Ignore internal tables in MoveTables and Reshard Workflows

[mattlord]

Description

We need to ignore internal operation tables (e.g. for OnlineDDL processing) in MoveTables and Reshard workflows. We need to do this both when processing the -tables command-line flags and when processing SchemaDefinition structures that we get from the database.

I also got rid of the logging messages for when these internal tables are seen and ignored/skipped as I don't think that they are helpful to the end user.

You can see a simple Reshard demonstration and test here

These are using the docker_local container.

Before (main):

$ make docker_local && ./docker/local/run.sh
./201_customer_tablets.sh ; ./202_move_tables.sh ; sleep 10; ./203_switch_reads.sh ; ./204_switch_writes.sh ; ./205_clean_commerce.sh ; ./301_customer_sharded.sh ; ./302_new_shards.sh; sleep 5; mysql customer -e "create table _vt_PURGE_1f9194b43b2011eb8a0104ed332e05c2_20201210194431(id int, val varbinary(128), primary key(id))"; ./303_reshard.sh ; sleep 5; mysql customer/-80 -e "show tables"
...
+-----------------------------------------------------------+
| Tables_in_vt_customer                                     |
+-----------------------------------------------------------+
| _vt_PURGE_1f9194b43b2011eb8a0104ed332e05c2_20201210194431 |
| corder                                                    |
| customer                                                  |
+-----------------------------------------------------------+

After (this branch):

$ make docker_local && ./docker/local/run.sh
./201_customer_tablets.sh ; ./202_move_tables.sh ; sleep 10; ./203_switch_reads.sh ; ./204_switch_writes.sh ; ./205_clean_commerce.sh ; ./301_customer_sharded.sh ; ./302_new_shards.sh; sleep 5; mysql customer -e "create table _vt_PURGE_1f9194b43b2011eb8a0104ed332e05c2_20201210194431(id int, val varbinary(128), primary key(id))"; ./303_reshard.sh ; sleep 5; mysql customer/-80 -e "show tables"
...
+-----------------------+
| Tables_in_vt_customer |
+-----------------------+
| corder                |
| customer              |
+-----------------------+

Related Issue(s)

Follow-up to: #8992
Fixes: #9577, #9576

Checklist

• Should this PR be backported? No
• Tests were added
• Documentation is not required (users should not even be aware of these tables)

[mattlord]

@shlomi-noach could you please offer some insights/input here if you have time? You may be aware of potential problems in eliding the internal tables at the mysqlctl.GetSchema layer. If so, I'll have to find more locations to explicitly ignore these internal tables (Reshard still fails w/o that and will have to find an alternative fix).

[mattlord]

@shlomi-noach could you please offer some insights/input here if you have time? You may be aware of potential problems in eliding the internal tables at the mysqlctl.GetSchema layer. If so, I'll have to find more locations to explicitly ignore these internal tables (Reshard still fails w/o that and will have to find an alternative fix).

The failed tests seem to be telling me it is a problem. 🙂 I'll abandon that approach, at least for now.

[rohit-nayak-ps]

lgtm

[mattlord]

Thank you, @shlomi-noach and @rohit-nayak-ps! I've addressed those comments here: a5638eb