Re: Delphi connection ?

[Mark Morgan Lloyd <markMLl(dot)pgsql-general(at)telemetry(dot)co(dot)uk>]

John R Pierce wrote:
> Nico Callewaert wrote:

> > The thing you always hear about ODBC is, that it is very slow ?
> >  
>
>
> ADO is significantly faster than ODBC, so the preferred stack would be  
> delphi -> ado -> postgres ole db -> libpq ->postgres
>
> I believe there exists a delphi->ado wrapper (at least my brief googling 
> popped one up)

Granted that this is a general query issue rather than one specific to 
Delphi/ODBC etc., but the major speed problem that I see is where I have 
a clause approximately like

WHERE now() - datetime <= '24 hours'

repeated several times in a query (e.g. in subselects or views). The 
easiest solution is to replace this with a function returning an 
timestamp which is evaluated once during query execution.

The moral of the story is that even if your queries are wrapped in a 
fancy program generated by something like Delphi, always leave yourself 
a way that you can extract a representative query after any 
parameterisation and do an EXPLAIN to look for inefficiencies.

--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]