diff --git a/doc/questions.md b/doc/questions.md index be6eab0..7585bc7 100644 --- a/doc/questions.md +++ b/doc/questions.md @@ -28,3 +28,9 @@ It is therefore unlikely that `gh-ost` will support this behavior. Yes. TL;DR if running all on same replica/master, make sure to provide `--replica-server-id`. [Read more](cheatsheet.md#concurrent-migrations) # Why + +### Why Is the "Connect to Replica" mode preferred? + +To avoid placing extra load on the master. `gh-ost` connects as a replication client. Each additional replica adds some load to the master. + +To monitor replication lag from a replica. This makes the replication lag throttle, `--max-lag-millis`, more representative of the lag experienced by other replicas following the master (perhaps N levels deep in a tree of replicas). diff --git a/go/logic/inspect.go b/go/logic/inspect.go index 9b2da44..31184b0 100644 --- a/go/logic/inspect.go +++ b/go/logic/inspect.go @@ -622,8 +622,6 @@ func (this *Inspector) getCandidateUniqueKeys(tableName string) (uniqueKeys [](* GROUP BY TABLE_SCHEMA, TABLE_NAME, INDEX_NAME ) AS UNIQUES ON ( - COLUMNS.TABLE_SCHEMA = UNIQUES.TABLE_SCHEMA AND - COLUMNS.TABLE_NAME = UNIQUES.TABLE_NAME AND COLUMNS.COLUMN_NAME = UNIQUES.FIRST_COLUMN_NAME ) WHERE