From: | Markus Wanner <markus(at)bluegap(dot)ch> |
---|---|
To: | PostgreSQL-development Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Index scan troubles |
Date: | 2008-09-02 16:09:17 |
Message-ID: | 48BD652D.9060303@bluegap.ch |
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Thread: | |
Lists: | pgsql-hackers |
Hi,
I'm having a hard time using an index scan. So far, I've done quite well
with ScanKeyInit for equality searches. But now I need to scan an index
from a given starting point. Something like:
(x, y, z,...) > (const, const, const,...)
For the equality operatior, I've used get_sort_group_operators() in
combination with get_opcode() to pass that on as the sk_func of the scan
key. I slowly begin to doubt if that's correct at all.
While it works for equality scans, it does somehow not work for for
BTGreaterStrategy. What am I missing?
I do have the following: an indexStruct on the index (primary key) I
want to use, a TupleDescriptor for the relation I want tuples from and
of course the list of constants (datums) to compare against. I want to
do an index scan to retrieve tuples from that given lower bound upwards
(or forwards).
I don't quite grok all the opfamily and opclass things, yet. Hints and
pointers on where to read on greatly appreciated. A virtual beer for
sample code. ;-)
Regards
Markus Wanner
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