Merge branch 'master' into utf8-in-latin1

README.md

@@ -60,6 +60,7 @@ Also see:
 - [requirements and limitations](doc/requirements-and-limitations.md)
 - [what if?](doc/what-if.md)
 - [the fine print](doc/the-fine-print.md)
+- [Questions](https://github.com/github/gh-ost/issues?q=label%3Aquestion)
 
 ## What's in a name?
 

doc/requirements-and-limitations.md

@@ -28,6 +28,8 @@ The `SUPER` privilege is required for `STOP SLAVE`, `START SLAVE` operations. Th
 
 - MySQL 5.7 generated columns are not supported. They may be supported in the future.
 
+- MySQL 5.7 `JSON` columns are not supported. They are likely to be supported shortly.
+
 - The two _before_ & _after_ tables must share some `UNIQUE KEY`. Such key would be used by `gh-ost` to iterate the table.
   - As an example, if your table has a single `UNIQUE KEY` and no `PRIMARY KEY`, and you wish to replace it with a `PRIMARY KEY`, you will need two migrations: one to add the `PRIMARY KEY` (this migration will use the existing `UNIQUE KEY`), another to drop the now redundant `UNIQUE KEY` (this migration will use the `PRIMARY KEY`).
 
@@ -43,4 +45,7 @@ The `SUPER` privilege is required for `STOP SLAVE`, `START SLAVE` operations. Th
 - Multisource is not supported when migrating via replica. It _should_ work (but never tested) when connecting directly to master (`--allow-on-master`)
 
 - Master-master setup is only supported in active-passive setup. Active-active (where table is being written to on both masters concurrently) is unsupported. It may be supported in the future.
+
 - If you have en `enum` field as part of your migration key (typically the `PRIMARY KEY`), migration performance will be degraded and potentially bad. [Read more](https://github.com/github/gh-ost/pull/277#issuecomment-254811520)
+
+- Migrating a `FEDERATED` table is unsupported and is irrelevant to the problem `gh-ost` tackles.