[search_title] tsvector query fix for v11

Also, pin postgres to v11 so that we're compatible with Debian
upstream.

devops/docker/docker-compose.yaml

@@ -2,7 +2,8 @@ version: '3'
 
 services:
   postgres:
-    image: 'postgres:latest'
+    #image: 'postgres:latest'
+    image: 'postgres:11'
     network_mode: host
     #ports:
       #- 5432:5432

devops/postgres/schema.sql

@@ -38,9 +38,9 @@ CREATE TABLE public.nodes (
     FOREIGN KEY (user_id)  REFERENCES public.auth_user(id) ON DELETE CASCADE
 );
 ALTER TABLE public.nodes OWNER TO gargantua;
-ALTER TABLE nodes
-    ADD COLUMN search_title tsvector
-               GENERATED ALWAYS AS (to_tsvector('english', coalesce("hyperdata"->>'title', '') || ' ' || coalesce("hyperdata"->>'abstract', ''))) STORED;
+ALTER TABLE nodes ADD COLUMN search_title tsvector;
+UPDATE nodes SET search_title = to_tsvector('english', coalesce("hyperdata"->>'title', '') || ' ' || coalesce("hyperdata"->>'abstract', ''));
+CREATE INDEX search_title_idx ON nodes USING GIN (search_title);
 
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