Other spatial database development (PostGIS)

Fri Jul 8 15:45:24 EDT 2005

The plot thickens:

http://support.esri.com/ 
index.cfm?fa=knowledgebase.techarticles.articleShow&d=16643

P

On Friday, July 8, 2005, at 08:00 AM, Paul Ramsey wrote:

> Read-only OleDB would probably work fine. It would still be some  
> effort to implement. Most people really consider read/write the gold  
> standard they need for ArcMap, which is why I was focussing on it.
>
> Paul
>
>
> On 8-Jul-05, at 6:18 AM, uli mueller wrote:
>
>> Paul, why exactly are the signs not promising? Is
>> it "only" because OLEDB provides read-only access for ArcGIS? I did  
>> not
>> really delve into the article you cited, but what I read sounded like
>> you can use PostGIS WKBs 1:1 with OLEDB for ArcGIS?? Has anybody  
>> successfully implemented read-access from ArcGIS 9 to PG? Would this  
>> be only an ugly or also a never-ending hack?
>>
>> Background: We also have a project where we are constrained to use a  
>> personal geodatabase and would be happy to switch to PostGIS.  
>> Read-only would be sufficient in this case.
>>
>> Uli
>>
>> -- 
>> geOps GeoInformatics
>> D-79100 Freiburg
>>
>> Alex Smith wrote:
>>
>>> I'd like to preface this by acknowledging that my technical  
>>> ineptitude may have been the cause of my unsuccessful attempts to  
>>> write tabular data to external OLEDB databases from ArcGIS.  And I'd  
>>> also like to point out that it's been a while since I tried doing so  
>>> - things may have changed.  But my experiences have lead me to  
>>> believe that ESRI has (or had) carefully implemented ArcGIS in a  
>>> manner that prevents users from writing to external DBMS without   
>>> using ArcSDE.  We do alot of spatial processing that output and  
>>> affects a considerable amount of tabular data that many other rely  
>>> on and edit where necessary.  Because we're already pushing the  
>>> limits of Access, I looked into other options when we started some  
>>> new projects....and an affordable option, such as Postgres or MySQL.  
>>>  Here's what I found
>>>  In the original "Exploring ArcObjects" book, published near the  
>>> release of ArcGIS 8.0, states that OLEDB connections to ArcGIS are  
>>> read only.  Hence, we couldn't directly output data to an external  
>>> table joined to a Access based featureclass.  Sure, we can later use  
>>> ADO to update the 'enterprise' database from the Access geodatabase,  
>>> but that starts to get messy or becomes, to use Paul's words, a  
>>> "moderately ugly hack" (why have the middle-man Geodatabase tables -  
>>> like pgArc had the middle-man shapefiles).  So I tried linking in a  
>>> MySQL table to via ODBC in a geodatabase .mdb file and attempted to  
>>> edit that table (no spatial data) from ArcGIS - I got a message  
>>> stating that linked tables cannot be written to.  DAO tables (and  
>>> I'm fairly certain that ArcGIS interacts with Access databases using  
>>> DAO), have a property that returns true if they are linked tables.    
>>> So it seems that the ArcGIS has code that tests this property and  
>>> does not allow users to edit these tables.  I fi
>>>
>> nd it very
>>
>>>  hard to believe that this was accidental.  And I later felt naive  
>>> for thinking I could somehow 'outsmart' them - ESRI's software  
>>> engineers are not dumb.  Expect some resistance in attempting to  
>>> circumnavigate their systems.   I understand their need to protect  
>>> their investment - the ArcGIS spatial editting tools (including  
>>> topology and networks) and ArcSDE must have cost a lot of money to  
>>> develop.  And it's good software - ESRI has earned a lot of its  
>>> success.  It just sucks for those of us on a limited budget - SDE  
>>> licenses on top of commercial RDBMS fees is simply unaffordable in  
>>> our case.   On the other hand, ESRI seems to be opening up.  But  
>>> they must continue to recover their development costs somehow.  And  
>>> I'd be surprised if they'd make it easy for other develop tools to  
>>> compete with their systems.  Yes, being able to directly edit  
>>> PostGIS data using ArcGIS-like editing tools would be huge....but I  
>>> don't think that it would be easy and would probably be  
>>> cost-prohibitive.  As Paul mentioned, if these things were easily  
>>> and cost-effectively attainable, then it probably would have been  
>>> done by now.  But then again....look how successful mapserver has  
>>> become.  Just my thoughts......
>>>  Alex
>>> Paul Ramsey <pramsey at REFRACTIONS.NET> wrote:
>>> Guys, I am happy to spec this out again, but frankly I fear that  
>>> most solutions will remain in the "moderately ugly hack" domain, ala  
>>> PgArc. I have investigated more elegant things (oledb) but the signs  
>>> are not promising (http://arcgisdeveloperonline.esri.com/  
>>> ArcGISDeveloper/ExtendingArcObjects/Ch07/AboutOLEDBProviders.htm).  
>>> Principally, the continuing lack of an Oracle Spatial third party  
>>> read/write extension on the market says to me that such a thing is  
>>> just technically not possible to do attractively. If it were,  
>>> someone would have written it by now and be making money on it. If  
>>> anyone knows of such a thing, please do tell, it would be a good  
>>> positive sign of possible success.
>>> Paul
>>> On 7-Jul-05, at 10:22 AM, Ken Lord wrote:
>>>
>>>> Hi Mike,
>>>>
>>>> This is a major interest to us, we would like to see a push for  
>>>> this as well, in fact I was just asked to contact Tyler Mitchell  
>>>> about pgArc when I return from my holidays. Tyler! are your ears  
>>>> burning? hehe
>>>>
>>>> pgArc can be found at SourceForge if you want to check it out. It  
>>>> has some functionality with ArcGIS 8, but I haven't had it work  
>>>> with ArcGIS 9.
>>>>
>>>> We are locked into personal geodatabases for some of our clients,  
>>>> development of a fully functional ArcGIS / PostGIS connection would  
>>>> give us a lot more flexibility too.
>>>>
>>>> Cheers,
>>>> Ken Lord
>>>> Vancouver BC
>>>>
>>>>
>>>>
>>>>
>>>> On 7/7/05, Mike Davis wrote: Since we seem to be building some  
>>>> momentum on the ESRI personal
>>>> geodatabase thing, it seems like a good time to bring up the other
>>>> database related item on our wishlist.
>>>>
>>>> What would be required to allow read/write to a PostGIS database  
>>>> from
>>>> ArcGIS? I would love the ability to maintain our spatial data in
>>>> multiple datbase formats (must me my irrational fear of vendor
>>>> lock-in), but unless we can manage the data from within ArcGIS it
>>>> isn't really a practical option for us.
>>>>
>>>> -Mike
>>>>
>>> __________________________________________________
>>> Do You Yahoo!?
>>> Tired of spam?  Yahoo! Mail has the best spam protection around  
>>> http://mail.yahoo.com
>>>
>>
>>
>> -- 
>> geOps GeoInformatics
>> D-79100 Freiburg
>>
>>
      Paul Ramsey
      Refractions Research
      Email: pramsey at refractions.net
      Phone: (250) 885-0632