First stab at fixing /nearest#305
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The nearest postcode lookup performance reduced dramatically when tried with Postgres 9.6 and PostGIS 2.3. This commit updates the query to use the ‘<->’ centroid distance operator instead, which makes better use of the geoindex and is much faster to execute. Handily, the work @dracos did to introduce the TrigramDistance function into Django 1.10 was easily adaptable for this purpose, as the operator used is the same.
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Tweaked after merge to transform to 4326. And to fetch 100 rows and take actual closest, as we're using geometry not geography. |
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Something about the recent move to Postgres 9.6 and PostGIS 2.3 caused
the /nearest query to take much longer than 10 seconds to complete.
This commit updates the query to use the ‘<->’ centroid distance operator
instead, which makes better use of the geoindex and is much faster to
execute.
Handily the work @dracos did to introduce the TrigramDistance function
into Django 1.10 was easily adapted for this purpose, as it uses the
same operator.
This needs a bit of tidying and refactoring before merging really.