[ADD] dumpdb: doc

README.md

@@ -40,6 +40,7 @@ and provides helpers to run (and replay) migrations until it works.
     * [Command ``generate-module-analysis`` (BETA)](#command-generate-module-analysis)
     * [Command ``estimate-workload`` (BETA)](#command-estimate-workload)
     * [Command ``psql``](#command-psql)
+    * [Command ``dumpdb``](#command-dumpdb)
 
 <a name="installation"/>
 
@@ -435,3 +436,48 @@ Result:
 ```
 
 See all the options here https://www.postgresql.org/docs/current/app-psql.html
+
+<a name="command-dumpdb"/>
+
+## Command: ``dumpdb``
+
+**Prerequites:** init
+
+```
+odoo-openupgrade-wizard dumpdb
+    --database DB_NAME
+    --database-path DATABASE_PATH
+    --filestore-path FILESTORE_PATH
+```
+
+Dump the database DB_NAME to DATABASE_PATH and export the filestore
+related to DB_NAME into FILESTORE_PATH. To choose the format of the
+backup files look at the `--database-format` and `--filestore-format`.
+
+*WARNING*: DATABASE_PATH should be a sub directory of the project path
+in orter to have the postgresql container able to write the dump file.
+For example, the project path is `/path/to/myproject` (where you run the
+`init` command), then DATABASE_PATH can be any of the subdirectory of
+`/path/to/myproject`.
+
+**Optional arguments**
+
+* To chose the database format use `--database-format`. Format can be
+  one of the following:
+      - `p` for plain sql text
+      - `c` for custom compressed backup of `pg_dump`
+      - `d` for directory structure
+      - `t` for a tar version of the directory structure
+  See also https://www.postgresql.org/docs/current/app-pgdump.html
+  The default database format is `c`.
+
+* To chose the filestore format use `--filestore-format`. Format can be
+  one of the following:
+      - `d` copy of the directory structure
+      - `t` tar version of the directory structure (not compressed)
+      - `tgz` tar version of the directory structure compressed with gzip.
+  The default filestore format is `tgz`.
+
+* By default, if database file or filestore file already exists, the
+  command will fail, preserving the existing dump. If you need to
+  overwrite the existing files, the `--force` option can be used.