NoClassDefFoundError: com.google.common.collect.Sets

Error-
NoClassDefFoundError: "com.google.common.collect.Sets"

Solution-
Add guava-11.0.2.jar to WEB-INF/lib and add it to the build path.

GWT wrapper for visualization treemap with mouse events

A treemap is a helpful visualization of a data tree. It would be nice if the treemap had features like weighted box sizes for intermediate levels and explicitly setting up colors for non-leaf nodes. I wrote a  quick Google Web Toolkit(GWT) wrapper for Google visualization treemap-

 public class TreeMap extends Visualization<TreeMap.Options>
{
   public static class Options extends AbstractDrawOptions {
       public static Options create() {
           return JavaScriptObject.createObject().cast();
       }

       protected Options() { }
   }

   public static final String PACKAGE = "treemap";

   public TreeMap() {
       super();
   }

   public TreeMap(AbstractDataTable data, Options options) {
       super(data, options);
   }

   @Override
   protected native JavaScriptObject createJso(Element parent) /*-{
       return new $wnd.google.visualization.TreeMap(parent);                
   }-*/;
   
   public final void addOnMouseOverHandler(OnMouseOverHandler handler) {
       Handler.addHandler(this, "onmouseover", handler);
   }
   
   public final void addOnMouseOutHandler(OnMouseOutHandler handler) {
       Handler.addHandler(this, "onmouseout", handler);
   }
}

Postgres script - for loop two dimension array using array upper and lower

A basic script to loop over an array in psql-

CREATE OR REPLACE FUNCTION func1(n character varying, v character varying)

  RETURNS integer AS

$BODY$

    DECLARE   

       return_code integer;

    BEGIN

       RAISE NOTICE '(%,%)', n, v;          

       return_code := 1;

    RETURN return_code; 

    EXCEPTION 

        WHEN NO_DATA_FOUND THEN           
           RETURN -1;
    END;

    $BODY$

  LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION func2()

  RETURNS integer AS

$BODY$

    DECLARE      

       return_code integer;

       pairs varchar[][] := array[['key2','val2'],

                            ['key1','val2']];

    BEGIN

        FOR i IN array_lower(pairs, 1) .. array_upper(pairs, 1)

        LOOP

         --RAISE NOTICE '%,%',pairs[i][1]::varchar, pairs[i][2]::varchar;

           PERFORM func1(pairs[i][1]::varchar, pairs[i][2]::varchar);

        END LOOP;

    return 1;

    END;

    $BODY$

  LANGUAGE plpgsql;

SELECT * from func2();

Problem - GWT logging not working

When you inherit certain modules in .gwt.xml file, it disables GWT logging. This happened to me when I tried inheriting Requestfactory. Some modules inherit com.google.gwt.logging.LoggingDisabled  internally and thus affect your logging.

To fix this you should explicitly enable logging after you have inherited all your modules. At the end of your list of inherits add the following to your .gwt.xml file-

<set-property name="gwt.logging.enabled" value="TRUE"/>

Executing Postgres crosstab query as a prepared statement

I was executing a crosstab query as a prepared statement in Java(in a GWT app) and getting the following error -

PSQLException - Can't use query methods that take a query string on a PreparedStatement.

With some helpful folks from stackflow, I was able to resolve the error with the following code -

String query = "SELECT * FROM crosstab(
                      'SELECT rowid, a_name, value
                       FROM test WHERE a_name = ''att2''
                                    OR a_name = ''att3''
                      ORDER BY 1,2'

) AS ct(row_name text, cat_1 text, cat_2 text, cat_3 text);";

PreparedStatement stat = conn.prepareStatement(query);
ResultSet rs = stat.getResultSet();
//Note that, it is executeQuery() and not executeQuery(query)
stat.executeQuery();
rs = stat.getResultSet();
while (rs.next()) {
    //TODO
}




Thanks!

PostgreSQL crosstab query - Rotate a table about a pivot

An interesting feature of relational databases(postgres in this case) is the ability to rotate the table about a pivot. So if you have data like this-
 id | rowid | key | value
---+------+----+-------
  1 | test1 | key1      | val1
  2 | test1 | key2      | val2
  3 | test1 | key3      | val3
  4 | test1 | key4      | val4
  5 | test2 | key1      | val5
  6 | test2 | key2      | val6
  7 | test2 | key3      | val7
  8 | test2 | key4      | val8

And want to have a result set like this -

rowid | key1 | key2 | key3 | key4
------+------+-----+-----+------
 test1  | val1  | val2  | val3  | val4
 test2  | val5  | val6  | val7  | val8


It can be achieved by a "crosstab" query in a postgres database -

	SELECT * FROM crosstab(
	'SELECT rowid, key, value
	FROM test WHERE key= ''key1'' OR key = ''key2''
	OR key = ''key3'' OR key = ''key4''
	ORDER BY 1,2') AS
	ct(rowid text, key1 text, key2 text,
	key3 text, key4 text);

view raw crosstab.sql hosted with ❤ by GitHub

Update: 02/14/2013
The following can be achieved by a crosstab and also by an interesting SQL which I came across here - http://stackoverflow.com/questions/14863985/postgres-crosstab-maybe

	date | type | value
	_________________________
	2012-01-01 | 1 | 100
	2012-01-01 | 2 | 200
	2012-01-02 | 1 | 200
	2012-01-02 | 2 | 300
	2012-01-03 | 1 | 500
	2012-01-03 | 2 | 10

view raw gistfile1.txt hosted with ❤ by GitHub

	METHOD 1(faster):
	select date,
	sum(case when type = 1 then value end) Type1,
	sum(case when type = 2 then value end) Type2
	from yourtable
	group by date
	METHOD 2:
	select * from crosstab('select date::text, type::text,
	value::numeric(16,2) from tableA where
	type in (1,2)
	and date between ''2012-02-06'' and ''2013-02-13''
	ORDER by 1,2' )
	AS ct(date text,type1 numeric(16,2), type2 numeric(16,2))

view raw Crosstab.sql hosted with ❤ by GitHub

Virtualbox-Windows 8 developer preview installation error

Downloaded the Windows 8 developers preview yesterday but only to find I could not get it installed on a Oracle Virtualbox. I tried both 32-bit and 64 bit version on a Win 7 64 bit machine(HP EliteBook 8440p). The 32-bit got stuck at the following screen. I need to look for help on this error 0x81B8C63B

EDIT: From "Smiley"'s comments below, after I turned the Virtualization option ON from the BIOS menu at startup, I was able to install windows 8. Thanks.
Surprisingly, I have a Ubuntu virtual machine and it runs fine without turning on the Vitualization option.