Thread

Re: Patch: add GiST support for BOX @> POINT queries

Andrew Tipton <andrew.t.tipton@gmail.com> — 2011-06-17T10:43:47Z

On Fri, Jun 10, 2011 at 22:16, Hitoshi Harada <umi.tanuki@gmail.com> wrote:
>
> I reviewed the patch and worried about hard-wired magic number as
> StrategyNumber. At least you should use #define to indicate the
> number's meaning.
>
> In addition, the modified gist_box_consistent() is too dangerous;
> q_box is declared in the if block locally and is referenced, which
> pointer is passed to the outer process of the block. AFAIK if the
> local memory of each block is alive outside if block is
> platform-dependent.
>
> Isn't it worth adding new consistent function for those purposes? The
> approach in the patch as stands looks kludge to me.

Thanks for your review.  Coming back to this patch after a few months'
time, I have to say it looks pretty hackish to my eyes as well. :)

I've attempted to add a new consistent function,
gist_boxpoint_consistent(), but the GiST subsystem doesn't call it --
it continues to call gist_box_consistent().  My very simple testcase
is:

CREATE TABLE test (key TEXT PRIMARY KEY, boundary BOX NOT NULL);
CREATE INDEX ON test USING gist (boundary);
INSERT INTO test VALUES ('a', '(2,2,5,5)'), ('b', '(4,4,8,8)'), ('c',
'(7,7,11,11)');
SELECT * FROM test WHERE boundary @> '(4,4)'::POINT;

Prior to my patch, this query is executed as a straightforward seqscan.

Once I add a new strategy to pg_amop.h:
+ DATA(insert ( 2593   603 600 7 s  433 783 0 ));

(603 is the BOX oid, 600 is the POINT oid, and 433 is the @> operator oid):
...the plan switches to an index scan and gist_box_consistent() is
called;  at this point, the query fails to return the correct results.

But even after adding the new consistent proc to pg_proc.h:
+ DATA(insert OID = 8000 (  gist_boxpoint_consistent    PGNSP PGUID 12
1 0 0 f f f t f i 5 0 16 "2281 600 23 26 2281" _null_ _null_ _null_
_null_   gist_boxpoint_consistent _null_ _null_ _null_ ));

And adding it as a new support function in pg_amproc.h:
+ DATA(insert ( 2593   603 600 1 8000 ));
+ DATA(insert ( 2593   603 600 2 2583 ));
+ DATA(insert ( 2593   603 600 3 2579 ));
+ DATA(insert ( 2593   603 600 4 2580 ));
+ DATA(insert ( 2593   603 600 5 2581 ));
+ DATA(insert ( 2593   603 600 6 2582 ));
+ DATA(insert ( 2593   603 600 7 2584 ));

...my gist_boxpoint_consistent() function still doesn't get called.

At this point I'm a bit lost -- while pg_amop.h has plenty of examples
of crosstype comparison operators for btree index methods, there are
none for GiST.  Is GiST somehow a special case in this regard?

-Andrew