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projinfo with EPSG:7842 slow #1913
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Probably not :-) I can't explain what's going on, but I can confirm the behaviour on my computer with 6.3.0 |
I don't get this order of mangitude of difference:
That is with sqlite 3.11. But if I use more recent sqlite versions, I also replicate the massive slowness. So likely a regression in the sqlite3 query optimizer. The added slowness is due to having PROJ.4 string output, which involves researching transformations to EPSG:4326. For EPSG:7842 which is a geocentric CRS, the search is more complicated Need to investigate what's going on |
OK, so what is slow is one of the 4 requests similar to the trivial below one (a bit simplified to remove bounding box tests which rely on a user-defined sqlite3 function):
The slowness is apparently due to the |
Fixes OSGeo#1913 AuthorityFactory::createBetweenGeodeticCRSWithDatumBasedIntermediates() issued a complex SQL query that pushes the SQLite3 query plan optimizer to its limits. Was working reasonably with sqlite 3.11, but not with later versions. So put less constraints in the main query and do post-processing checks and auxiliary requests to avoid such issues. For some unknown reason, this slightly slows down a bit execution time of the whole test_cpp_api binary (~ 10%), but couldn't come with something better, despite trying many variations of the main SQL query. It seems that in the general case the non-filter LEFT JOIN on the supersession table helped, except on this EPSG:7842 case.
Fixes OSGeo#1913 AuthorityFactory::createBetweenGeodeticCRSWithDatumBasedIntermediates() issued a complex SQL query that pushes the SQLite3 query plan optimizer to its limits. Was working reasonably with sqlite 3.11, but not with later versions. So put less constraints in the main query and do post-processing checks and auxiliary requests to avoid such issues. For some unknown reason, this slightly slows down a bit execution time of the whole test_cpp_api binary (~ 10%), but couldn't come with something better, despite trying many variations of the main SQL query. It seems that in the general case the non-filter LEFT JOIN on the supersession table helped, except on this EPSG:7842 case.
Fixes OSGeo#1913 AuthorityFactory::createBetweenGeodeticCRSWithDatumBasedIntermediates() issued a complex SQL query that pushes the SQLite3 query plan optimizer to its limits. Was working reasonably with sqlite 3.11, but not with later versions. So put less constraints in the main query and do post-processing checks and auxiliary requests to avoid such issues. For some unknown reason, this slightly slows down a bit execution time of the whole test_cpp_api binary (~ 10%), but couldn't come with something better, despite trying many variations of the main SQL query. It seems that in the general case the non-filter LEFT JOIN on the supersession table helped, except on this EPSG:7842 case.
Fixes OSGeo#1913 AuthorityFactory::createBetweenGeodeticCRSWithDatumBasedIntermediates() issued a complex SQL query that pushes the SQLite3 query plan optimizer to its limits. Was working reasonably with sqlite 3.11, but not with later versions. So put less constraints in the main query and do post-processing checks and auxiliary requests to avoid such issues. For some unknown reason, this slightly slows down a bit execution time of the whole test_cpp_api binary (~ 10%), but couldn't come with something better, despite trying many variations of the main SQL query. It seems that in the general case the non-filter LEFT JOIN on the supersession table helped, except on this EPSG:7842 case.
Running
is basically instant. But running
pegs out the CPU for about 5 seconds before exporting the WKT. Is this expected?
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