Re: [HACKERS] Regarding B-Tree Lookup

Michael Paquier <michael.paquier@gmail.com> writes:
> On Tue, May 2, 2017 at 6:12 PM, Mahi Gurram <teckymahi@gmail.com> wrote:
>> Please suggest me the easiest way to lookup into PK's B-Tree index for
>> getting TIDs.

> Why don't you just use SPI within your extension? No need to copy the
> logic for btree lookups this way.

There's not actually that much code needed, though -- basically
index_beginscan, index_rescan, index_getnext, index_endscan.  One possible
model to follow is systable_beginscan and friends, in genam.c.

I think that you could possibly get away with just applying
systable_beginscan to random user tables, even.  But it's at least a
conceptual mismatch, and there are some things in there, like the
test on IgnoreSystemIndexes, that you probably don't want.
        regards, tom lane