Fix demo to run as memory only

slides/overview.slide

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+Super Graph
+Instant GraphQL API for Rails. Zero Code.
+Tags: GraphQL, API, GoLang, Postgres
+
+Vikram Rangnekar 
+https://twitter.com/@dosco
+
+
+* Motivation
+
+- Honestly, cause it was more fun than my real work.  
+- Bored of building yet anther CRUD API
+- Save hours of my life
+- Easier to use advanced Postgres features
+- Always get secure, optimized queries
+- Quickly add GraphQL to existing apps
+
+* Got Web UI?
+
+.image https://supergraph.dev/super-graph-web-ui.png _ 1000
+
+* What does it do?
+
+- Add a GraphQL API to any Rails app with zero code
+- Automatically learns schemas and relationships
+- Supports Belongs-To, One-To-Many and Many-To-Many relationships
+- Full text search and Aggregations
+- Rails Auth supported (Redis, Memcache, Cookie)
+- JWT tokens supported (Auth0, etc)
+- Highly optimized and fast Postgres SQL queries
+
+* How does it work?
+
+GraphQL Input
+  
+  query {
+    users{
+      email
+      id
+    }
+  }
+
+SQL Output
+
+  SELECT 
+    "users_0"."email"     AS "email", 
+    "users_0"."id"        AS "id"
+  FROM   ( 
+    SELECT 
+      "users"."email", 
+      "users"."id" 
+    FROM "users" 
+    WHERE ((("users"."id") = ('4'))) limit ('20') :: integer) 
+    LIMIT ('20') :: integer)) 
+
+* Advanced Queries made simple
+
+  query {
+    products(
+      # Search for all products that contain 'ale' or some version of it
+      search: "ale"
+
+      # Return only matches where the price is less than 10
+      where: { price: { lt: 10 } }
+
+      # Use the search_rank to order from the best match to the worst
+      order_by: { search_rank: desc }) {
+
+      id
+      name
+      search_rank
+      search_headline_description
+    }
+  }
+
+* Easy to configure
+
+  database:
+    variables:
+      account_id: "select account_id from users where id = $user_id"
+
+    defaults:
+      filter: ["{ user_id: { eq: $user_id } }"]
+
+      blacklist:
+        - password
+        - secret_token
+
+  fields:
+    - name: users
+      filter: ["{ id: { eq: $user_id } }"]
+
+    - name: products
+      filter: [
+        "{ price: { gt: 0 } }",
+        "{ price: { lt: 8 } }"
+      ]
+
+    - name: me
+      table: users
+      filter: ["{ id: { eq: $user_id } }"]