Here are lists of some useful internal Shardman tables.

For example:

postgres=# select * from shardman.sequence;
 seqns  | seqname | seqmin |       seqmax        | seqblk 
--------+---------+--------+---------------------+--------
 public | s       |      1 | 9223372036854775807 |  65536
(1 row)

postgres=# select * from shardman.sharded_tables;
  rel  | nparts | colocated_with | relname | nspname 
-------+--------+----------------+---------+---------
 16648 |     20 |                | d       | public
 16741 |     20 |          16648 | c       | public
(2 rows)

postgres=# select * from shardman.global_tables; 
 relid | main_rgid | relname | nspname 
-------+-----------+---------+---------
 16636 |           | g       | public
(1 row)
    

To do this, use the shardman.broadcast_all_sql function and shardmanctl forall option. For example:

postgres$ shardmanctl forall --sql "select name,setting from pg_settings where name = 'max_connections'"
SQL: select name,setting from pg_settings where name = 'max_connections'
Node 1 says:
[max_connections 90]
Node 2 says:
[max_connections 90]
    

To do this, use this query:

postgres=# SELECT name,setting FROM pg_catalog.pg_settings WHERE name ~ 'shardman.';
                   name                    |               setting                
-------------------------------------------+--------------------------------------
 shardman.broadcast_ddl                    | off
 shardman.cluster_uuid                     | 818e4a38-4675-4bd2-8070-01ccad48f031
 shardman.config_uuid                      | 0387f597-105c-4697-9a2b-c8779689d469
 shardman.database                         | postgres
 shardman.enable_limit_pushdown            | on
 shardman.fail_after_prepare               | off
 shardman.fail_before_commit_prepared      | off
 shardman.fail_before_prepare              | off
 shardman.manual_execution                 | off
 shardman.monitor_deadlock_interval        | 2
 shardman.monitor_dxact_interval           | 5
 shardman.monitor_dxact_timeout            | 5
 shardman.monitor_interval                 | 0
 shardman.monitor_trim_csnxid_map_interval | 5
 shardman.num_parts                        | 20
 shardman.pre_promote_mode                 | off
 shardman.query_engine_mode                | text
 shardman.rgid                             | 1
 shardman.silk_blocks_bk                   | -1
 shardman.silk_blocks_worms                | off
 shardman.silk_enabled                     | on
 shardman.silk_listen_ip                   | node1
 shardman.silk_max_message                 | 524288
 ...
    

Besides, you can use shardmanctl config get command to obtain cluster configuration from etcd. You can view the parameters, but it is better to customize them after consulting with Posgres Pro engineers.

You can use shardmanctl config update functionality, see an example.