the jokes for pg concurrency write performance

From: wyx6fox(at)sina(dot)com
To: pgsql-performance(at)postgresql(dot)org
Subject: the jokes for pg concurrency write performance
Date: 2010-02-02 04:57:01
Message-ID: 20100202045701.93A404B1C73@mail175-236.sinamail.sina.com.cn
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

hi, first, thanks u for make so good opensource db .

recently maybe half an years ago ,i begin to use pg in a big project for insurance project, belong as the project go on ,and
i found some performance problem on concurrency write situation , then i do a research on concurrency write strategy on postgresql ,

i found a joke ,maybe this joke concurrency strategy is the designer's pround idea, but i think it is a joke , next let me describe the problems:

* joke 1: insert operation would use a excluse lock on reference row by the foreign key . a big big big performance killer , i think this is a stupid design .

* joke 2: concurrency update on same row would lead to that other transaction must wait the earlier transaction complete , this would kill the concurrency performance in some long time transaction situation . a stupid design to ,

this joke design's reason is avoid confliction on read committed isolation , such as this situation:
UPDATE webpages SET hits = hits + 1 WHERE url ='some url ';
when concurrency write transaction on read committed isolation , the hits may result wrong .

this joke design would do seriable write , but i think any stupid developer would not write this code like this stupid sample code , a good code is
use a exclusive lock to do a seriable write on this same row , but the joker think he should help us to do this , i say ,u should no kill concurrency performance and help i do this fucking stupid sample code , i would use a select .. for update to do this :

select 1 from lock_table where lockId='lock1' for update ;
UPDATE webpages SET hits = hits + 1 WHERE url ='some url ';

* joke 3: update 100000 rows on a table no any index , it cost 5-8 seconds , this is not acceptable in some bulk update situation .

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Kevin Grittner 2010-02-02 05:06:55 Re: use pgsql in a big project, but i found pg has some big problem on concurrency write operation, maybe a joke for myself !
Previous Message wyx6fox 2010-02-02 04:39:59 use pgsql in a big project, but i found pg has some big problem on concurrency write operation, maybe a joke for myself !