[postgis-devel] Deprecate ST_MapAlgebraExpr and ST_MapAlgebraFct

[dustymugs]

I do plan on tacking on notices indicating the deprecate status to those
functions.

-bborie

On 10/10/2012 01:24 PM, Paragon Corporation wrote:
> I like it.
> 
> +1
> 
> I think now is a good time to deprecate before people start heavily using
> the current names.
> 
>  
> Thanks,
> Regina
> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net
> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of
> dustymugs
> Sent: Wednesday, October 10, 2012 4:03 PM
> To: PostGIS Development Discussion
> Subject: [postgis-devel] Deprecate ST_MapAlgebraExpr and ST_MapAlgebraFct
> 
> Hey all,
> 
> I'm planning on committing support for n-raster (and n-band) map algebra as
> ST_MapAlgebra().  This new map algebra function only works on user-specified
> callback functions as trying to support an expression-based n-raster with
> neighborhood would be extremely cumbersome.  Think of the number of keywords
> required if you have variable size neighborhoods and unlimited number of
> rasters and bands...
> 
> I'd like to deprecate all variants of ST_MapAlgebraExpr, ST_MapAlgebraFct
> and ST_MapAlgebraFctNgb in 2.1 with eventual removal in 2.2.  The use of
> Expr, Fct, FctNgb suffixes is tedious and the variants for 1 raster and 2
> rasters is confusing for users and horrible to maintain in the codebase.
> 
> As for removing expression-based map algebra, historical testing showed that
> performance of callback functions was consistently faster than expressions
> (even with use of prepared statements).  Not to mention the ease of
> debugging a function rather than an expression where the problem could be in
> the user's expression or how that expression is parsed.
> 
> This simplification unifies everything and keeps things simple and stupid.
> 
> Thoughts?
> 
> -bborie
> 
> PS: Before anyone goes nuts, I don't plan on replacing the existing code for
> Expr, Fct and FctNgb variants.  I'm only adding ST_MapAlgebra() for 2.1.
> The Expr, Fct and FctNgb variants will be removed in 2.2.
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