feat: keep track of latest pact revision in table rather than calcula…

…ting it

db/migrations/000028_create_all_pact_publications.rb

@@ -21,7 +21,8 @@
       group by provider_id, consumer_id, consumer_version_order"
     )
 
-    # Latest pact_publication details for each consumer version
+    # Latest pact_publication (revision) for each provider/consumer version
+    # updated in 20180519_recreate_views.rb
     create_view(:latest_pact_publications_by_consumer_versions,
       "select app.*
       from all_pact_publications app
@@ -33,6 +34,8 @@
         )
 
 
+    # updated in 20180519_recreate_views.rb
+    # This view tells us the latest consumer version with a pact for a consumer/provider pair
     create_or_replace_view(:latest_pact_consumer_version_orders,
       "select provider_id, consumer_id, max(consumer_version_order) as latest_consumer_version_order
       from all_pact_publications

db/migrations/20180517_create_latest_pact_publication_ids.rb

@@ -0,0 +1,21 @@
+Sequel.migration do
+  up do
+    # Latest pact_publication (revision) for each provider/consumer version.
+    # Keeping track of this in a table rather than having to calculate the
+    # latest revision speeds things up.
+    # We don't have to worry about updating it if a revision is deleted, because
+    # you can't delete a single revision through the API - all the revisions
+    # for a pact are deleted together when you delete the pact resource for that
+    # consumer version, and when that happens, this row will cascade delete.
+    create_table(:latest_pact_publication_ids_by_consumer_versions, charset: 'utf8') do
+      foreign_key :consumer_version_id, :versions, nil: false, on_delete: :cascade
+      foreign_key :provider_id, :pacticipants, nil: false, on_delete: :cascade
+      foreign_key :pact_publication_id, :pact_publications, nil: false, on_delete: :cascade
+      index [:provider_id, :consumer_version_id], unique: true, name: "unq_latest_ppid_prov_conver"
+    end
+  end
+
+  down do
+    drop_table(:latest_pact_publication_ids_by_consumer_versions)
+  end
+end

db/migrations/20180518_migrate_latest_pact_publication_ids.rb

@@ -0,0 +1,11 @@
+Sequel.migration do
+  up do
+    # The danger with this migration is that a pact publication created by an old node will be lost
+    rows = from(:latest_pact_publications_by_consumer_versions).select(:consumer_version_id, :provider_id, :id)
+    from(:latest_pact_publication_ids_by_consumer_versions).insert(rows)
+  end
+
+  down do
+
+  end
+end

db/migrations/20180519_recreate_views.rb

@@ -0,0 +1,43 @@
+Sequel.migration do
+  up do
+    # Latest pact_publication details for each provider/consumer version
+    create_or_replace_view(:latest_pact_publications_by_consumer_versions,
+      "select app.*
+      from latest_pact_publication_ids_by_consumer_versions lpp
+      inner join all_pact_publications app
+      on lpp.consumer_version_id = app.consumer_version_id
+      and lpp.pact_publication_id = app.id
+      and lpp.provider_id = app.provider_id"
+    )
+
+    # Latest consumer version order for consumer/provider
+    # Recreate latest_pact_publication_ids_by_consumer_versions view
+    lpp = :latest_pact_publication_ids_by_consumer_versions
+    latest_pact_consumer_version_orders = from(lpp).select_group(
+        Sequel[lpp][:provider_id],
+        Sequel[:cv][:pacticipant_id].as(:consumer_id))
+      .select_append{ max(order).as(latest_consumer_version_order) }
+      .join(:versions, { Sequel[lpp][:consumer_version_id] => Sequel[:cv][:id] }, { table_alias: :cv })
+
+    create_or_replace_view(:latest_pact_consumer_version_orders, latest_pact_consumer_version_orders)
+  end
+
+  down do
+    # Latest pact_publication details for each provider/consumer version
+    create_or_replace_view(:latest_pact_publications_by_consumer_versions,
+      "select app.*
+      from all_pact_publications app
+      inner join latest_pact_publication_revision_numbers lr
+      on app.consumer_id = lr.consumer_id
+        and app.provider_id = lr.provider_id
+        and app.consumer_version_order = lr.consumer_version_order
+        and app.revision_number = lr.latest_revision_number"
+        )
+
+    create_or_replace_view(:latest_pact_consumer_version_orders,
+      "select provider_id, consumer_id, max(consumer_version_order) as latest_consumer_version_order
+      from all_pact_publications
+      group by provider_id, consumer_id"
+    )
+  end
+end