On 5/16/06, Martijn van Oosterhout <kleptog@svana.org> wrote:
> On Tue, May 16, 2006 at 09:15:13AM +0530, Gurjeet Singh wrote:
> As has been pointed out, aliases ave always been displayed. The OPs
> problem was that he was using schema.tablename everywhere and explain
> didn't distinguish between schema1.mytable and schema2.mytable. It was
> suggested that he use aliases instead to make it work.
>
I should subscribe to the -bugs mailing list too!!!! I didn't get
the complete picture there.
I don't think adding a schema_name to EXPLAIN's output, is really
a good idea!! The ALIAS feature of the SQL language caters to this
very need of assigning unambiguous names to tables.
And we should be careful when adding any special code for EXPLAIN
[ ANALYZE ]. For an example what would happen if we do that, consider
this:
If a big JOIN query takes N minutes on MS SQL Server, and I wish
to see the plan why it is taking that long, one would expect me to
enable 'Show Execution Plan' in the SQL Query Analyzer (similar to
PG's EXPLAIN ANALYZE). And when I do that, the query now takes more
than 2*N minutes to come back. I assume this extra delay is caused by
the overhead of extra processing it does at row-source level (like how
many rows passed through this row-source, average row-size, etc.).