Fixes#271
This change sets ShardIds and JobIds for each test case. Before this change,
when a new test that somehow increments Job or Shard IDs is added, then
the tests after the new test should be updated.
ShardID and JobID sequences are set at the beginning of each file with the
following commands:
```
ALTER SEQUENCE pg_catalog.pg_dist_shardid_seq RESTART 290000;
ALTER SEQUENCE pg_catalog.pg_dist_jobid_seq RESTART 290000;
```
ShardIds and JobIds are multiples of 10000. Exceptions are:
- multi_large_shardid: shardid and jobid sequences are set to much larger values
- multi_fdw_large_shardid: same as above
- multi_join_pruning: Causes a race condition with multi_hash_pruning since
they are run in parallel.
After this change, shards and associated metadata are automatically
dropped when running DROP TABLE on a distributed table, which fixes#230.
It also adds schema support for master_apply_delete_command, which
fixes#73.
Dropping the shards happens in the master_drop_all_shards UDF, which is
called from the SQL_DROP trigger. Inside the trigger, the table is no
longer visible and calling master_apply_delete_command directly wouldn't
work and oid <-> name mappings are not available. The
master_drop_all_shards function therefore takes the relation id, schema
name, and table name as parameters, which can be obtained from
pg_event_trigger_dropped_objects() in the SQL_DROP trigger. If the user
calls master_drop_all_shards while the table still exists, the schema
name and table name are ignored.
Author: Marco Slot
Reviewed-By: Andres Freund