Add unit_load() function to load/update the data tables.

Author: df7cb

README.md

@@ -189,8 +189,13 @@ The [definitions.units](definitions.units) file is an interesting read on its
 own due to extensive comments explaining the history and origin of the units
 covered.
 
-User-Defined Units
-------------------
+The `unit_load()` function can be used to reload the `unit_prefixes.data` and
+`unit_units.data` files from disk. Extension upgrades use it to load newly
+added or changed definitions, but it is also user-callable. User-defined
+entries are preserved.
+
+User-Defined Prefixes and Units
+-------------------------------
 
 To create custom prefixes and units, insert new rows into the tables:
 
@@ -276,6 +281,7 @@ function stddev_samp(unit)
 function stddev(unit)
 function sum(unit)
 function unit_is_hashed(cstring)
+function unit_load()
 function unit_reset()
 function value(unit)
 function variance(unit)

debian/changelog

@@ -4,6 +4,7 @@ postgresql-unit (6.0-1) UNRELEASED; urgency=medium
     as double precision number.
   * Fix parsing of addition/subtraction in unit values.
   * Grant SELECT on unit prefixes and units table to public.
+  * Add unit_load() function to load/update the data tables.
 
  -- Christoph Berg <[email protected]>  Thu, 11 Jan 2018 20:49:44 +0100
 

unit--5--6.sql.in

@@ -1,5 +1,30 @@
 GRANT SELECT ON unit_prefixes, unit_units TO PUBLIC;
 
+CREATE OR REPLACE FUNCTION unit_load()
+	RETURNS VOID
+	LANGUAGE plpgsql
+	AS $$BEGIN
+DELETE FROM unit_prefixes WHERE dump IS NOT TRUE;
+CREATE TEMP TABLE tmp_prefixes (LIKE unit_prefixes) ON COMMIT DROP;
+COPY tmp_prefixes (prefix, factor, definition, dump) FROM '@MODULEDIR@/unit_prefixes.data';
+INSERT INTO unit_prefixes
+	SELECT * FROM tmp_prefixes t WHERE NOT EXISTS
+		(SELECT prefix FROM unit_prefixes u WHERE u.prefix = t.prefix);
+DROP TABLE tmp_prefixes;
+
+DELETE FROM unit_units WHERE dump IS NOT TRUE;
+CREATE TEMP TABLE tmp_units (LIKE unit_units) ON COMMIT DROP;
+COPY unit_units (name, unit, shift, definition, dump) FROM '@MODULEDIR@/unit_units.data';
+INSERT INTO unit_units
+	SELECT * FROM tmp_units t WHERE NOT EXISTS
+		(SELECT name FROM unit_units u WHERE u.name = t.name);
+DROP TABLE tmp_units;
+END;$$;
+
+COMMENT ON FUNCTION unit_load() IS 'Loads/upgrades the unit_units and unit_prefixes contents from the data files on disk';
+
+SELECT unit_load();
+
 CREATE FUNCTION unit_at_double(unit, text)
 	RETURNS double precision
 	SET search_path = @extschema@

unit--6.sql.in

@@ -45,8 +45,6 @@ CREATE TABLE unit_prefixes (
 
 SELECT pg_catalog.pg_extension_config_dump('unit_prefixes', 'WHERE dump');
 
-COPY unit_prefixes (prefix, factor, definition, dump) FROM '@MODULEDIR@/unit_prefixes.data';
-
 CREATE TABLE unit_units (
 	name varchar(32) PRIMARY KEY,
 	unit unit NOT NULL,
@@ -57,9 +55,32 @@ CREATE TABLE unit_units (
 
 SELECT pg_catalog.pg_extension_config_dump('unit_units', 'WHERE dump');
 
+GRANT SELECT ON unit_prefixes, unit_units TO PUBLIC;
+
+CREATE OR REPLACE FUNCTION unit_load()
+	RETURNS VOID
+	LANGUAGE plpgsql
+	AS $$BEGIN
+DELETE FROM unit_prefixes WHERE dump IS NOT TRUE;
+CREATE TEMP TABLE tmp_prefixes (LIKE unit_prefixes) ON COMMIT DROP;
+COPY tmp_prefixes (prefix, factor, definition, dump) FROM '@MODULEDIR@/unit_prefixes.data';
+INSERT INTO unit_prefixes
+	SELECT * FROM tmp_prefixes t WHERE NOT EXISTS
+		(SELECT prefix FROM unit_prefixes u WHERE u.prefix = t.prefix);
+DROP TABLE tmp_prefixes;
+
+DELETE FROM unit_units WHERE dump IS NOT TRUE;
+CREATE TEMP TABLE tmp_units (LIKE unit_units) ON COMMIT DROP;
 COPY unit_units (name, unit, shift, definition, dump) FROM '@MODULEDIR@/unit_units.data';
+INSERT INTO unit_units
+	SELECT * FROM tmp_units t WHERE NOT EXISTS
+		(SELECT name FROM unit_units u WHERE u.name = t.name);
+DROP TABLE tmp_units;
+END;$$;
 
-GRANT SELECT ON unit_prefixes, unit_units TO PUBLIC;
+COMMENT ON FUNCTION unit_load() IS 'Loads/upgrades the unit_units and unit_prefixes contents from the data files on disk';
+
+SELECT unit_load();
 
 -- constructors
 

unit.control

@@ -1,3 +1,7 @@
 default_version = '6'
-comment = 'unit extension'
+comment = 'SI units extension'
+# the unit_prefixes/unit_units tables can be installed in an arbitrary schema,
+# but can not be relocated later:
 relocatable = false
+# unit_load() is written in plpgsql:
+requires = 'plpgsql'