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https://gitlab.com/wgp/dougal/software.git
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23de4d00d7
This defines a interpolate_geometry_from_tstamp(), taking a timestamp and a maximum timespan in seconds. It will then interpolate a position at the exact timestamp based on data from real_time_inputs, provided that the effective interpolation timespan does not exceed the maximum requested. Fixes #243.
128 lines
3.0 KiB
PL/PgSQL
128 lines
3.0 KiB
PL/PgSQL
-- Fix not being able to edit a time-based event.
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--
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-- New schema version: 0.3.10
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--
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-- ATTENTION:
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--
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-- ENSURE YOU HAVE BACKED UP THE DATABASE BEFORE RUNNING THIS SCRIPT.
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--
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--
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-- NOTE: This upgrade affects only the public schema.
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-- NOTE: Each application starts a transaction, which must be committed
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-- or rolled back.
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--
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-- This defines a interpolate_geometry_from_tstamp(), taking a timestamp
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-- and a maximum timespan in seconds. It will then interpolate a position
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-- at the exact timestamp based on data from real_time_inputs, provided
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-- that the effective interpolation timespan does not exceed the maximum
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-- requested.
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--
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-- To apply, run as the dougal user:
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--
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-- psql <<EOF
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-- \i $THIS_FILE
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-- COMMIT;
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-- EOF
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--
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-- NOTE: It can be applied multiple times without ill effect.
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--
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BEGIN;
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CREATE OR REPLACE PROCEDURE pg_temp.show_notice (notice text) AS $$
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BEGIN
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RAISE NOTICE '%', notice;
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END;
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$$ LANGUAGE plpgsql;
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CREATE OR REPLACE PROCEDURE pg_temp.upgrade () AS $outer$
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BEGIN
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CALL pg_temp.show_notice('Defining interpolate_geometry_from_tstamp()');
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CREATE OR REPLACE FUNCTION public.interpolate_geometry_from_tstamp(
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IN ts timestamptz,
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IN maxspan numeric
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)
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RETURNS geometry
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AS $$
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DECLARE
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ts0 timestamptz;
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ts1 timestamptz;
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geom0 geometry;
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geom1 geometry;
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span numeric;
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fraction numeric;
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BEGIN
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SELECT tstamp, geometry
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INTO ts0, geom0
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FROM real_time_inputs
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WHERE tstamp <= ts
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ORDER BY tstamp DESC
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LIMIT 1;
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SELECT tstamp, geometry
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INTO ts1, geom1
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FROM real_time_inputs
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WHERE tstamp >= ts
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ORDER BY tstamp ASC
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LIMIT 1;
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IF geom0 IS NULL OR geom1 IS NULL THEN
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RAISE NOTICE 'Interpolation failed (no straddling data)';
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RETURN NULL;
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END IF;
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-- See if we got an exact match
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IF ts0 = ts THEN
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RETURN geom0;
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ELSIF ts1 = ts THEN
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RETURN geom1;
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END IF;
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span := extract('epoch' FROM ts1 - ts0);
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IF span > maxspan THEN
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RAISE NOTICE 'Interpolation timespan % outside maximum requested (%)', span, maxspan;
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RETURN NULL;
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END IF;
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fraction := extract('epoch' FROM ts - ts0) / span;
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IF fraction < 0 OR fraction > 1 THEN
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RAISE NOTICE 'Requested timestamp % outside of interpolation span (fraction: %)', ts, fraction;
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RETURN NULL;
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END IF;
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RETURN ST_LineInterpolatePoint(St_MakeLine(geom0, geom1), fraction);
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END;
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$$ LANGUAGE plpgsql;
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COMMENT ON FUNCTION public.interpolate_geometry_from_tstamp(timestamptz, numeric) IS
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'Interpolate a position over a given maximum timespan (in seconds)
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based on real-time inputs. Returns a POINT geometry.';
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END;
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$outer$ LANGUAGE plpgsql;
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CALL pg_temp.upgrade();
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CALL pg_temp.show_notice('Cleaning up');
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DROP PROCEDURE pg_temp.upgrade ();
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CALL pg_temp.show_notice('Updating db_schema version');
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INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.10"}')
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ON CONFLICT (key) DO UPDATE
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SET value = public.info.value || '{"db_schema": "0.3.10"}' WHERE public.info.key = 'version';
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CALL pg_temp.show_notice('All done. You may now run "COMMIT;" to persist the changes');
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DROP PROCEDURE pg_temp.show_notice (notice text);
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--
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--NOTE Run `COMMIT;` now if all went well
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--
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