|From:||Jan Wieck <jan(at)wi3ck(dot)info>|
|To:||Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>|
|Cc:||Kevin Grittner <kgrittn(at)postgresql(dot)org>, pgsql-hackers(at)postgresql(dot)org|
|Subject:||Re: [COMMITTERS] pgsql: Fix an O(N^2) problem in foreign key references.|
|Views:||Raw Message | Whole Thread | Download mbox | Resend email|
On 09/18/2015 10:47 AM, Tom Lane wrote:
> Jan Wieck <jan(at)wi3ck(dot)info> writes:
>> Attached is a complete rework of the fix from scratch, based on Tom's
>> The code now maintains a double linked list as suggested, but only uses
>> it to mark all currently valid entries as invalid when hashvalue == 0.
>> If a specific entry is invalidated it performs a hash lookup for maximum
>> efficiency in that case.
> That does not work; you're ignoring the possibility of hashvalue
> collisions, and for that matter not considering that the hash value
> is not equal to the hash key. I don't think your code is invalidating
> the right entry at all during a foreign key constraint update, and
> it certainly cannot do the right thing if there's a hash value collision.
> Attached is something closer to what I was envisioning; can you do
> performance testing on it?
Sorry for the delay.
Yes, that patch also has the desired performance for restoring a schema
with hundreds of thousands of foreign key constraints.
Senior Software Engineer
|Next Message||Tom Lane||2015-09-25 16:21:10||pgsql: Further fix for psql's code for locale-aware formatting of numer|
|Previous Message||Tom Lane||2015-09-25 04:01:33||pgsql: Further fix for psql's code for locale-aware formatting of numer|
|Next Message||Tom Lane||2015-09-25 14:49:35||Re: cluster_name and update_process_title documentation|
|Previous Message||Teodor Sigaev||2015-09-25 14:11:33||Re: WIP: Rework access method interface|