Alexander Kolbasov created HIVE-18940:
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Summary: Hive notifications serialize all write DDL operations
Key: HIVE-18940
URL: https://issues.apache.org/jira/browse/HIVE-18940
Project: Hive
Issue Type: Bug
Components: Metastore
Affects Versions: 3.0.0
Reporter: Alexander Kolbasov
The implementation of DbNotificationListener uses a single row to store current
notification ID and uses {{SELECT FOR UPDATE}} to lock the row. This serializes
all write DDL operations which isn't good.
We should consider using database auto-increment for notification ID instead.
Especially on mMySQL/innoDb it is supported natively with relatively
light-weight locking.
This creates potential issue for consumers though because such IDs may have
holes. There are two types of holes - transient hole for a transaction which
have not committed yet and will be committed shortly and permanent holes for
transactions that fail. Consumers need to deal with it. It may be useful to add
DB-generated timestamp as well to assist in recovery from holes.
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