Horton

Re: FOR SHARE vs FOR UPDATE locks

Decibel! <decibel@decibel.org>

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From: Jim Nasby <decibel@decibel.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "Heikki Linnakangas" <heikki@enterprisedb.com>, "Alvaro Herrera" <alvherre@commandprompt.com>, "Simon Riggs" <simon@2ndquadrant.com>, pgsql-hackers@postgresql.org, pgsql-core@postgresql.org
Date: 2006-12-04T06:44:01Z
Lists: pgsql-hackers, pgsql-docs 
On Dec 1, 2006, at 10:46 AM, Tom Lane wrote:
> If we
> do make it throw an error I'm afraid that we will break applications
> that aren't having a problem at the moment.

What about throwing a warning? Shouldn't break anything, but at least  
then anyone who's experiencing this and has just gotten lucky so far  
will have a better idea that it's happening.

As for possibly using the in-memory store of multiple CIDs affecting  
a tuple, could that not work if that store contained enough  
information to 'rollback' the lock to it's original state when  
restoring to a savepoint? AFAIK other backends would only need to  
know what the current lock being held was, they wouldn't need to know  
the history of it themselves...
--
Jim Nasby                                            jim@nasby.net
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)