Re: [QUESTIONS] How fully will subselects be implemented?
First, this list is not right place to ask about 6.3 features :)
2nd, subselects within UPDATE are supported.
They are? I thought he wanted to do:
update test set x = (select y from taby)
I didn't think we supported that. Can you confirm that?
3rd, there will be separate select (better say - separate re-scan of
subquery' plan) for each parent row (I assume that you talk about
correlated subqueries) but this will be more efficient than using
SQL-funcs which do _initialization_, scannig, _closing_ of query' plan
for each parent row. When using subqueries performance will be
near the same as for performing Nestloop join.
Good.
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Bruce Momjian | 830 Blythe Avenue
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Reply to msg id not found: 34F3F25B.9C239AEA@sable.krasnoyarsk.su
Herouth Maoz wrote:
I'm developing a new app, and I constantly run into the need of updating
things by data in related columns.Since UPDATE doesn't syntatctically support joins, this means that
subselects in UPDATE are a real must.
OK, now I see he only wants the subquery in the where clause. That
clearly does work.
--
Bruce Momjian | 830 Blythe Avenue
maillist@candle.pha.pa.us | Drexel Hill, Pennsylvania 19026
+ If your life is a hard drive, | (610) 353-9879(w)
+ Christ can be your backup. | (610) 853-3000(h)Import Notes
Reply to msg id not found: 34F3F25B.9C239AEA@sable.krasnoyarsk.su | Resolved by subject fallback
Bruce Momjian wrote:
First, this list is not right place to ask about 6.3 features :)
2nd, subselects within UPDATE are supported.They are? I thought he wanted to do:
update test set x = (select y from taby)
I didn't think we supported that. Can you confirm that?
Oh, this is not supported, sorry.
And select a, (select b from tab2) from tab1 and so on...
Vadim