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Determine if line has true curves via SQL (SDE.ST_GEOMETRY in Oracle)

Bud

Currently, it's not possible to determine if a SDE.ST_GEOMETRY line has true curves via SQL.

For example, select lines where the SHAPE contains at least one true curve:

Could ESRI consider adding a function to SDE.ST_GEOMETRY (Oracle) for this purpose?

Something like:

SDE.ST_HasCurves()

Thanks.

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Status: Open

Comments

Bud

An untested idea from a colleague:

Since the data is stored in the st_geometry field you might be able to interrogate it for a flag value that indicates a true curve (slightly hacky, but might work) or look at the size of the blob and compare that to the number of points in the shape. There should be a correlation between the number of points and the size of the blob (but the points are compressed, so it isn’t 1:1), but if it’s greatly larger than what the size for the point array storage needs, it’s likely there is additional info in the blob (like true curves, annotation, or dimensions).

Bud

In the meantime, I wonder if this would be a possible workaround:

1. Create a field in the feature class called HAS_CURVES.

2. Populate the field in real-time/when a user creates or modifies a feature -- using a Calculation Attribute Rule.

Compare $feature.shape_length, which is the true length, including true curves
vs.
Length($feature), which is the pre-densified length, where true curves have been converted into straight segments.
https://i.stack.imgur.com/ilJrg.png
If there is a difference between those two values, then that tells us that the line has curves. Use a Calculation Attribute Rule to set the HAS_CURVES field to "Y".

3. That field would be available to SQL. So we could query on it as needed.

Disclaimer: It's possible that comparing the those lengths might not work in all scenarios (due to rounding complications, etc.). Testing would be needed. As the idea suggests, it would be a lot more robust to have a SDE.ST_HasCurves() function in ST_GEOMETRY.

Idea: hasCurve Arcade geometry property
Calculate length of line without using length function (and without densifying curves)
Select SDE.ST_GEOMETRY polylines that have arcs?