Re: [HACKERS] WIP aPatch: Pgbench Serialization and deadlock errors

From: Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp>
To: nagata(at)sraoss(dot)co(dot)jp
Cc: coelho(at)cri(dot)ensmp(dot)fr, thomas(dot)munro(at)gmail(dot)com, m(dot)polyakova(at)postgrespro(dot)ru, alvherre(at)2ndquadrant(dot)com, pgsql-hackers(at)postgresql(dot)org, teodor(at)sigaev(dot)ru
Subject: Re: [HACKERS] WIP aPatch: Pgbench Serialization and deadlock errors
Date: 2022-03-20 02:53:13
Message-ID: 20220320.115313.1524242767694522509.t-ishii@sranhm.sra.co.jp
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Hi Yugo,

I tested with serialization error scenario by setting:
default_transaction_isolation = 'repeatable read'
The result was:

$ pgbench -t 10 -c 10 --max-tries=10 test
transaction type: <builtin: TPC-B (sort of)>
scaling factor: 10
query mode: simple
number of clients: 10
number of threads: 1
maximum number of tries: 10
number of transactions per client: 10
number of transactions actually processed: 100/100
number of failed transactions: 0 (0.000%)
number of transactions retried: 35 (35.000%)
total number of retries: 74
latency average = 5.306 ms
initial connection time = 15.575 ms
tps = 1884.516810 (without initial connection time)

I had hard time to understand what those numbers mean:
number of transactions retried: 35 (35.000%)
total number of retries: 74

It seems "total number of retries" matches with the number of ERRORs
reported in PostgreSQL. Good. What I am not sure is "number of
transactions retried". What does this mean?

Best reagards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

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