updated help, fixed tables

.gitignore

@@ -0,0 +1 @@
+/tmp

README.md

@@ -16,6 +16,23 @@ options:
   --print-statements
 ```
 
+## Examples
+
+Export tables from source node
+```
+clickhouse_ddl_export.py --export /tmp/source_db_tables.json
+clickhouse_ddl_export.py --print-statements /tmp/source_db_tables.json > /tmp/ddl.sql
+```
+
+In destination node
+```
+clickhouse client --multiquery < /tmp/ddl.sql
+```
+
+Then replication is applied, and data is fetched from source node(s)
+
+Have fun!
+
 ## License
 
 ```text

clickhouse_ddl_export.py

@@ -45,17 +45,24 @@ def get_databases_tables(client):
 def export(dumpfile=DUMPFILE):
     client = clickhouse_connect.get_client(host='localhost', username='default', password='')
     databases = get_databases_tables(client)
+    print(f"exporting to {dumpfile}")
     with open(dumpfile, "w") as f:
         json.dump(databases, f, indent=4)
     return
 
 def dump(dumpfile=DUMPFILE):
+    try:
         with open(dumpfile, "r") as f:
             a = json.load(f)
             for database,values in a.items():
+                print(f"--- database {database} ---")
+                print(f"CREATE DATABASE {database};\n")
                 for table,c in values["tables"].items():
-                print(f"# {database}.{table}")
+                    print(f"-- table {database}.{table} --")
-                print(f"{c}\n")
+                    print(f"{c};\n")
+    except FileNotFoundError as e:
+        print(e)
+    print("to re-create replicas, run 'clickhouse-client --multiquery < generated_file.sql' on new replica server")
 
 def main():
     parser = argparse.ArgumentParser(
@@ -68,8 +75,10 @@ def main():
     args = parser.parse_args()
     if args.export:
         export(args.dumpfile)
-    if args.print_statements:
+    elif args.print_statements:
         dump(args.dumpfile)
+    else:
+        parser.print_help()
 
 if __name__ == "__main__":
     main()