[Loadstone] Database redesign

Ari Moisio arimo at iki.fi
Thu May 8 17:06:52 BST 2008


Hi

  Ok, checkpoints finally found. I also confirmed the arrilval alarms, they 
are for checkpoints, not for the points in the database.


  I have to admit i consider now the whole checkpoint concept even more 
confusing than before.



You can still escape from the Gates of hell: Use Linux!
-- 
mr. M01510


On Thu, 8 May 2008, Shawn Kirkpatrick wrote:

> The show area functions will only work on the database. Try use checkpoints
> and then use exploration mode to find them. The find point function only
> works on the database as well.
>
> On Thu, 8 May 2008, Ari Moisio wrote:
>
>> Hi
>>
>>
>> On Thu, 8 May 2008, Shawn Kirkpatrick wrote:
>>
>>> Your edited checkpoints would have been loaded, activate use checkpoints
>>> only and you'd probably see them. In normal opperation only the database is
>>> scanned for point information. This may have to be tweaked to include
>>> checkpoints that may not exist in the current database.
>>
>>  Still no joy. Chekpoint only does not affect the situation at all. In
>> fact all points are visible in in the show area command. Those whose
>> location i haven't changed are marked checked.
>>
>>  One more weird thing. Due to gps drift i'll hear  occasionally arrival
>> announcements about point that appears not to be checked, it is one of
>> those with changed coordinates.    I cannot tell if the point is the point
>> in the database or the point in the checkpoint list. Auto-announce is btw
>> disabled.
>>
>>> If you use a byte correctly you could have 16 main levels with 16 sublevels.
>>> This would make database query construction kind of difficult thoe if you
>>> want to search for multiple types and subtypes. When it's all said and done
>>> it'll probably have 2 bytes for the type system.
>>
>>  I think this is good enough.
>>
>>> This database redesign is quite a ways off thoe.
>>>
>>> On Thu, 8 May 2008, Ari Moisio wrote:
>>>
>>>>
>>>>
>>>>
>>>> On Thu, 8 May 2008, Shawn Kirkpatrick wrote:
>>>>
>>>>> I think your math is a little off when calculating the odds of duplicate
>>>>> user ids. You'd have to come up with two different strings that'll produce
>>>>> the same crc 16 hash for this to happen.
>>>>
>>>>  There is only 65536 differrent crcs and  iirc the birthday theorem with
>>>> 256 strings the probability for two strings with similar crc-16 will be 50
>>>> %.
>>>>
>>>>
>>>>> When a point is created it gets an id and userid, thest don't change. On
>>>>> import the points are checked to see if they have an existing id and userid
>>>>> and if so the data is updated. If you import out of date data then the
>>>>> point's data will also get set to the out of date value. Not much you can do
>>>>> about that. A last modified field would be an extra 4 bytes per entry and
>>>>> that's just a bit much for the purpose.
>>>>
>>>>  Well... i would sacrifice few bytes for the description field to be
>>>> enable to collect and update data with all three  phones i currently use.
>>>>
>>>>  In  addition it is nice to know how recent any point data is.
>>>>
>>>>> The new checkpoints files contain all a point's information. When
>>>>> checkpoints are loaded the point's id and userid are looked up in the
>>>>> currently loaded database. If found the information from the database is
>>>>> used and if not then the information from the file will be used as is. This
>>>>> is why your experiment didn't work.
>>>>
>>>>  I  changed the id field of nearest checkpoints (the field before the
>>>> comment). Still same behavior.  Points with altered coordinates are not
>>>> checkecd anymore. There is no altered descriptions either. There is no
>>>> duplicate points near each other as one could expect.
>>>>
>>>>> A point typing system may only require one extra byte per entry, you can get
>>>>> 256 values in that.
>>>>
>>>>  with one level of categorization the categories should be broad enough to
>>>> contain  a lot of POIs and services. For example all bars and restaurants,
>>>> all health related, all sports related,  all transport related an so on.
>>>> Othervise searching will  become hit and miss. Look for example
>>>> categorization used in Nokia Maps. It has two levels oand aPOI can belong
>>>> to many categories. This is not possible with one byte.
>>>>
>>>>
>>>>> On Thu, 8 May 2008, Ari Moisio wrote:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> On Wed, 7 May 2008, Shawn Kirkpatrick wrote:
>>>>
>>>> You can still escape from the Gates of hell: Use Linux!
>>>> --
>>>> mr. M01510
>>>>
>>>>
>>>> _______________________________________________
>>>> Loadstone mailing list
>>>> Loadstone at loadstone-gps.com
>>>> http://www.loadstone-gps.com/mailman/listinfo/loadstone
>>>>
>>> _______________________________________________
>>> Loadstone mailing list
>>> Loadstone at loadstone-gps.com
>>> http://www.loadstone-gps.com/mailman/listinfo/loadstone
>>>
>>>
>>
>> You can still escape from the Gates of hell: Use Linux!
>> --
>> mr. M01510
>>
>>
>> _______________________________________________
>> Loadstone mailing list
>> Loadstone at loadstone-gps.com
>> http://www.loadstone-gps.com/mailman/listinfo/loadstone
>>
> _______________________________________________
> Loadstone mailing list
> Loadstone at loadstone-gps.com
> http://www.loadstone-gps.com/mailman/listinfo/loadstone
>
>


More information about the Loadstone mailing list