Stop creating views

Fixes #1950

Author: kderme

schema/migration-1-0002-20190912.sql

@@ -1,34 +1,19 @@
--- Drop all VIEWs linked to the 'cexplorer' table.
 
--- Many schema migration changes will fail if they operate on a table that is part of a VIEW.
--- So we drop all VIEWs here and recreate them later.
-
-CREATE FUNCTION drop_cexplorer_views () RETURNS void language plpgsql as $$
-
-DECLARE vname text;
-DECLARE next_version int;
 
+CREATE FUNCTION migrate() RETURNS void AS $$
+DECLARE
+  next_version int ;
 BEGIN
-  SELECT stage_one + 1 INTO next_version FROM "schema_version";
+  SELECT stage_one + 1 INTO next_version FROM "schema_version" ;
   IF next_version = 2 THEN
-    -- Only update the schema version if the versions are as expected.
-    UPDATE "schema_version" SET stage_one = next_version;
-    RAISE NOTICE 'DB has been migrated to stage_one version %', next_version;
-  END IF;
+    -- Empty migration file just to raise the version
 
-  -- Always run the following.
-  for vname in
-      select '"' || table_name || '"'
-	    from information_schema.views
-        where table_catalog = current_database ()
-          and table_schema = 'public'
-          and table_name !~* 'pg_stat_.*'
-    loop
-      execute format ('drop view if exists %s cascade ;', vname) ;
-      raise notice 'Dropping view : %', vname ;
-    end loop ;
-end $$ ;
+    UPDATE schema_version SET stage_one = next_version ;
+    RAISE NOTICE 'DB has been migrated to stage_one version %', next_version ;
+  END IF ;
+END ;
+$$ LANGUAGE plpgsql ;
 
-SELECT drop_cexplorer_views () ;
+SELECT migrate() ;
 
-DROP FUNCTION drop_cexplorer_views () ;
+DROP FUNCTION migrate() ;

schema/migration-3-0001-20190816.sql

@@ -1,28 +0,0 @@
--- Create all the views.
-
--- The views are always created because all views are deleted at the start ot the
--- migration process.
-
--- Conventions:
---  * Views use `_view` as a suffix to show they are views rather than table.
-
--- A utxo view which shows all unspent transaction outputs including the un-redeemed redeem
--- addresses.
-create or replace view  utxo_byron_view as select
-	tx_out.*
-  from tx_out left outer join tx_in
-	on tx_out.tx_id = tx_in.tx_out_id and tx_out.index = tx_in.tx_out_index
-  where tx_in.tx_in_id is null ;
-
-
--- A utxo view which shows all unspent transaction outputs *excluding* the un-redeemed redeem
--- addresses.
--- This should produce the same query results as the above `utxo_byron_view` for Shelley addresses
--- and non-redeem Byron addresses.
-create or replace view utxo_view as select
-	tx_out.*
-  from tx_out
-	left outer join tx_in on tx_out.tx_id = tx_in.tx_out_id and tx_out.index = tx_in.tx_out_index
-	left outer join tx on tx.id = tx_out.tx_id
-	left outer join block on tx.block_id = block.id
-  where tx_in.tx_in_id is null and block.epoch_no is not null ;