refactor(DB): DB delta

ee/scripts/schema/db/init_dbs/postgresql/1.20.0/1.20.0.sql

@@ -0,0 +1,31 @@
+\set previous_version 'v1.19.0-ee'
+\set next_version 'v1.20.0-ee'
+SELECT openreplay_version()                       AS current_version,
+       openreplay_version() = :'previous_version' AS valid_previous,
+       openreplay_version() = :'next_version'     AS is_next
+\gset
+
+\if :valid_previous
+\echo valid previous DB version :'previous_version', starting DB upgrade to :'next_version'
+BEGIN;
+SELECT format($fn_def$
+CREATE OR REPLACE FUNCTION openreplay_version()
+    RETURNS text AS
+$$
+SELECT '%1$s'
+$$ LANGUAGE sql IMMUTABLE;
+$fn_def$, :'next_version')
+\gexec
+
+--
+ALTER TABLE IF EXISTS events.clicks
+    ALTER COLUMN normalized_x SET DATA TYPE decimal,
+    ALTER COLUMN normalized_y SET DATA TYPE decimal;
+
+COMMIT;
+
+\elif :is_next
+\echo new version detected :'next_version', nothing to do
+\else
+\warn skipping DB upgrade of :'next_version', expected previous version :'previous_version', found :'current_version'
+\endif