PostgreSQL- getColumnName is not working, returning alias Name

Question

I'm trying to get the column name from below query,

SELECT
    category as c1,
    forecast_2016,
    category,
    rowcount,
    item_number,
    rowcount,
    category,
    avg_demand_2014_2015,
    category,
    avg_spend_2014_2015,
    avg_demand_2014_2015,
    avg_spend_2014_2015,
    demand_2015
FROM
    ag_instrument_portfolio_master LIMIT 1

Postgres version is 9.3 and Java version 1.7, java implementation is below.

stmt = con.createStatement();
rs = stmt.executeQuery(query.toString());
ResultSetMetaData columnsMetadata = rs.getMetaData();
int i = 0;
while (i < columnsMetadata.getColumnCount()) {
    i++;
    System.out.println("Name: " + columnsMetadata.getColumnName(i));
    System.out.println("Label: " + columnsMetadata.getColumnLabel(i));
}

The output is

Name: c1
Label: c1

But, expected is

Name: category
Label: c1

Answer 1

Given the comment in the pgsql-jdbc mailing list here, it appears that what you're seeing is the "as designed" behaviour of the PostgreSQL JDBC driver:

This is a limitation of the information the driver gets back from the server, it only returns the 'label' which the driver then uses for both columnname and label.

As with many other aspects of JDBC, the behaviour of a given feature can often vary depending on the implementation of a specific JDBC driver.