Luigi,
Is the file with the 'directory' a candidate for caching within OrientDB or
is that handled by the OS?
On Thursday, June 11, 2015 at 10:57:42 PM UTC-7, Luigi Dell'Aquila wrote:
>
> Hi guys,
>
> I'd like to shed some light on this "magic" :-)
>
> a RID is made of two numbers (a short and a long, at this stage, but the
> first one will become a long too in next releases, it's in the radmap).
> Say the RID is #xxx:yyy
>
> xxx is the cluster ID, it identifies the cluster where the record is
> stored. OrientDB keeps a 1-1 mapping from this number to a file on the
> filesystem (the cluster file, well, two files actually).
> yyy is the cluster position, it defines the physical position where the
> record is stored in the cluster file.
>
> The cluster is actually made of two files, one is the "directory" of
> cluster positions and the second one contains the actual data.
> The first file contains fixed size records that contain physical pointers
> to positions in the second file.
>
> Now let's do a practical example
>
> #12:20 = {@class="Person", name="Luigi"}
>
> 1) OrientDB translates 12 -> "person" cluster
> 2) person.cpm is the "directory" for that cluster, person.pcl contains data
> 3) say every entry in the directory is N bytes long, OrientDB seeks in
> person.pcm at position N*20 (20 is the cluster position)
> 4) at this position it will find another number, say 12345, this is the
> position of the record content in person.pcl
>
> So to resume you are doing two constant time operations, a direct seek in
> person.cpm and another one in person.pcl
>
> Luigi
>
>
>
>
>
> 2015-06-11 11:59 GMT+02:00 James Wang <[email protected] <javascript:>>:
>
>> agreed
>>
>>
>> On Thursday, 11 June 2015 06:38:06 UTC+1, scott molinari wrote:
>>>
>>> I was wondering, is an index automatically created on the RID? I would
>>> imagine it is, just wanted to be sure.
>>>
>>> Also, are there any plans to create something like a sparse index in
>>> MongoDB? Or does Orient already have this capability?
>>>
>>> Scott
>>>
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