From: | Bob Lunney <bob_lunney(at)yahoo(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-bugs(at)postgresql(dot)org |
Subject: | Re: Error while altering an inheritance hierarchy in mid-query |
Date: | 2010-03-19 03:22:14 |
Message-ID: | 633121.66821.qm@web39706.mail.mud.yahoo.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-bugs |
So I did miss something! Thanks for the brilliant explanation and simple solution, Tom.
Bob
--- On Thu, 3/18/10, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> Subject: Re: [BUGS] Error while altering an inheritance hierarchy in mid-query
> To: "Bob Lunney" <bob_lunney(at)yahoo(dot)com>
> Cc: pgsql-bugs(at)postgresql(dot)org
> Date: Thursday, March 18, 2010, 3:26 PM
> Bob Lunney <bob_lunney(at)yahoo(dot)com>
> writes:
> > 1. A select into query is run which summarizes
> the data from a partition into a table outside the
> inheritance hierarchy, which is then indexed.
> > 2. Then
> > a. a transaction is begun,
> > b. the original partition is
> dropped,
> > c. the new table renamed to the
> original partition's name,
> > d. the new table's unique index
> is renamed,
> > e. the appropriate check
> constraint is added,
> > f. select privilege is granted,
> and
> > g. the transaction is
> committed.
>
> I'd suggest taking an exclusive lock on the inheritance
> hierarchy's
> parent table between 2a and 2b. The "could not open
> relation with OID
> nnn" error is to be expected when a table is dropped just
> as a query
> is in the act of trying to open it, which is what could
> happen here if
> a query on the parent table runs concurrently with the
> DROP.
> You're also at risk that a concurrent query might see both
> or neither
> of the old and new versions of the partition, leading to
> bogus answers.
> Both of these things would be fixed if incoming queries are
> blocked
> while trying to open the parent table, rather than while
> iterating
> through the list of inheritance children for it.
>
>
> regards, tom lane
>
From | Date | Subject | |
---|---|---|---|
Next Message | Krishnamoorthy | 2010-03-19 05:30:30 | BUG #5380: error in xlog |
Previous Message | Tom Lane | 2010-03-18 19:26:32 | Re: Error while altering an inheritance hierarchy in mid-query |