[postgis-tickets] [PostGIS] #4890: ST_Transform large slow down from upgrade to 3.1.1 from 2.4

[PostGIS]

#4890: ST_Transform large slow down from upgrade to 3.1.1 from 2.4
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  Reporter:  SAbernethy  |      Owner:  pramsey
      Type:  defect      |     Status:  closed
  Priority:  medium      |  Milestone:  PostGIS 3.1.2
 Component:  postgis     |    Version:  3.1.x
Resolution:  fixed       |   Keywords:
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Comment (by robe):

 @icehong why do you think that?

 The issue is that the Proj new API takes much longer to cache.  Like a 10
 to 100 times longer than Proj 5.2.  There is nothing we can do about that.
 The tests might be worded a little badly.

 What the regress_proj_cache_overflow is testing is rotating thru like 20
 SRIDs to make sure we don't crash the cache.  So it's more of a crasher
 test than a speed test.  So essentially to cost in new Proj of caching the
 20 or so spatial refs overshadows it's use.    It is what it is.

 As far as the proj_basic - it's more or less the same story.  I was
 thinking I should add more proj calls of the SRIDs loaded so that the
 caching does not overshadow the actual use.  It's like only 10 calls in
 there with 3 different projs right now.


 Question to @pramsey -- I assume we aren't caching proj in shared mem
 right (or are we) and it's only cached at the session level now?  That's
 the only thing I can think would help here, but maybe we are doing that
 already and it's just cause the tests are using different projs that we
 don't see the effect.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4890#comment:20>
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