Re: [HACKERS] [PATCHES] extension for sql update
Susanne Ebrecht wrote: > > That's what I was thinking. Glad someone else replied. ;-) > > > If you're looking for votes, +1. I'll gladly take a subset of the > SQL standard UPDATE table SET (...) = (...) over having nothing. > > >>> +1 here, too. :) > >>> > >>> > >> +1 > >> > > > > I am working now to get this into 8.2. > > > > > I am glad to read this. But what does it mean to me? Shall I change the > patch someway? Well, it doesn't apply to CVS HEAD. I assume it was made for 8.1.X. I can adjust it and apply it, or you can make the changes and send in a new version. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 6: explain analyze is your friend
Re: [HACKERS] [PATCHES] extension for sql update
Bruce Momjian wrote: Robert Treat wrote: On Saturday 12 August 2006 16:16, David Fetter wrote: On Fri, Aug 11, 2006 at 05:11:03PM -0500, Jim C. Nasby wrote: On Fri, Aug 11, 2006 at 10:59:45AM -0400, Bruce Momjian wrote: Peter Eisentraut wrote: Bruce Momjian wrote: Are we sure we don't want the patch for a non-subquery version of SET ROW for 8.2? o Allow UPDATE tab SET ROW (col, ...) = (...) for updating multiple columns It seems to be moderately useful as a notational convenience for now. Is it too hard to rip it back out once the full row support arrives? That seems speculation at best anyway. That's what I was thinking. Glad someone else replied. ;-) If you're looking for votes, +1. I'll gladly take a subset of the SQL standard UPDATE table SET (...) = (...) over having nothing. +1 here, too. :) +1 I am working now to get this into 8.2. I am glad to read this. But what does it mean to me? Shall I change the patch someway? Susanne ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] [PATCHES] extension for sql update
Robert Treat wrote: > On Saturday 12 August 2006 16:16, David Fetter wrote: > > On Fri, Aug 11, 2006 at 05:11:03PM -0500, Jim C. Nasby wrote: > > > On Fri, Aug 11, 2006 at 10:59:45AM -0400, Bruce Momjian wrote: > > > > Peter Eisentraut wrote: > > > > > Bruce Momjian wrote: > > > > > > Are we sure we don't want the patch for a non-subquery version of > > > > > > SET ROW for 8.2? > > > > > > > > > > > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating > > > > > > multiple columns > > > > > > > > > > It seems to be moderately useful as a notational convenience for > > > > > now. > > > > > > > > > > Is it too hard to rip it back out once the full row support > > > > > arrives? That seems speculation at best anyway. > > > > > > > > That's what I was thinking. Glad someone else replied. ;-) > > > > > > If you're looking for votes, +1. I'll gladly take a subset of the > > > SQL standard UPDATE table SET (...) = (...) over having nothing. > > > > +1 here, too. :) > > > > +1 I am working now to get this into 8.2. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 6: explain analyze is your friend
Re: [HACKERS] [PATCHES] extension for sql update
On Saturday 12 August 2006 16:16, David Fetter wrote:
> On Fri, Aug 11, 2006 at 05:11:03PM -0500, Jim C. Nasby wrote:
> > On Fri, Aug 11, 2006 at 10:59:45AM -0400, Bruce Momjian wrote:
> > > Peter Eisentraut wrote:
> > > > Bruce Momjian wrote:
> > > > > Are we sure we don't want the patch for a non-subquery version of
> > > > > SET ROW for 8.2?
> > > > >
> > > > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating
> > > > > multiple columns
> > > >
> > > > It seems to be moderately useful as a notational convenience for
> > > > now.
> > > >
> > > > Is it too hard to rip it back out once the full row support
> > > > arrives? That seems speculation at best anyway.
> > >
> > > That's what I was thinking. Glad someone else replied. ;-)
> >
> > If you're looking for votes, +1. I'll gladly take a subset of the
> > SQL standard UPDATE table SET (...) = (...) over having nothing.
>
> +1 here, too. :)
>
+1
--
Robert Treat
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Re: [HACKERS] [PATCHES] extension for sql update
On Fri, Aug 11, 2006 at 05:11:03PM -0500, Jim C. Nasby wrote: > On Fri, Aug 11, 2006 at 10:59:45AM -0400, Bruce Momjian wrote: > > Peter Eisentraut wrote: > > > Bruce Momjian wrote: > > > > Are we sure we don't want the patch for a non-subquery version of SET > > > > ROW for 8.2? > > > > > > > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating > > > > multiple columns > > > > > > It seems to be moderately useful as a notational convenience for > > > now. > > > > > > Is it too hard to rip it back out once the full row support > > > arrives? That seems speculation at best anyway. > > > > That's what I was thinking. Glad someone else replied. ;-) > > If you're looking for votes, +1. I'll gladly take a subset of the > SQL standard UPDATE table SET (...) = (...) over having nothing. +1 here, too. :) Cheers, D -- David Fetter <[EMAIL PROTECTED]> http://fetter.org/ phone: +1 415 235 3778AIM: dfetter666 Skype: davidfetter Remember to vote! ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] [PATCHES] extension for sql update
On Fri, Aug 11, 2006 at 10:59:45AM -0400, Bruce Momjian wrote: > Peter Eisentraut wrote: > > Bruce Momjian wrote: > > > Are we sure we don't want the patch for a non-subquery version of SET > > > ROW for 8.2? > > > > > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating > > > multiple columns > > > > It seems to be moderately useful as a notational convenience for now. > > > > Is it too hard to rip it back out once the full row support arrives? > > That seems speculation at best anyway. > > That's what I was thinking. Glad someone else replied. ;-) If you're looking for votes, +1. I'll gladly take a subset of the SQL standard UPDATE table SET (...) = (...) over having nothing. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.comwork: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] [PATCHES] extension for sql update
Peter Eisentraut wrote: > Bruce Momjian wrote: > > Are we sure we don't want the patch for a non-subquery version of SET > > ROW for 8.2? > > > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating > > multiple columns > > It seems to be moderately useful as a notational convenience for now. > > Is it too hard to rip it back out once the full row support arrives? > That seems speculation at best anyway. That's what I was thinking. Glad someone else replied. ;-) -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] [PATCHES] extension for sql update
Bruce Momjian wrote: > Are we sure we don't want the patch for a non-subquery version of SET > ROW for 8.2? > > o Allow UPDATE tab SET ROW (col, ...) = (...) for updating > multiple columns It seems to be moderately useful as a notational convenience for now. Is it too hard to rip it back out once the full row support arrives? That seems speculation at best anyway. -- Peter Eisentraut http://developer.postgresql.org/~petere/ ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] [PATCHES] extension for sql update
Are we sure we don't want the patch for a non-subquery version of SET ROW for 8.2? o Allow UPDATE tab SET ROW (col, ...) = (...) for updating multiple columns --- Tom Lane wrote: > Peter Eisentraut <[EMAIL PROTECTED]> writes: > > Am Mittwoch, 26. Juli 2006 22:58 schrieb Tom Lane: > >> The reason people want this syntax is that they expect to be > >> able to write, say, > >> UPDATE mytab SET (foo, bar, baz) = > >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > > I don't find any derivation in the standard that would permit this. > > Well, there are two ways to get there. SQL99 does not actually have the > syntax with parentheses on the left, but what it does have is SET ROW: > > ::= > > | > > ::= > > | ROW > | > > > > ::= > > | > > and you can derive (SELECT ...) from via > > ::= > ... > | > > ::= > ... > | > > ::= > ... > | > > ::= > > ::= > > > ::= > [ ] > > ::= > > > ::= > > > ::= > > > ::= > > > ::= > > > ::= > SELECT [ ] > > > Another interesting restriction in SQL99 is > > 9) If an specifies ROW, then: > > a) shall consist of exactly one > SC. > > SQL2003 seems to have dropped the ROW syntax entirely, but instead they > have > >::= > >::= > > >::= > > and from there it goes through just like before. > > regards, tom lane > > ---(end of broadcast)--- > TIP 4: Have you searched our list archives? > >http://archives.postgresql.org -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [HACKERS] [PATCHES] extension for sql update
Peter Eisentraut <[EMAIL PROTECTED]> writes: > Am Mittwoch, 26. Juli 2006 22:58 schrieb Tom Lane: >> The reason people want this syntax is that they expect to be >> able to write, say, >> UPDATE mytab SET (foo, bar, baz) = >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > I don't find any derivation in the standard that would permit this. Well, there are two ways to get there. SQL99 does not actually have the syntax with parentheses on the left, but what it does have is SET ROW: ::= | ::= | ROW | ::= | and you can derive (SELECT ...) from via ::= ... | ::= ... | ::= ... | ::= ::= ::= [ ] ::= ::= ::= ::= ::= ::= SELECT [ ] Another interesting restriction in SQL99 is 9) If an specifies ROW, then: a) shall consist of exactly one SC. SQL2003 seems to have dropped the ROW syntax entirely, but instead they have ::= ::= ::= and from there it goes through just like before. regards, tom lane ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] [PATCHES] extension for sql update
On Sun, Jul 30, 2006 at 08:38:30PM -0400, Rod Taylor wrote: > On Sun, 2006-07-30 at 20:20 -0400, Robert Treat wrote: > > On Thursday 27 July 2006 09:28, Bruce Momjian wrote: > > > Tom Lane wrote: > > > > Bruce Momjian <[EMAIL PROTECTED]> writes: > > > > > Tom Lane wrote: > > > > >> UPDATE mytab SET (foo, bar, baz) = > > > > >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > > > > > > > > > That UPDATE example is interesting because I remember when using > > > > > Informix that I had to do a separate SELECT statement for each UPDATE > > > > > column I wanted to update. I didn't realize that you could group > > > > > columns and assign them from a single select --- clearly that is a > > > > > powerful syntax we should support some day. > > > > > > > > No question. The decision at hand is whether we want to look like > > > > we support it, when we don't yet. I'd vote not, because I think the > > > > main use-case for the row-on-the-left syntax is exactly this, and > > > > so I fear people will just get frustrated if they see it in the > > > > syntax synopsis and try to use it. > > > > > > > I'm not a big fan of implementing partial solutions (remember "left-joins > > are > > not implemented messages" :-) way back when) , however in my experience > > with > > this form of the update command, the primary usage is not to use a > > subselect > > to derive the values, but to make it easier to generate sql, using a single > > I disagree. UPDATE mytab SET (foo, bar, baz) =(SELECT ...) is the > specifications way of doing an update with a join. That is its primary > purpose. > > UPDATE ... FROM is a PostgreSQL alternative to the above. An alternative that people have been using without complaint for years (probably because a number of other databases do the same thing). Perhaps a good compromise would be to allow UPDATE ... (SELECT) where it would meet the current requirements for UPDATE ... FROM. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.comwork: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [HACKERS] [PATCHES] extension for sql update
On Mon, 2006-07-31 at 17:26 +0200, Peter Eisentraut wrote: > Am Mittwoch, 26. Juli 2006 22:58 schrieb Tom Lane: > > The reason people want this syntax is that they expect to be > > able to write, say, > > > > UPDATE mytab SET (foo, bar, baz) = > > (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > I don't find any derivation in the standard that would permit this. The only > thing I could find are variations on > > SET (a) = x -- no parentheses > SET (a, b) = (x, y) > SET (a, b) = ROW (x, y) > > where x and y are some sort of value expression. I would have expected the > sort of thing that you describe, but if you know how to derive that, I'd like > to see it. I believe can be one or more which includes a . gives us the option. For that matter the below portion of gives us: | This breaks down into one or more comma separated s. UPDATE tab SET (...) = ((SELECT foo, bar from a), (select bif,baz from b)); -- ---(end of broadcast)--- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Re: [HACKERS] [PATCHES] extension for sql update
Am Mittwoch, 26. Juli 2006 22:58 schrieb Tom Lane: > The reason people want this syntax is that they expect to be > able to write, say, > > UPDATE mytab SET (foo, bar, baz) = > (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); I don't find any derivation in the standard that would permit this. The only thing I could find are variations on SET (a) = x -- no parentheses SET (a, b) = (x, y) SET (a, b) = ROW (x, y) where x and y are some sort of value expression. I would have expected the sort of thing that you describe, but if you know how to derive that, I'd like to see it. -- Peter Eisentraut http://developer.postgresql.org/~petere/ ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [HACKERS] [PATCHES] extension for sql update
On Sun, 2006-07-30 at 20:20 -0400, Robert Treat wrote: > On Thursday 27 July 2006 09:28, Bruce Momjian wrote: > > Tom Lane wrote: > > > Bruce Momjian <[EMAIL PROTECTED]> writes: > > > > Tom Lane wrote: > > > >> UPDATE mytab SET (foo, bar, baz) = > > > >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > > > > > > > That UPDATE example is interesting because I remember when using > > > > Informix that I had to do a separate SELECT statement for each UPDATE > > > > column I wanted to update. I didn't realize that you could group > > > > columns and assign them from a single select --- clearly that is a > > > > powerful syntax we should support some day. > > > > > > No question. The decision at hand is whether we want to look like > > > we support it, when we don't yet. I'd vote not, because I think the > > > main use-case for the row-on-the-left syntax is exactly this, and > > > so I fear people will just get frustrated if they see it in the > > > syntax synopsis and try to use it. > > > > I'm not a big fan of implementing partial solutions (remember "left-joins are > not implemented messages" :-) way back when) , however in my experience with > this form of the update command, the primary usage is not to use a subselect > to derive the values, but to make it easier to generate sql, using a single I disagree. UPDATE mytab SET (foo, bar, baz) =(SELECT ...) is the specifications way of doing an update with a join. That is its primary purpose. UPDATE ... FROM is a PostgreSQL alternative to the above. -- ---(end of broadcast)--- TIP 6: explain analyze is your friend
Re: [HACKERS] [PATCHES] extension for sql update
On Thursday 27 July 2006 09:28, Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <[EMAIL PROTECTED]> writes:
> > > Tom Lane wrote:
> > >> UPDATE mytab SET (foo, bar, baz) =
> > >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key);
> > >
> > > That UPDATE example is interesting because I remember when using
> > > Informix that I had to do a separate SELECT statement for each UPDATE
> > > column I wanted to update. I didn't realize that you could group
> > > columns and assign them from a single select --- clearly that is a
> > > powerful syntax we should support some day.
> >
> > No question. The decision at hand is whether we want to look like
> > we support it, when we don't yet. I'd vote not, because I think the
> > main use-case for the row-on-the-left syntax is exactly this, and
> > so I fear people will just get frustrated if they see it in the
> > syntax synopsis and try to use it.
>
I'm not a big fan of implementing partial solutions (remember "left-joins are
not implemented messages" :-) way back when) , however in my experience with
this form of the update command, the primary usage is not to use a subselect
to derive the values, but to make it easier to generate sql, using a single
update statement, based on an array of passed in values (in languages like
perl/php/etc...). This solution would solve that problem for us, so I would
lean toward including it. I would be interested in hearing from actual users
who really need the subselect version though, but right now my thinking is
that group is a small minority of who would benefit from this version of the
update command.
--
Robert Treat
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Re: [HACKERS] [PATCHES] extension for sql update
Am Donnerstag, den 27.07.2006, 08:30 -0400 schrieb Tom Lane: > Susanne Ebrecht <[EMAIL PROTECTED]> writes: > > ... We could provide the mixed update syntax and leave the > > typed row value expression for the next release. Do you agree? > > I don't really see the point --- the patch won't provide any new > functionality in anything like its current form, because you can > always just write the separate expressions in the simple one to > one way. If we do offer the row-on-the-left syntax then people > will try to put sub-selects on the right, and won't get anything > beyond an unhelpful "syntax error" message. So my vote would be > to leave it alone until we have a more complete implementation. Look at my intention, why I wrote this patch: In recent years I migrated many customers applications from oracle or informix to postgresql. Every time it was a very painful and annoying job to grep through the code of functions and the whole software, to find all updates and change them manually. Far ago at university, I learned both syntax as standard syntax. Example: set a=1, b=2, c=3 and set (a,b,c)=(1,2,3) I admit, I prefered the second form, too, when I only used informix and it seems also my customers do so. Still now, I never found this syntax with select statement. I am not sure if this is possible with informix or oracle. regards Susanne > > regards, tom lane signature.asc Description: This is a digitally signed message part
Re: [HACKERS] [PATCHES] extension for sql update
Jim Nasby wrote: > On Jul 27, 2006, at 7:30 AM, Tom Lane wrote: > > Susanne Ebrecht <[EMAIL PROTECTED]> writes: > >> ... We could provide the mixed update syntax and leave the > >> typed row value expression for the next release. Do you agree? > > > > I don't really see the point --- the patch won't provide any new > > functionality in anything like its current form, because you can > > always just write the separate expressions in the simple one to > > one way. If we do offer the row-on-the-left syntax then people > > will try to put sub-selects on the right, and won't get anything > > beyond an unhelpful "syntax error" message. So my vote would be > > to leave it alone until we have a more complete implementation. > > While the patch doesn't provide any new functionality, I would still > welcome it simply because I find it a lot easier and cleaner to group > fields together when updating multiple fields at once. > > Even if we would have to rip this patch back out in order to fully > support the spec, we've got a (mostly) working patch right now, and > it sounds like it would take minimal effort to finish it. > > In any case, it sounds like there should be a TODO item out of this. We already had it on the TODO list, but I didn't realize about the subselect issue. I added a sentence to clarify that: o Allow UPDATE tab SET ROW (col, ...) = (...) for updating multiple columns new-->A subselect can also be used as the value source. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
Re: [HACKERS] [PATCHES] extension for sql update
Tom Lane wrote: Susanne Ebrecht <[EMAIL PROTECTED]> writes: ... We could provide the mixed update syntax and leave the typed row value expression for the next release. Do you agree? I don't really see the point --- the patch won't provide any new functionality in anything like its current form, because you can always just write the separate expressions in the simple one to one way. If we do offer the row-on-the-left syntax then people will try to put sub-selects on the right, and won't get anything beyond an unhelpful "syntax error" message. So my vote would be to leave it alone until we have a more complete implementation. It has the advantage that inserts and updates look more "alike". If your sql statements are generated by code, then that removes the need of a special case for updates. greetings, Florian Pflug ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] [PATCHES] extension for sql update
On Jul 27, 2006, at 7:30 AM, Tom Lane wrote: Susanne Ebrecht <[EMAIL PROTECTED]> writes: ... We could provide the mixed update syntax and leave the typed row value expression for the next release. Do you agree? I don't really see the point --- the patch won't provide any new functionality in anything like its current form, because you can always just write the separate expressions in the simple one to one way. If we do offer the row-on-the-left syntax then people will try to put sub-selects on the right, and won't get anything beyond an unhelpful "syntax error" message. So my vote would be to leave it alone until we have a more complete implementation. While the patch doesn't provide any new functionality, I would still welcome it simply because I find it a lot easier and cleaner to group fields together when updating multiple fields at once. Even if we would have to rip this patch back out in order to fully support the spec, we've got a (mostly) working patch right now, and it sounds like it would take minimal effort to finish it. In any case, it sounds like there should be a TODO item out of this. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.comwork: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] [PATCHES] extension for sql update
Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Tom Lane wrote: > >> UPDATE mytab SET (foo, bar, baz) = > >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > > That UPDATE example is interesting because I remember when using > > Informix that I had to do a separate SELECT statement for each UPDATE > > column I wanted to update. I didn't realize that you could group > > columns and assign them from a single select --- clearly that is a > > powerful syntax we should support some day. > > No question. The decision at hand is whether we want to look like > we support it, when we don't yet. I'd vote not, because I think the > main use-case for the row-on-the-left syntax is exactly this, and > so I fear people will just get frustrated if they see it in the > syntax synopsis and try to use it. Agreed. My guess is that a soluion that allows SELECT to return multiple values is going to be in another area of the code, and will require us to remove this code once that is done. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] [PATCHES] extension for sql update
Bruce Momjian <[EMAIL PROTECTED]> writes: > Tom Lane wrote: >> UPDATE mytab SET (foo, bar, baz) = >> (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > That UPDATE example is interesting because I remember when using > Informix that I had to do a separate SELECT statement for each UPDATE > column I wanted to update. I didn't realize that you could group > columns and assign them from a single select --- clearly that is a > powerful syntax we should support some day. No question. The decision at hand is whether we want to look like we support it, when we don't yet. I'd vote not, because I think the main use-case for the row-on-the-left syntax is exactly this, and so I fear people will just get frustrated if they see it in the syntax synopsis and try to use it. regards, tom lane ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] [PATCHES] extension for sql update
Tom Lane wrote: > much anything that can generate a row. The patch as you have it > provides nothing more than syntactic sugar for something people can do > anyway. The reason people want this syntax is that they expect to be > able to write, say, > > UPDATE mytab SET (foo, bar, baz) = > (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > and with something like that you can't break apart the row-valued > expression in the grammar. So in reality the feature has to propagate > much further into the backend than this. That UPDATE example is interesting because I remember when using Informix that I had to do a separate SELECT statement for each UPDATE column I wanted to update. I didn't realize that you could group columns and assign them from a single select --- clearly that is a powerful syntax we should support some day. -- Bruce Momjian [EMAIL PROTECTED] EnterpriseDBhttp://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] [PATCHES] extension for sql update
Susanne Ebrecht <[EMAIL PROTECTED]> writes: > ... We could provide the mixed update syntax and leave the > typed row value expression for the next release. Do you agree? I don't really see the point --- the patch won't provide any new functionality in anything like its current form, because you can always just write the separate expressions in the simple one to one way. If we do offer the row-on-the-left syntax then people will try to put sub-selects on the right, and won't get anything beyond an unhelpful "syntax error" message. So my vote would be to leave it alone until we have a more complete implementation. regards, tom lane ---(end of broadcast)--- TIP 6: explain analyze is your friend
Re: [HACKERS] [PATCHES] extension for sql update
Am Mittwoch, den 26.07.2006, 16:58 -0400 schrieb Tom Lane: > Susanne Ebrecht <[EMAIL PROTECTED]> writes: > This is a cute hack, but it does only a small part of what I think the > spec says. Thank you for compliment. > > In the first place, the SQL syntax is pretty clear that you can combine > simple and multiple assignment in the same UPDATE: Ups, I asked about mixed syntax and I missunderstood the answer (I thougt there is nothing spezified about mixed syntax). But fixing this, seems not to be difficult. > The patch doesn't do that, but it wouldn't be too hard to fix. The more > serious problem is that > > ::= > > and is supposed to be pretty > much anything that can generate a row. The patch as you have it > provides nothing more than syntactic sugar for something people can do > anyway. The reason people want this syntax is that they expect to be > able to write, say, > > UPDATE mytab SET (foo, bar, baz) = > (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key); > > and with something like that you can't break apart the row-valued > expression in the grammar. So in reality the feature has to propagate > much further into the backend than this. This seems to be difficult and I'm not sure this could be done until feature freeze. We could provide the mixed update syntax and leave the typed row value expression for the next release. Do you agree? regards Susanne Ebrecht signature.asc Description: This is a digitally signed message part
Re: [HACKERS] [PATCHES] extension for sql update
Susanne Ebrecht <[EMAIL PROTECTED]> writes:
> here is a patch that extends update syntax following the sql standard.
> The patch includes sgml documentation, too.
> UPDATE table SET (col1, col2, ...) = (val1, val2, ...),
> (colm, coln, ...) = (valm, valn, ...), ...;
This is a cute hack, but it does only a small part of what I think the
spec says.
In the first place, the SQL syntax is pretty clear that you can combine
simple and multiple assignment in the same UPDATE:
::=
UPDATE
SET
[ WHERE ]
::=
[ { }... ]
::=
|
::=
::=
[ { } ... ]
The patch doesn't do that, but it wouldn't be too hard to fix. The more
serious problem is that
::=
and is supposed to be pretty
much anything that can generate a row. The patch as you have it
provides nothing more than syntactic sugar for something people can do
anyway. The reason people want this syntax is that they expect to be
able to write, say,
UPDATE mytab SET (foo, bar, baz) =
(SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key);
and with something like that you can't break apart the row-valued
expression in the grammar. So in reality the feature has to propagate
much further into the backend than this.
regards, tom lane
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