RE: Better performance no-throw conversion?

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От ldh@laurent-hasson.com
Тема RE: Better performance no-throw conversion?
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Msg-id MN2PR15MB256014B342D711821FE0515E85D49@MN2PR15MB2560.namprd15.prod.outlook.com
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Ответ на Re: Better performance no-throw conversion?  (Andrew Dunstan <andrew@dunslane.net>)
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   >  -----Original Message-----
   >  From: Andrew Dunstan <andrew@dunslane.net>
   >  Sent: Wednesday, September 8, 2021 13:31
   >  To: ldh@laurent-hasson.com; pgsql-performance@postgresql.org
   >  Subject: Re: Better performance no-throw conversion?
   >
   >
   >  On 9/8/21 1:17 PM, ldh@laurent-hasson.com wrote:
   >  >
   >  > Hello,
   >  >
   >  >
   >  >
   >  > Some databases such as SQLServer (try_cast) or BigQuery (safe.cast)
   >  > offer not-throw conversion. In general, these tend to perform better
   >  > than custom UDFs that catch exceptions and are also simpler to use.
   >  > For example, in Postgres, I have a function that does the following:
   >  >
   >  >
   >  >
   >  > CREATE OR REPLACE FUNCTION toFloat(str varchar, val real)
   >  >
   >  > RETURNS real AS $$
   >  >
   >  > BEGIN
   >  >
   >  >   RETURN case when str is null then val else str::real end;
   >  >
   >  > EXCEPTION WHEN OTHERS THEN
   >  >
   >  >   RETURN val;
   >  >
   >  > END;
   >  >
   >  > $$ LANGUAGE plpgsql COST 1 IMMUTABLE;
   >  >
   >  >
   >  >
   >  > I couldn't find a reference to such capabilities in Postgres and
   >  > wondered if I missed it, and if not, is there any plan to add such a
   >  > feature?
   >  >
   >  >
   >  >
   >
   >
   >  Not that I know of, but you could probably do this fairly simply in C.
   >
   >
   >  cheers
   >
   >
   >  andrew
   >
   >  --
   >  Andrew Dunstan
   >  EDB: https://www.enterprisedb.com


Hello Andrew,

I work across multiple platforms (windows, linux, multiple managed cloud versions...) and a C-based solution would be
problematicfor us. 

Thank you,
Laurent.






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