| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Floris Van Nee <florisvannee(at)optiver(dot)com> |
| Cc: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, James Coleman <jtc331(at)gmail(dot)com>, "jesper(dot)pedersen(at)redhat(dot)com" <jesper(dot)pedersen(at)redhat(dot)com>, Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Subject: | Re: Index Skip Scan |
| Date: | 2019-06-23 01:01:57 |
| Message-ID: | CAH2-WzmRT_0YbHF05axQb2OiTUQiQAkr0Lznntj8X3KADKZ-5g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Jun 22, 2019 at 3:15 PM Floris Van Nee <florisvannee(at)optiver(dot)com> wrote:
> Perhaps a question: when stepping through code in GDB, is there an easy way to pretty print for example the contents on an IndexTuple? I saw there's some tools out there that can pretty print plans, but viewing tuples is more complicated I guess.
Try the attached patch -- it has DEBUG1 traces with the contents of
index tuples from key points during index scans, allowing you to see
what's going on both as a B-Tree is descended, and as a range scan is
performed. It also shows details of the insertion scankey that is set
up within _bt_first(). This hasn't been adopted to the patch at all,
so you'll probably need to do that.
The patch should be considered a very rough hack, for now. It leaks
memory like crazy. But I think that you'll find it helpful.
--
Peter Geoghegan
| Attachment | Content-Type | Size |
|---|---|---|
| 0012-Index-scan-positioning-DEBUG1-instrumentation.patch | application/octet-stream | 19.2 KB |
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