Thread

1. NULLs in array_cat vs array || array

   Thom Brown <thom@linux.com> — 2011-02-15T21:37:21Z

   Hi all,
   
   I assumed array_cat would behave similarly to array || array, but it
   appears not when it comes to NULLs.  Shouldn't these have identical
   functionality?  The attached patch makes it so, although it would
   break existing code.
   
   Would such a change have any knock-on effect, or cause inconsistency
   with other functions?
   
   Thanks
   
   Thom
   
   -- 
   Thom Brown
   Twitter: @darkixion
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2. Re: NULLs in array_cat vs array || array

   Cédric Villemain <cedric.villemain.debian@gmail.com> — 2011-02-15T21:46:09Z

   2011/2/15 Thom Brown <thom@linux.com>:
   > Hi all,
   >
   > I assumed array_cat would behave similarly to array || array, but it
   > appears not when it comes to NULLs.  Shouldn't these have identical
   > functionality?  The attached patch makes it so, although it would
   > break existing code.
   
   There is bugreport and todo entry for that if it helps:
   
   http://archives.postgresql.org/pgsql-bugs/2008-11/msg00032.php
   
   
   >
   > Would such a change have any knock-on effect, or cause inconsistency
   > with other functions?
   >
   > Thanks
   >
   > Thom
   >
   > --
   > Thom Brown
   > Twitter: @darkixion
   > IRC (freenode): dark_ixion
   > Registered Linux user: #516935
   >
   >
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   >
   
   
   
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   Cédric Villemain               2ndQuadrant
   http://2ndQuadrant.fr/     PostgreSQL : Expertise, Formation et Support
   
   

3. Re: NULLs in array_cat vs array || array

   Tom Lane <tgl@sss.pgh.pa.us> — 2011-02-15T21:47:42Z

   Thom Brown <thom@linux.com> writes:
   > I assumed array_cat would behave similarly to array || array, but it
   > appears not when it comes to NULLs.  Shouldn't these have identical
   > functionality?  The attached patch makes it so, although it would
   > break existing code.
   
   That patch is the hard way: the right change would be to remove the code
   altogether and mark the function strict in pg_proc.  However, the fact
   that it's not like that already shows that we went out of our way to
   make it so.  I don't think we should undo that decision just because
   somebody submits a patch to do so.
   
   Also, so far as I can see array_cat *is* ||, so I'm not sure what
   discrepancy in behavior you're on about.
   
   			regards, tom lane
   
   

4. Re: NULLs in array_cat vs array || array

   Thom Brown <thom@linux.com> — 2011-02-15T21:50:00Z

   On 15 February 2011 21:46, Cédric Villemain
   <cedric.villemain.debian@gmail.com> wrote:
   > 2011/2/15 Thom Brown <thom@linux.com>:
   >> Hi all,
   >>
   >> I assumed array_cat would behave similarly to array || array, but it
   >> appears not when it comes to NULLs.  Shouldn't these have identical
   >> functionality?  The attached patch makes it so, although it would
   >> break existing code.
   >
   > There is bugreport and todo entry for that if it helps:
   >
   > http://archives.postgresql.org/pgsql-bugs/2008-11/msg00032.php
   
   Ah, I see.  More to it than meets the eye.  My bad.
   
   -- 
   Thom Brown
   Twitter: @darkixion
   IRC (freenode): dark_ixion
   Registered Linux user: #516935
   
   

5. Re: NULLs in array_cat vs array || array

   Thom Brown <thom@linux.com> — 2011-02-15T21:58:20Z

   On 15 February 2011 21:47, Tom Lane <tgl@sss.pgh.pa.us> wrote:
   > Also, so far as I can see array_cat *is* ||, so I'm not sure what
   > discrepancy in behavior you're on about.
   
   You've confused me now.  I had a case where I replaced || with , and
   surrounded it with array_cat, and the result differed, and now I can't
   recreate it.  I think I should get an early night.
   
   -- 
   Thom Brown
   Twitter: @darkixion
   IRC (freenode): dark_ixion
   Registered Linux user: #516935