| From: | Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru> |
|---|---|
| To: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Masahiro Ikeda <ikedamsh(at)oss(dot)nttdata(dot)com>, Tomas Vondra <tomas(at)vondra(dot)me>, Masahiro(dot)Ikeda(at)nttdata(dot)com, pgsql-hackers(at)lists(dot)postgresql(dot)org, Masao(dot)Fujii(at)nttdata(dot)com |
| Subject: | Re: Adding skip scan (including MDAM style range skip scan) to nbtree |
| Date: | 2025-04-01 17:31:59 |
| Message-ID: | 3eab6874-6a68-424b-89dd-44320b7e7858@postgrespro.ru |
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| Lists: | pgsql-hackers |
On 01.04.2025 17:39, Matthias van de Meent wrote:
> On Fri, 28 Mar 2025 at 22:59, Peter Geoghegan<pg(at)bowt(dot)ie> wrote:
>> On Tue, Mar 25, 2025 at 7:45 PM Peter Geoghegan<pg(at)bowt(dot)ie> wrote:
>>> Attached is v31, which has a much-improved _bt_skip_ikeyprefix (which
>>> I've once again renamed, this time to _bt_set_startikey).
>> Attached is v32
>> +static bool _bt_s**parray_shrink
> I'd like to understand the "shrink" here, as it's not entirely clear to me.
> The functions are exclusively called through dispatch in
> _bt_compare_array_scankey_args, and I'd expected that naming to be
> extended to these functions.
I understood _bt_skiparray_shrink() as the function that refines the
range of values that a skip array will consider,
by interpreting existing scalar inequality conditions and applying them
to limit the bounds of the skip scan.
I understood "shrink" to mean narrowing the range of values that the
skip array will consider during the index scan.
--
Regards,
Alena Rybakina
Postgres Professional
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