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RE: Browse() vs read() performance in Odoo 8

by
hans.yonathan
- 11/06/2014 03:09:31

Hi Fabien,

 

Wow, I just know that browse is better than read,

Actually because I read developer memento (there’s a note that read method is faster that browse), so I always assume that read is faster.

But in practice, I always use browse because it easier to code, and I don’t find any different of performance for it.

 

How about the note that we must avoid use browse method inside looping?

 

 

Thank You.

 

Best Regards,

Hans Yonathan

Odoo Support

FALINWA Limited

Expert in Finance, Information System & Business Intelligence

Odoo Silver Partner

Website: www.falinwa.com

Tel. 13670137019 (China - Shenzhen)

 

From: Fabien Pinckaers [mailto:fp@odoo.com]
Sent: Thursday, November 06, 2014 4:02 PM
To: Community: Framework
Subject: Re: Browse() vs read() performance in Odoo 8

 

Hello,

 

Using read() is a bad practice. read() is used for web-services calls

but in your own method calls you should always use browse(). Not only,

it allows s a better quality of the code, but it's also better for the

performance.

 

- read() calls name_get for many2one fields producing extra SQL queries

  you probably don't need.

- browse() is optimized for prefetching and auto-load of fields.

 

It's true that browse() may load a few fields you do not need (not all).

It prefetches stored fields, because those fields do not costs anything

to load in terms of performance.

 

It's very complex to optimize for performance with read() when the code

is complex (involves loops, other method calls). Whereas, with browse(),

the framework do the optimization job for you.

 

Usually, code implemented with read are often with complexities of O(n)

or O(n²) as soon as there is loops in your methods. But codes written

with browse() are automatically O(1) if browse is called at the

beginning of your computations. (not inside loops)

 

Want a small example? Try this code on res.partner:

 

  for company in self.browse(cr, uid, ids, context=context):

    for people in company.child_ids:

      print company.name, people.country_id.code

 

The above will do 6 SQL queries, whatever the length of ids and number

of people/countries. (if IDS>200, he will split into subqueries)

 

The same code with read(), you will probably end up with 3*len(ids) + 3

queries.

 

 

Long story short: browse() scale, read() not. (even in v7 or preceding

versions)

 

 

On 11/05/2014 11:39 PM, Nicolas SCHMITT wrote:

> Hi all.

> 

> When developing with the API 7, I always prefer the read() instead of

> the browse() method.

> Indeed it seems that a browse fetches all the fields in the table,

> whereas the read fetches only the few it needs (that are passed to

> them), thus resulting in a much faster speed.

> 

> Actually I never really liked it, because it is easier/more intuitive to

> use the browse, and the code is nicer.

> 

> So what about performance issues in Odoo8?

> Is it still recommended to prefer the read() in the API 8?

> 

> It would be a shame, moreover now because the browse() in the new API

> seems so much easier to use.

> 

> Thanks for your hints,

> Cordially,

> Nicolas

> 

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-- 

Fabien Pinckaers

Odoo Founder

 

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