Re: [HACKERS] Solution for LIMIT cost estimation
От | Karl DeBisschop |
---|---|
Тема | Re: [HACKERS] Solution for LIMIT cost estimation |
Дата | |
Msg-id | 200002141451.JAA28380@skillet.infoplease.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] Solution for LIMIT cost estimation (Peter Eisentraut <peter_e@gmx.net>) |
Список | pgsql-hackers |
>> 4. Fascist variant of #3: make LIMIT without ORDER BY be an error. > >Got my vote for that. At least make it a notice: "NOTICE: LIMIT without >ORDER BY results in random data being returned" -- That'll teach 'em. ;) Given the nature of SQL, how could it be otherwise. Select is defined to be unordered. This seems to advocate building a generic SQL tutorial into postgreSQL. I for one would very much rather not have that notice. My reasoning is thus: Say I need a quick shell script to verify that a table has been loaded with reasonable values as part of a cron procedure. One way to do the might be to make a shell script: #!/bin/sh if ! psql feature -tc "select * from elm limit 1" | egrep "^ +[0-9]+|" >/dev/null; then echo no data loaded; fi Thus, I cron this and get email if there is no record returned. AFAICT, this is what should happen. But if you start adding wornings to this perfectly valid query, which will presumedly come out on STDERR, I will get email from this, even though the query and its returns were valid and expected. And I don't want to direct stderr to /dev/null because I do want to be warned if there really is an error. Just my $0.02 worth. -- Karl DeBisschop <kdebisschop@alert.infoplease.com> 617.832.0332 (Fax: 617.956.2696) Information Please - your source for FREE online reference http://www.infoplease.com - Your Ultimate Fact Finder http://kids.infoplease.com - The Great Homework Helper Netsaint Plugins Development http://netsaintplug.sourceforge.net
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