[Date Prev][Date Next] [Chronological] [Thread] [Top]

RE: questions about LMDB

Sorry for the wrong mail list , I will  forward this request to technical list


-----Original Message-----
From: Howard Chu [mailto:hyc@symas.com] 
Sent: Thursday, March 19, 2015 11:52 PM
To: Shu, Xinxin; openldap-devel@openldap.org
Subject: Re: questions about LMDB

Shu, Xinxin wrote:
> Several other questions about lmdb
> 1) does lmdb store one key-value pair in a single page? How lmdb organizes these key-value pairs in a single page
> 2)  if size is larger than single page size , how lmdb process this request?

This list is for developers to discuss actual coding issues inside the OpenLDAP code; your questions are too elementary and don't belong here. Use the -technical list for user-oriented questions.
> Any help will be appreciated ? thanks
> Cheers,
> xinxin
> -----Original Message-----
> From: Shu, Xinxin
> Sent: Thursday, March 19, 2015 3:49 PM
> To: openldap-devel@openldap.org
> Cc: Shu, Xinxin
> Subject: questions about LMDB
> Hi list ,
> Recently I read docs about lmdb , there are two sentences
> 1) readers do not block writers
> 2) writers do not block readers
> I can understand 'readers do not block writers' , but cannot understand the second one , can someone help explain , how lmdb achieve 'writers do not block readers',  below is my understandings , please correct me if anything wrong.
>   if the access pattern is write - read, since lmdb only support two version of data ,  when the write has been started but not committed ,  the concurrent read may read stale data since write has not been committed.
> Cheers,
> xinxin

   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/