Обсуждение: AW: The lightbulb just went on...

> what happens to sessions is that it does:
> 
> SELECT session_data, id 
> FROM   sessions
> WHERE  id = ?
> FOR UPDATE
> 
> .... client does some processing ...
> 
> UPDATE sesssions set session_data = ? WHERE id = ?;
> 
> (this is where the error happens)
> 
> I think part of my problem might be that sessions is a view 
> and not a table,

Did you create an on update do instead rule ?

This is currently not done automatically for views,
thus views without additional "create rule"s are select only.

But, I am wondering whether the "for update" places the correct lock ?

Andreas

Zeugswetter Andreas SB <ZeugswetterA@wien.spardat.at> writes:
>> SELECT session_data, id 
>> FROM   sessions
>> WHERE  id = ?
>> FOR UPDATE
>>
>> I think part of my problem might be that sessions is a view 
>> and not a table,

> Did you create an on update do instead rule ?
> This is currently not done automatically for views,
> thus views without additional "create rule"s are select only.
> But, I am wondering whether the "for update" places the correct lock ?

Hmm, good point!  I'm not sure what "select for update" on a view ought
to do, but I am pretty sure that the code will not do anything useful
or sensible for this case...
        regards, tom lane

On Thu, 19 Oct 2000, Tom Lane wrote:

> Zeugswetter Andreas SB <ZeugswetterA@wien.spardat.at> writes:
> >> SELECT session_data, id 
> >> FROM   sessions
> >> WHERE  id = ?
> >> FOR UPDATE
> >>
> >> I think part of my problem might be that sessions is a view 
> >> and not a table,
> 
> > Did you create an on update do instead rule ?

Yes actually :).

But Ive since elimintated the rule and figured out I could get
the equivalent functionality I was getting the the RULE/VIEW by just 
using a simple PL/pgSQL trigger.

Since doing that, the "relation XXXXX modified while in use" errors
have gone away, but I'm still not sure I trust VACUUM ANALYZE enough
to run it on a non-idle production database :).  I want to do more
testing before I get that brave :).

Mike