Yes, but the optimizer doesn't know that.
From: vegivamp@stripped [mailto:vegivamp@stripped] On Behalf Of Johan De Meersman
Sent: Wednesday, March 03, 2010 6:16 AM
To: Zardosht Kasheff
Cc: Jonas Oreland; mysql@stripped
Subject: Re: Re bug#45458
Unless I'm very much mistaken, InnoDB tables always have a clustered index
as their primary key.
On Wed, Mar 3, 2010 at 2:58 PM, Zardosht Kasheff <zardosht@stripped> wrote:
> Hello Jonas,
> Thank you for filing this feature request. Are there plans to add
> support for clustered indexes in MySQL soon? This is something I have
> been researching on and off for a while now. Here are my thoughts.
> It seems that there are two parts to this feature request:
> 1) a new flag that allows the storage engine to report that an index
> is clustered
> 2) changes to the optimizer to properly support clustered keys.
> I like #1. The way that I dealt with it was not as good. I added
> handler::supports_clustered_keys(), and used that function and
> HA_CLUSTERING from my patch to determine if an index is clustered.
> Your method is better.
> As for #2, I do not think it is enough. Here are two other locations
> of code I know that will need to be modified:
> 1) find_shortest_key in sql/sql_select.cc. (This will be an addition
> to MySQL bug #39653)
> 2) get_best_ror_intersect in sql/opt_range.cc. This is for
> index_merge. A patch of what I have done is in the attached file
> 9-index_merge_clustering.txt. This patch was the result of a long
> thread on the internals alias (which you may want to CC for this
> discussion). The link to the thread is
> There may be more places that need to be modified. I think the
> approach to finding out if other places need to be modified is to
> pattern match off of how the optimizer deals with clustered v.
> non-clustered primary keys. It does so by having a function
> handler::primary_key_is_clustered. I think one needs to search the
> optimizer for all instances of this function, see why it is being
> called, and see if it applies to clustered v. non-clustered secondary
> keys as well.
> On Wed, Mar 3, 2010 at 5:57 AM, Jonas Oreland <jonas@stripped> wrote:
> > Hi,
> > I just filed http://bugs.mysql.com/bug.php?id=51687
> > which is very related to your bug#45458.
> > If you would care to look at it and provide feedback,
> > I would appreciate it.
> > /Jonas
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