous

    parameter.

    Change testTypeChange() so it works with stringtype=unspecified.

The stringtype=unspecified option is really important to minimize problems

for applications being ported forward from the 7.4 postgresql JDBC driver.

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/Driver.java.in postgresql-jdbc-8.1-405.src/org/postgresql/Driver.java.in

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/Driver.java.in	2005-02-15 03:56:24.000000000 -0500

+++ postgresql-jdbc-8.1-405.src/org/postgresql/Driver.java.in	2006-02-17 19:19:50.000000000 -0500

@@ -420,9 +420,12 @@

                   "When connecting to a pre-7.3 server, the database encoding to assume is in use." },

                 { "compatible", Boolean.FALSE,

                   "Force compatibility of some features with an older version of the driver.",

-                  new String[] { "7.1", "7.2", "7.3" } },

+                  new String[] { "7.1", "7.2", "7.3", "7.4", "8.0", "8.1" } },

                 { "loginTimeout", Boolean.FALSE,

-                  "The login timeout, in seconds; 0 means no timeout beyond the normal TCP connection timout." }

+                  "The login timeout, in seconds; 0 means no timeout beyond the normal TCP connection timout." },

+                { "stringtype", Boolean.FALSE,

+                  "The type to bind String parameters as (usually 'varchar'; 'unspecified' allows implicit casting to other types)",

+                  new String[] { "varchar", "unspecified" } },

             };

     /**

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/BaseConnection.java postgresql-jdbc-8.1-405.src/org/postgresql/core/BaseConnection.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/BaseConnection.java	2005-08-01 02:54:14.000000000 -0400

+++ postgresql-jdbc-8.1-405.src/org/postgresql/core/BaseConnection.java	2006-02-17 19:19:50.000000000 -0500

@@ -143,4 +143,7 @@

     // Ew. Quick hack to give access to the connection-specific utils implementation.

     public TimestampUtils getTimestampUtils();

+

+    // Get the bind-string-as-varchar config flag

+    public boolean getStringVarcharFlag();

 }

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/Oid.java postgresql-jdbc-8.1-405.src/org/postgresql/core/Oid.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/Oid.java	2005-07-04 14:50:28.000000000 -0400

+++ postgresql-jdbc-8.1-405.src/org/postgresql/core/Oid.java	2006-02-17 19:19:50.000000000 -0500

@@ -14,7 +14,7 @@

  * use.

  */

 public class Oid {

-    public static final int INVALID = 0;

+    public static final int UNSPECIFIED = 0;

     public static final int INT2 = 21;

     public static final int INT4 = 23;

     public static final int INT8 = 20;

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/v3/SimpleParameterList.java postgresql-jdbc-8.1-405.src/org/postgresql/core/v3/SimpleParameterList.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/core/v3/SimpleParameterList.java	2005-07-08 13:38:29.000000000 -0400

+++ postgresql-jdbc-8.1-405.src/org/postgresql/core/v3/SimpleParameterList.java	2006-02-17 19:19:50.000000000 -0500

@@ -62,10 +62,11 @@

         paramValues[index] = value ;

         direction[index] |= IN;

-        // If we are setting something to null, don't overwrite our existing type

-        // for it.  We don't need the correct type info to send NULL and we

-        // don't want to overwrite and require a reparse.

-        if (oid == Oid.INVALID && paramTypes[index] != Oid.INVALID)

+        // If we are setting something to an UNSPECIFIED NULL, don't overwrite

+        // our existing type for it.  We don't need the correct type info to

+        // send this value, and we don't want to overwrite and require a

+        // reparse.

+        if (oid == Oid.UNSPECIFIED && paramTypes[index] != Oid.UNSPECIFIED && value == NULL_OBJECT)

             return;

         paramTypes[index] = oid;

@@ -170,7 +171,7 @@

     boolean hasUnresolvedTypes() {

         for (int i=0; i< paramTypes.length; i++) {

-            if (paramTypes[i] == Oid.INVALID)

+            if (paramTypes[i] == Oid.UNSPECIFIED)

                 return true;

         }

         return false;

@@ -178,7 +179,7 @@

     void setResolvedType(int index, int oid) {

         // only allow overwriting an unknown value

-        if (paramTypes[index-1] == Oid.INVALID) {

+        if (paramTypes[index-1] == Oid.UNSPECIFIED) {

             paramTypes[index-1] = oid;

         } else if (paramTypes[index-1] != oid) {

             throw new IllegalArgumentException("Can't change resolved type for param: " + index + " from " + paramTypes[index] + " to " + oid);

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/AbstractJdbc2Connection.java postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/AbstractJdbc2Connection.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/AbstractJdbc2Connection.java	2005-08-01 02:54:14.000000000 -0400

+++ postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/AbstractJdbc2Connection.java	2006-02-17 19:19:50.000000000 -0500

@@ -58,6 +58,9 @@

     // Connection's readonly state.

     public boolean readOnly = false;

+    // Bind String to UNSPECIFIED or VARCHAR?

+    public final boolean bindStringAsVarchar;

+

     // Current warnings; there might be more on protoConnection too.

     public SQLWarning firstWarning = null;

@@ -124,6 +127,23 @@

             Driver.debug("    prepare threshold = " + prepareThreshold);

         }

+        //

+        // String -> text or unknown?

+        //

+

+        String stringType = info.getProperty("stringtype");

+        if (stringType != null) {

+            if (stringType.equalsIgnoreCase("unspecified"))

+                bindStringAsVarchar = false;

+            else if (stringType.equalsIgnoreCase("varchar"))

+                bindStringAsVarchar = true;

+            else

+                throw new PSQLException(GT.tr("Unsupported value for stringtype parameter: {0}", stringType),

+                                        PSQLState.INVALID_PARAMETER_VALUE);

+        } else {

+            bindStringAsVarchar = haveMinimumCompatibleVersion("8.0");

+        }

+

         // Initialize timestamp stuff

         timestampUtils = new TimestampUtils(haveMinimumServerVersion("7.4"));

@@ -1033,5 +1053,9 @@

     {

         return protoConnection.getProtocolVersion();

     }

-}

+    public boolean getStringVarcharFlag()

+    {

+        return bindStringAsVarchar;

+    }

+}

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/AbstractJdbc2Statement.java postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/AbstractJdbc2Statement.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/AbstractJdbc2Statement.java	2006-02-01 13:52:30.000000000 -0500

+++ postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/AbstractJdbc2Statement.java	2006-02-17 19:19:50.000000000 -0500

@@ -1066,7 +1066,7 @@

         case Types.STRUCT:

         case Types.NULL:

         case Types.OTHER:

-            oid = Oid.INVALID;

+            oid = Oid.UNSPECIFIED;

             break;

         default:

             // Bad Types value.

@@ -1206,7 +1206,7 @@

     public void setString(int parameterIndex, String x) throws SQLException

     {

         checkClosed();

-        setString(parameterIndex, x, Oid.VARCHAR);

+        setString(parameterIndex, x, (connection.getStringVarcharFlag() ? Oid.VARCHAR : Oid.UNSPECIFIED));

     }

     protected void setString(int parameterIndex, String x, int oid) throws SQLException

@@ -1519,7 +1519,7 @@

     private void setPGobject(int parameterIndex, PGobject x) throws SQLException {

         String typename = x.getType();

         int oid = connection.getPGType(typename);

-        if (oid == Oid.INVALID)

+        if (oid == Oid.UNSPECIFIED)

             throw new PSQLException(GT.tr("Unknown type {0}.", typename), PSQLState.INVALID_PARAMETER_TYPE);

         setString(parameterIndex, x.getValue(), oid);

@@ -1585,7 +1585,7 @@

 	            break;

 	        case Types.VARCHAR:

 	        case Types.LONGVARCHAR:

-	            setString(parameterIndex, pgType.toString());

+	            setString(parameterIndex, pgType.toString(), Oid.VARCHAR);

 	            break;

 	        case Types.DATE:

 	            if (in instanceof java.sql.Date)

@@ -2681,7 +2681,7 @@

         // backend looks for array types.

         String typename = "_" + x.getBaseTypeName();

         int oid = connection.getPGType(typename);

-        if (oid == Oid.INVALID)

+        if (oid == Oid.UNSPECIFIED)

             throw new PSQLException(GT.tr("Unknown type {0}.", typename), PSQLState.INVALID_PARAMETER_TYPE);

         setString(i, x.toString(), oid);

@@ -2882,7 +2882,7 @@

         if (cal != null)

             cal = (Calendar)cal.clone();

-        // We must use INVALID here, or inserting a Date-with-timezone into a

+        // We must use UNSPECIFIED here, or inserting a Date-with-timezone into a

         // timestamptz field does an unexpected rotation by the server's TimeZone:

         //

         // We want to interpret 2005/01/01 with calendar +0100 as

@@ -2901,7 +2901,7 @@

         //  2005-01-01 00:00:00+03

         // (1 row)

-        bindString(i, connection.getTimestampUtils().toString(cal, d), Oid.INVALID);

+        bindString(i, connection.getTimestampUtils().toString(cal, d), Oid.UNSPECIFIED);

     }

     public void setTime(int i, Time t, java.util.Calendar cal) throws SQLException

@@ -2917,9 +2917,7 @@

         if (cal != null)

             cal = (Calendar)cal.clone();

-        // We don't need INVALID here as we only support inserting a Time into

-        // 'time' and 'timetz' columns.

-        bindString(i, connection.getTimestampUtils().toString(cal, t), Oid.INVALID);

+        bindString(i, connection.getTimestampUtils().toString(cal, t), Oid.UNSPECIFIED);

     }

     public void setTimestamp(int i, Timestamp t, java.util.Calendar cal) throws SQLException

@@ -2934,7 +2932,7 @@

         if (cal != null)

             cal = (Calendar)cal.clone();

-        // Use INVALID as a compromise to get both TIMESTAMP and TIMESTAMPTZ working.

+        // Use UNSPECIFIED as a compromise to get both TIMESTAMP and TIMESTAMPTZ working.

         // This is because you get this in a +1300 timezone:

         // 

         // template1=# select '2005-01-01 15:00:00 +1000'::timestamptz;

@@ -2961,10 +2959,10 @@

         // time compared to the string we originally provided. But going straight

         // to timestamp is OK as the input parser for timestamp just throws away

         // the timezone part entirely. Since we don't know ahead of time what type

-        // we're actually dealing with, INVALID seems the lesser evil, even if it

+        // we're actually dealing with, UNSPECIFIED seems the lesser evil, even if it

         // does give more scope for type-mismatch errors being silently hidden.

-        bindString(i, connection.getTimestampUtils().toString(cal, t), Oid.INVALID); // Let the server infer the right type.

+        bindString(i, connection.getTimestampUtils().toString(cal, t), Oid.UNSPECIFIED); // Let the server infer the right type.

     }

     // ** JDBC 2 Extensions for CallableStatement**

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/TypeInfoCache.java postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/TypeInfoCache.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/jdbc2/TypeInfoCache.java	2006-02-09 11:29:20.000000000 -0500

+++ postgresql-jdbc-8.1-405.src/org/postgresql/jdbc2/TypeInfoCache.java	2006-02-17 19:19:50.000000000 -0500

@@ -140,7 +140,7 @@

         if (!((BaseStatement)_getOidStatement).executeWithFlags(QueryExecutor.QUERY_SUPPRESS_BEGIN))

             throw new PSQLException(GT.tr("No results were returned by the query."), PSQLState.NO_DATA);

-        oid = new Integer(Oid.INVALID);

+        oid = new Integer(Oid.UNSPECIFIED);

         ResultSet rs = _getOidStatement.getResultSet();

         if (rs.next()) {

             oid = new Integer(rs.getInt(1));

@@ -154,7 +154,7 @@

     public String getPGType(int oid) throws SQLException

     {

-        if (oid == Oid.INVALID)

+        if (oid == Oid.UNSPECIFIED)

             return null;

         String pgTypeName = (String)_oidToPgName.get(new Integer(oid));

diff -Naur postgresql-jdbc-8.1-405.src.orig/org/postgresql/test/jdbc2/ServerPreparedStmtTest.java postgresql-jdbc-8.1-405.src/org/postgresql/test/jdbc2/ServerPreparedStmtTest.java

--- postgresql-jdbc-8.1-405.src.orig/org/postgresql/test/jdbc2/ServerPreparedStmtTest.java	2005-01-27 17:50:17.000000000 -0500

+++ postgresql-jdbc-8.1-405.src/org/postgresql/test/jdbc2/ServerPreparedStmtTest.java	2006-02-17 19:19:50.000000000 -0500

@@ -256,7 +256,7 @@

     }

     public void testTypeChange() throws Exception {

-        PreparedStatement pstmt = con.prepareStatement("SELECT ?");

+        PreparedStatement pstmt = con.prepareStatement("SELECT CAST (? AS TEXT)");

         ((PGStatement)pstmt).setUseServerPrepare(true);

         // Prepare with int parameter.