[fdo-dev] FDO172 & Warning of "build breaker" changes

[Pierre Dalcourt]

Hi Frank,

This method is used to indicate the theoretical maximum size of data
values that can be read/written using the given provider.  I'm not 100%
sure which client(s) will be using these capabilities.

The value "-1" in such capability APIs indicates that there is
theoretically no limit, although in practice there may be a real limit
imposed by several factors (file system size, etc).  In the case of SHP
Provider's Blob/Clob size limits, -1 is returned but should be ignored
by the caller because SHP Provider does not support Blobs/Clobs as of
this time.

In the case of a value as large as 2^63 there may not be a significant
difference between returning 2^63 or -1 but if you have an accurate
maximum value it would be best to return it instead of -1.

Pierre

-----Original Message-----
From: Frank Warmerdam (External) 
Sent: September 26, 2006 9:34 AM
To: dev at fdo.osgeo.org
Subject: Re: [fdo-dev] FDO172 & Warning of "build breaker" changes


Folks,

On a related point, I'm not sure how to implement
ISChemaCapabilities::GetMaximumDataValueLength().

Is this method just used when creating new fields?  I see the shape
provider returns -1 for some field types.  Does this imply unlimited
or unsupported?

For my raster provider the upper size of a BLOB is in theory 2^63 or
so.  Should I return that?

Best regards,
-- 
---------------------------------------+--------------------------------
------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo,
http://osgeo.org


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