churn: Remove systems.relorder column + misc cleanup

sql/update-2021-12-13.sql

@@ -0,0 +1,44 @@
+CREATE OR REPLACE FUNCTION match_firstchar(str text, chr text) RETURNS boolean AS $$
+  SELECT CASE WHEN chr = '0'
+         THEN (ascii(str) < 97 OR ascii(str) > 122) AND (ascii(str) < 65 OR ascii(str) > 90)
+         ELSE ascii(str) IN(ascii(chr),ascii(upper(chr)))
+         END;
+$$ LANGUAGE SQL IMMUTABLE;
+
+
+ALTER TABLE packages DROP CONSTRAINT packages_system_fkey;
+ALTER TABLE packages ADD CONSTRAINT packages_system_fkey FOREIGN KEY (system) REFERENCES systems(id) ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- Remapping system IDs so we can sort on that rather than 'relorder'
+-- (Yes, this means adding a new system somewhere in-between requires changing
+-- system IDs again, but that's fine, these IDs are only used internally)
+BEGIN;
+WITH map(old,new) AS (
+    -- FreeBSD
+          SELECT  80,  84
+    UNION SELECT  84,  80
+    UNION SELECT 132,  99
+    UNION SELECT  99, 129
+    UNION SELECT 129, 132
+    UNION SELECT 188, 198
+    UNION SELECT 192, 188
+    UNION SELECT 198, 203
+    UNION SELECT 203, 192
+    -- CentOS
+    UNION SELECT 175, 176 
+    UNION SELECT 176, 177 
+    UNION SELECT 177, 178 
+    UNION SELECT 178, 179 
+    UNION SELECT 179, 182 
+    UNION SELECT 182, 183 
+    UNION SELECT 183, 175 
+    UNION SELECT 195, 200 
+    UNION SELECT 196, 201 
+    UNION SELECT 200, 195 
+    UNION SELECT 201, 206 
+    UNION SELECT 206, 196 
+) UPDATE systems SET id = new+10000 FROM map WHERE id = old;
+UPDATE systems SET id = id-10000 WHERE id >= 10000;
+COMMIT;
+
+ALTER TABLE systems DROP COLUMN relorder;