From a87f358253cc906fad3342f42eabe0bf86457269 Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@keybit.net>
Date: Tue, 22 Oct 2013 18:16:57 +0200
Subject: [PATCH] Add drop table handler, manage CDB_TableMetadata entries on
 create/drop

---
 cartodb_hooks.sql        | 33 ++++++++++++++++++++++++++++++---
 hook_on_table_create.sql |  6 ++++++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/cartodb_hooks.sql b/cartodb_hooks.sql
index 4915bb6..23ec215 100644
--- a/cartodb_hooks.sql
+++ b/cartodb_hooks.sql
@@ -29,6 +29,31 @@ BEGIN
   -- CDB_CartodbfyTable must not create tables, or infinite loop will happen
   PERFORM public.CDB_CartodbfyTable(event_info.relation);
 
+  -- Add entry to CDB_TableMetadata (should CartodbfyTable do this?)
+  INSERT INTO public.CDB_TableMetadata(tabname,updated_at) 
+  VALUES (event_info.relation, now());
+
+END; $$;
+-- }
+
+-- Table drop
+-- {
+CREATE OR REPLACE FUNCTION cdb_handle_drop_table ()
+RETURNS event_trigger SECURITY DEFINER LANGUAGE plpgsql AS $$
+DECLARE
+  event_info RECORD;
+BEGIN
+  event_info := schema_triggers.get_relation_drop_eventinfo();
+
+  -- We're only interested in real relations
+  IF (event_info.old).relkind != 'r' THEN RETURN; END IF;
+
+  RAISE DEBUG 'Relation % of kind % dropped from namespace oid %',
+	 event_info.old_relation_oid, (event_info.old).relkind, (event_info.old).relnamespace;
+
+  -- delete record from CDB_TableMetadata (should invalidate varnish)
+  DELETE FROM public.CDB_TableMetadata WHERE tabname = event_info.old_relation_oid;
+
 END; $$;
 -- }
 
@@ -62,7 +87,7 @@ BEGIN
 
   PERFORM cdb_enable_ddl_hooks();
 
-  -- TODO: invalidate varnish 
+  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
 
 END; $$;
 -- }
@@ -97,7 +122,7 @@ BEGIN
 
   PERFORM cdb_enable_ddl_hooks();
 
-  -- TODO: invalidate varnish 
+  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
 
 END; $$;
 -- }
@@ -126,13 +151,14 @@ BEGIN
     RETURN;
   END IF;
 
-  -- TODO: invalidate varnish
+  -- TODO: update CDB_TableMetadata.updated_at (should invalidate varnish)
 
 END; $$;
 -- }
 
 CREATE OR REPLACE FUNCTION cdb_disable_ddl_hooks() returns void AS $$
  DROP EVENT TRIGGER IF EXISTS cdb_on_relation_create;
+ DROP EVENT TRIGGER IF EXISTS cdb_on_relation_drop;
  DROP EVENT TRIGGER IF EXISTS cdb_on_alter_column;
  DROP EVENT TRIGGER IF EXISTS cdb_on_drop_column;
  DROP EVENT TRIGGER IF EXISTS cdb_on_add_column;
@@ -141,6 +167,7 @@ $$ LANGUAGE sql;
 CREATE OR REPLACE FUNCTION cdb_enable_ddl_hooks() returns void AS $$
  SELECT cdb_disable_ddl_hooks();
  CREATE EVENT TRIGGER cdb_on_relation_create ON "relation_create" EXECUTE PROCEDURE cdb_handle_create_table();
+ CREATE EVENT TRIGGER cdb_on_relation_drop ON "relation_drop" EXECUTE PROCEDURE cdb_handle_drop_table();
  CREATE EVENT TRIGGER cdb_on_alter_column ON "column_alter" EXECUTE PROCEDURE cdb_handle_alter_column();
  CREATE EVENT TRIGGER cdb_on_drop_column ON "column_drop" EXECUTE PROCEDURE cdb_handle_drop_column();
  CREATE EVENT TRIGGER cdb_on_add_column ON "column_add" EXECUTE PROCEDURE cdb_handle_add_column();
diff --git a/hook_on_table_create.sql b/hook_on_table_create.sql
index e9b9a3a..e972ddc 100644
--- a/hook_on_table_create.sql
+++ b/hook_on_table_create.sql
@@ -10,12 +10,18 @@ create schema c;
 --create table c.t3(a int);
 select 1 as i INTO c.t3;
 select * from c.t3;
+select tabname::text, updated_at from CDB_TableMetadata;
 alter table c.t3 rename column the_geom_webmercator to webmerc;
 select * from c.t3;
+select tabname::text, updated_at from CDB_TableMetadata;
 alter table c.t3 rename column the_geom_webmercator to webmerc2;
 select * from c.t3;
+select tabname::text, updated_at from CDB_TableMetadata;
 alter table c.t3 drop column the_geom_webmercator;
 select * from c.t3;
+select tabname::text, updated_at from CDB_TableMetadata;
 alter table c.t3 add column id2 int;
 select * from c.t3;
+select tabname::text, updated_at from CDB_TableMetadata;
 drop schema c cascade;
+select tabname::text, updated_at from CDB_TableMetadata;