Re: Re: LMDB usage on windows - to much memory needed

[Frank Offermanns <Frank.Offermanns@caseris.de>]

Hi,

thanks for the information, but unfortunately
this information is not helpfull for me. 

Is there a way to configure LMDB on
Windows 32 bit, so that a database can be larger?
Or is it mandantory to use 64 bit with
lmdb (at least on windows file systems) when handling larger data?

Regards,
Frank




Von:      
 Kristoffer Sjögren
<stoffe@gmail.com>
An:      
 Frank Offermanns <Frank.Offermanns@caseris.de>,

Kopie:      
 openldap-technical@openldap.org
Datum:      
 28.01.2015 16:32
Betreff:    
   Re: LMDB usage
on windows - to much memory needed

---

Regarding size.

"If an application specifies a size for the file
mapping object that is larger than the size of the actual named file on
disk and if the page protection allows write access (that is, the flProtect
parameter specifies PAGE_READWRITE or PAGE_EXECUTE_READWRITE), then the
file on disk is increased to match the specified size of the file mapping
object. If the file is extended, the contents of the file between the old
end of the file and the new end of the file are not guaranteed to be zero;
the behavior is defined by the file system. If the file on disk cannot
be increased, CreateFileMapping fails and GetLastError returns ERROR_DISK_FULL."

http://msdn.microsoft.com/en-us/library/windows/desktop/aa366537%28v=vs.85%29.aspx

On Wed, Jan 28, 2015 at 3:27 PM, Frank Offermanns <Frank.Offermanns@caseris.de>
wrote:
Hello, 

we would like to change our backend from hdb to mdb.

I did some initial tests and found out the following:
When setting maxsize to 1.4 GB, the size of the database on the file system
is about 1.4 GB. I thought I read that the maxsize has nothing to do with
the actual physical size needed. (If I have only 10 MB of data my database
should be about 10 MB). 
Even worse is the fact, that slapd.exe then needs about 1.5 GB virtual
size memory. 
And if I use 32 Bit slapd.exe the process will crash when reaching 2 GB
virtual size. (as every 32 bit process will do) 

Now my conclusion is, that the things described in the mdb paper are only
valid for unix/linux, because windows uses another memory system. Is this
correct? Or is there a way I haven't found to configure OpenLDAP on windows
so that it does not need so much RAM. 
The size on the disk does not matter for us, but since we use only 32 bit
slapd.exe the RAM does matter. 

Best regards, 
Frank