Re: [WIP] [B-Tree] Retail IndexTuple deletion

15.08.2018 12:17, Masahiko Sawada пишет:
> On Tue, Aug 7, 2018 at 4:19 PM, Andrey Lepikhov
> <a(dot)lepikhov(at)postgrespro(dot)ru> wrote:
>> Hi,
>> I wrote a background worker (hcleaner) to demonstrate application of Retail
>> IndexTuple deletion (see patch at attachment).
>
> The patch doesn't seem to have the hcleaner code. Could you share it?

I appreciate you pointing out my mistake.

Attachment contains full patch set: indexTuple retail deletion, ordering
b-tree tuples by tid (provided by Peter Geoghean) and background cleaner.

In this version of background worker you can show state of the hcleaner
at the 'pg_stat_progress_cleaner' view, like VACUUM.

unlike the previous version, hcleaner check presence a block in memory
before cleanup (see RBM_NORMAL_NO_READ mode at ReadBufferExtended()
call) and do not read blocks from a disk storage (only on shutdown after
SIGTERM signal catch).

For feature demonstration you can use simple test (autovacuum = off):
pgbench -i -s 1 && psql -c $"CREATE INDEX pgbench_accounts_ext ON
public.pgbench_accounts USING btree (abalance);" && pgbench -t <n> -c 20
-j 8 -f test.pgb

where test.pgb is:
-------
\set aid random(1, 100000 * :scale)
\set delta random(-5000, 5000)
UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid;
-------

My workstation shows:

| master | patched |
n |HEAP size | INDEX size | HEAP size | INDEX size |
---------------|-------------------------------------|
2e3 | 13 MB | 2.3 MB | 13 MB | 2.3 MB |
2e4 | 14 MB | 2.7 MB | 13 MB | 2.7 MB |
2e5 | 14 MB | 8.0 MB | 14 MB | 4.8 MB |
2e6 | 61 MB | 58. MB | 14 MB | 6.7 MB |

where HEAP size - size of 'pgbench_accounts' relation; INDEX size - size
of 'pgbench_accounts_ext' index relation.
It is demonstrates a relation 'blowing' problem and influence of
hcleaner in an excessive manner.

Some problem is regression tests modification, because hcleaner makes
physical order of tuples in relations unpredictable.

>
> Regards,
>
> --
> Masahiko Sawada
> NIPPON TELEGRAPH AND TELEPHONE CORPORATION
> NTT Open Source Software Center
>

--
Andrey Lepikhov
Postgres Professional
https://postgrespro.com
The Russian Postgres Company