Previously setting `enable_order_by_all` distinguished for ORDER BY ALL
whether we should sort by column 'all' (if given in the SELECT clause)
or by all columns. The actual behavior was not always intuitive.
Now, we throw unconditionally an exception which also simplifies the
handling a bit. Only an edge case is affected and if users really want
to run ORDER BY ALL on a column names 'all', they can alias it.
One binlog connection for many databases.
Suggesting to disable this feature by default for now. It should be explicitly enabled by SETTINGS use_binlog_client=1.
But if you would permanently enable it in MaterializedMySQLSettings, it should keep old behavior and all tests should pass too.
1. Introduced `IBinlog` and its impl to read the binlog events from socket - `BinlogFromSocket`, or file - `BinlogFromFile`. Based on prev impl of `EventBase` and the same old binlog parsers. It fully keeps BC with old version. Fixed `./check-mysql-binlog` to test new impl.
2. Introduced `BinlogEventsDispatcher`, it reads the event from the source `IBinlog` and sends it to currently attached `IBinlog` instances.
3. Introduced `BinlogClient`, which is used to group a list of `BinlogEventsDispatcher` by MySQL binlog connection which is defined by `user:password@host:port`. All dispatchers with the same binlog position should be merged to one.
4. Introduced `BinlogClientFactory`, which is a singleton and it is used to track all binlogs created over the instance.
5. Introduced `use_binlog_client` setting to `MaterializedMySQL`, which forces to reuse a `BinlogClient` if it already exists in `BinlogClientCatalog` or create new one. By default, it is disabled.
6. Introduced `max_bytes_in_binlog_queue` setting to define the limit of bytes in binlog's queue of events. If bytes in the queue increases this limit, `BinlogEventsDispatcher` will stop reading new events from source `IBinlog` until the space for new events will be freed.
7. Introduced `max_milliseconds_to_wait_in_binlog_queue` setting to define max ms to wait when the max bytes exceeded.
7. Introduced `max_milliseconds_to_wait_in_binlog_queue` setting to define max ms to wait when the max bytes exceeded.
8. Introduced `max_bytes_in_binlog_dispatcher_buffer` setting to define max bytes in the binlog dispatcher's buffer before it is flushed to attached binlogs.
9. Introduced `max_flush_milliseconds_in_binlog_dispatcher` setting to define max milliseconds in the binlog dispatcher's buffer to wait before it is flushed to attached binlogs.
10. Introduced `system.mysql_binlogs` system table, which shows a list of active binlogs.
11. Introduced `UnparsedRowsEvent` and `MYSQL_UNPARSED_ROWS_EVENT`, which defines that an event is not parsed and should be explicitly parsed later.
12. Fixed bug when not possible to apply DDL since syntax error or unsupported SQL.
@larspars is the author of following:
`GTIDSets::contains()`
`ReplicationHelper`
`shouldReconnectOnException()`
