| From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)mit(dot)edu> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, David Fetter <david(at)fetter(dot)org> |
| Subject: | Re: Review: UNNEST (and other functions) WITH ORDINALITY |
| Date: | 2013-07-29 14:35:03 |
| Message-ID: | 51F67D97.2090109@2ndquadrant.com |
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| Lists: | pgsql-hackers |
On 07/29/2013 08:02 PM, Greg Stark wrote:
>> > Unless LATERAL provides a way to do lock-step iteration through a pair
>> > (or more) of functions I don't think we can get rid of SRFs [in select target lists] yet
> You don't even need lateral. This works fine:
>
> postgres=# select * from generate_series(1,10) with ordinality as
Exactly - that's why the previous paragraph was:
>> As far as I can tell LATERAL won't help with this; you'd need unnest
>> WITH ORDINALITY then a join on the ordinal, or you'd need full support
>> for SQL UNNEST with multiple array arguments.
;-)
I'm interested to see that it might be possible to evaluate multiple
"WITH ORDINALITY" SRFs in FROM together rather than having to perform a
join. That'd make it a much saner replacement for SRFs in the SELECT list.
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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