title: PostgreSQL array_agg(INTEGER[])
body: <p>Using Postgres 9.5, I want to concaternate integer arrays from a GROUP BY. From the documentation is seems as though array_agg should be able to do this, but I get: <code>ERROR:  cannot accumulate arrays of different dimensionality</code></p>
  
  <p>Using array_dims on my test set I get [1:18], [1:24] and [1:48]. I see this as 3 1-dimensional arrays of different lengths. The result should be a single array with dimension [1:90] What am I missing here?</p>