[HACKERS] array_to_string bug?
Folks,
Here's expected behavior:
davidfet...@postgres=# SELECT array(values(1),(null));
?column?
──
{1,NULL}
(1 row)
The next one is just plain unexpected. Either it's a bug, or it needs
more documentation in the function description in the docs, \df+
output, etc.
davidfet...@postgres=# SELECT array_to_string(array(values(1),(null)),'');
array_to_string
─
1
(1 row)
I would have expected it to come out as NULL.
What say?
Cheers,
David.
--
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Re: [HACKERS] array_to_string bug?
David Fetter da...@fetter.org writes: The next one is just plain unexpected. array_to_string ignores null elements. What do you think it should do with them? regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
On Thu, Nov 12, 2009 at 11:20:26AM -0500, Tom Lane wrote: David Fetter da...@fetter.org writes: The next one is just plain unexpected. array_to_string ignores null elements. What do you think it should do with them? It should concatenate them, i.e. return a NULL if the array includes any NULLs. That, or it should explain that it doesn't do that because there's nothing in the docs that would indicate this behavior. Cheers, David. -- David Fetter da...@fetter.org http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
Tom Lane wrote: David Fetter da...@fetter.org writes: The next one is just plain unexpected. array_to_string ignores null elements. What do you think it should do with them? regards, tom lane This seems somewhat related to the long-running discussion from back in February-April regarding string_to_array with empty input which faded away somewhere around here: http://archives.postgresql.org/pgsql-hackers/2009-04/msg00363.php. At the time the decision was to defer any decision to after 8.4. Perhaps there is a solution which can address both cases - ideally one which would, to the extent practical, allow string_to_array to be the inverse of array_to_string. This could be particularly useful when dealing with clients that don't know how to directly deal with PostgreSQL arrays but which can generally easily deal with strings. Although it might cause a fair amount of backward-compatibility trouble, the string representation could either use NULL to represent a null element as is allowed in other contexts or require that empty-string elements be represented as to differentiate ,, (empty-string element) from ,, (null element). Cheers, Steve
Re: [HACKERS] array_to_string bug?
On Thu, Nov 12, 2009 at 1:28 PM, Steve Crawford scrawf...@pinpointresearch.com wrote: Although it might cause a fair amount of backward-compatibility trouble, the string representation could either use NULL to represent a null element as is allowed in other contexts or require that empty-string elements be represented as to differentiate ,, (empty-string element) from ,, (null element). That would cause a substantial amount of grief to people who might not want that behavior, though. I use these functions for creating human-readable output, not for serialization. Simple, predictable behavior is very important. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
On Thu, Nov 12, 2009 at 01:33:41PM -0500, Robert Haas wrote: On Thu, Nov 12, 2009 at 1:28 PM, Steve Crawford scrawf...@pinpointresearch.com wrote: Although it might cause a fair amount of backward-compatibility trouble, the string representation could either use NULL to represent a null element as is allowed in other contexts or require that empty-string elements be represented as to differentiate ,, (empty-string element) from ,, (null element). That would cause a substantial amount of grief to people who might not want that behavior, though. I use these functions for creating human-readable output, not for serialization. Simple, predictable behavior is very important. My question boils down to, why is this string concatenation different from all other string concatenations? For now, the answer can be, it behaves differently with respect to NULLs, and we just document this. We can later decide whether this behavior should change. Cheers, David. -- David Fetter da...@fetter.org http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
Robert Haas robertmh...@gmail.com writes: On Thu, Nov 12, 2009 at 1:28 PM, Steve Crawford scrawf...@pinpointresearch.com wrote: Although it might cause a fair amount of backward-compatibility trouble, the string representation could either use NULL to represent a null element as is allowed in other contexts or require that empty-string elements be represented as to differentiate ,, (empty-string element) from ,, (null element). That would cause a substantial amount of grief to people who might not want that behavior, though. I use these functions for creating human-readable output, not for serialization. Simple, predictable behavior is very important. I agree --- we don't want to start introducing quoting rules into array_to_string. I think the viable alternatives are the current behavior, or treating a NULL element as if it were an empty string. David's idea that the entire output should go to NULL might be sane from a strict semantics point of view, but it also seems to make the function just about entirely useless in practice. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
On Nov 12, 2009, at 10:46 AM, David Fetter wrote: My question boils down to, why is this string concatenation different from all other string concatenations? Does it have something to do with afikoman? David -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] array_to_string bug?
On Thu, Nov 12, 2009 at 11:46:54AM -0800, David Wheeler wrote: On Nov 12, 2009, at 10:46 AM, David Fetter wrote: My question boils down to, why is this string concatenation different from all other string concatenations? Does it have something to do with afikoman? I was wondering who'd comment on that first ;) Cheers, David. -- David Fetter da...@fetter.org http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
