Clarify migration steps for overviews table issue

src/server/upgrade/create_map_overview.sql

@@ -0,0 +1,33 @@
+-- ============================================================
+-- PATCH: Create map_overview table
+-- ============================================================
+
+BEGIN;
+
+CREATE SEQUENCE IF NOT EXISTS public.map_overview_id_seq;
+
+CREATE TABLE IF NOT EXISTS public.map_overview
+(
+    id              INTEGER           NOT NULL DEFAULT nextval('map_overview_id_seq'::regclass),
+    project_id      UUID              NOT NULL,
+    version         CHARACTER VARYING,
+    config          JSON,
+    data_location   CHARACTER VARYING,
+    qgis_file       CHARACTER VARYING,
+
+    CONSTRAINT pk_map_overview
+        PRIMARY KEY (id, project_id),
+
+    CONSTRAINT fk_map_overview_project_id_project
+        FOREIGN KEY (project_id)
+        REFERENCES public.project (id)
+        ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS ix_map_overview_project_id
+    ON public.map_overview (project_id ASC NULLS LAST);
+
+CREATE INDEX IF NOT EXISTS ix_map_overview_version
+    ON public.map_overview (version ASC NULLS LAST);
+
+COMMIT;

src/server/upgrade/index.md

@@ -71,7 +71,51 @@ You can also clean the following variables from `.prod.env`:
     $ docker exec merginmaps-server flask db stamp 6cb54659c1de
     $ docker exec merginmaps-server flask db stamp e95d051969ce
     ```
-8. Run the database migration:
+
+8. If you do not have `map_overview` table in your database, run the following commands to create it by running commands in postgres container or in any postgres client (PgAdmin, etc.) connected to your database:
+    ```bash
+    $ docker exec -it merginmaps-db bash
+    $ psql -U postgres
+    ```
+
+    Run following SQL for creating the `map_overview` table and its indexes:
+
+    ```sql
+    BEGIN;
+
+    CREATE SEQUENCE IF NOT EXISTS public.map_overview_id_seq;
+
+    CREATE TABLE IF NOT EXISTS public.map_overview
+    (
+        id              INTEGER           NOT NULL DEFAULT nextval('map_overview_id_seq'::regclass),
+        project_id      UUID              NOT NULL,
+        version         CHARACTER VARYING,
+        config          JSON,
+        data_location   CHARACTER VARYING,
+        qgis_file       CHARACTER VARYING,
+
+        CONSTRAINT pk_map_overview
+            PRIMARY KEY (id, project_id),
+
+        CONSTRAINT fk_map_overview_project_id_project
+            FOREIGN KEY (project_id)
+            REFERENCES public.project (id)
+            ON DELETE CASCADE
+    );
+
+    CREATE INDEX IF NOT EXISTS ix_map_overview_project_id
+        ON public.map_overview (project_id ASC NULLS LAST);
+
+    CREATE INDEX IF NOT EXISTS ix_map_overview_version
+        ON public.map_overview (version ASC NULLS LAST);
+
+    COMMIT;
+   ```
+
+If this table is missing, the migrations in the next step will fail.
+
+9. Run the database migration:
+
     ```bash
     $ docker exec merginmaps-server flask db upgrade community@b9ec9ab6694f
     $ docker exec merginmaps-server flask db upgrade enterprise@c40e5e645b57