Re: [HACKERS] Index Only Scan support for cube
On Wed, Sep 20, 2017 at 8:26 AM, Andrey Borodin wrote: > Hi hackers! > > 23 мая 2017 г., в 14:53, Andrew Borodin > написал(а): > > > > Here's a small patch that implements fetch function necessary for > > Index Only Scans that use cube data type. > > Tom Lane have just commited d3a4f89 (Allow no-op GiST support functions to > be omitted) Thanks, Tom! : ) > "Index Only Scan support for cube" patch now is obsolete. I'm working on > another similar patch for contribs to support GiST IOS and remove no-op > support functions. > Good. BTW, some strangeness of g_cube_decompress() catch my eye. It compares results of two evaluations of same expression DatumGetNDBOXP(entry->key). NDBOX *key = DatumGetNDBOXP(entry->key); > if (key != DatumGetNDBOXP(entry->key)) In fact it's correct, because it compares results of two detoasting. If datum isn't toasted then results would be the same. And if data is toasted then results would be two different allocation of detoasted datum. However, we do extra detoasting here. For example, see gbt_var_decompress(). There is no extra detoasting here. GBT_VARKEY *key = (GBT_VARKEY *) PG_DETOAST_DATUM(entry->key); > if (key != (GBT_VARKEY *) DatumGetPointer(entry->key)) -- Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
Re: [HACKERS] Index Only Scan support for cube
Hi hackers! > 23 мая 2017 г., в 14:53, Andrew Borodin написал(а): > > Here's a small patch that implements fetch function necessary for > Index Only Scans that use cube data type. Tom Lane have just commited d3a4f89 (Allow no-op GiST support functions to be omitted) Thanks, Tom! : ) "Index Only Scan support for cube" patch now is obsolete. I'm working on another similar patch for contribs to support GiST IOS and remove no-op support functions. Best regards, Andrey Borodin. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
[HACKERS] Index Only Scan support for cube
Hi, hackers! Here's a small patch that implements fetch function necessary for Index Only Scans that use cube data type. I reuse function g_cube_decompress() instead of creating new function g_cube_fetch(). Essentially, they both have to detoast data. How do you think, is it better to create a shallow copy of g_cube_decompress instead? Any other suggestions on the functionality? This CREATE TABLE SOMECUBES AS SELECT CUBE(X,X+1) C FROM GENERATE_SERIES(1,100) X; CREATE INDEX SOMECUBES_IDX ON SOMECUBES USING GIST(C); SET ENABLE_SEQSCAN = FALSE; EXPLAIN (COSTS OFF ) SELECT C FROM SOMECUBES WHERE C<@CUBE(30,40); now produces Index Only Scan using somecubes_idx on somecubes Index Cond: (c <@ '(30),(40)'::cube) instead of Index Scan using somecubes_idx on somecubes Index Cond: (c <@ '(30),(40)'::cube) Best regards, Andrey Borodin, Octonica. cubefetch.patch Description: Binary data -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
