[orm-devel] count vs len()

[Diedrich Vorberg]

>> SelectResults do have a len(), see next question.
>
>I was thinking that on large tables fetchall could be inefficient if the
>length is the only data point required.  I recently noticed the
>DelayedResult and was thinking maybe this could yield similar results
>without a potentially expensive select statement.  I'll investigate further.
>For now I'm just using the execute for the custom statement (brittle, yes
>:) ):
>
>        cursor = conn.execute("SELECT COUNT(*) FROM map_items")
>        return cursor.rowcount

See datasource.py:711: queryResult::__len__() It does the same thing!
The comment on the function is no longer accurate: psycopg _does_
provide rowcount!

  result = ds.select(model.map_item)
  return len(result)

Diedrich

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