[postgis-tickets] [PostGIS] #4490: PG12: Review MVT functions cost

[PostGIS]

#4490: PG12: Review MVT functions cost
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  Reporter:  Raúl Marín   |      Owner:  Raúl Marín
      Type:  enhancement  |     Status:  assigned
  Priority:  medium       |  Milestone:  PostGIS 3.1.0
 Component:  postgis      |    Version:  master
Resolution:               |   Keywords:
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Comment (by Raúl Marín):

 I'm currently doing some tests around the PG12 costing and I see some
 inconsistencies.

 I guess that the initial costing was done by experience so I want to try
 something more empiric. My current aproach:
 - A fast operation over a gserialized geometry (no deserialization):
 _COST_DEFAULT (1). Example: ST_X.
 - A fast operation over a deserialized geometry: _COST_LOW COST 100.
 Example: ST_AsBinary
 - A medium operation over a deserialized geometry: _COST_MEDIUM COST 1000.
 Example: ST_AsText
 - A slow operation (anything 2x slower than ST_AsText): _COST_HIGH COST
 10000


 One important note is that I'm taking ST_AsText performance as a reference
 with the 5x improvement it has already placed in 3.1. Otherwise, ST_AsText
 should be high cost because it's specially slow in comparison with things
 like ST_Simplify or ST_AsMVTGeom.

 I'm only planning to do full tests with the functions I'm testing directly
 (which aren't many) but I'll do my best to group things (ST_AsText and
 ST_AsGeoJSON should have the same cost for example).

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/4490#comment:5>
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