Hi, I'm using Hive Streaming API to write data to hive. Recently I looked into the metastore db I found that the tables of COMPLETED_TXN_COMPONENTS, TXNS, TXN_COMPONENTS took large of data size, especially COMPLETED_TXN_COMPONENTS took almost 3GB.
I'm concerning the increasing sizes of these tables, could anyone tole me what are they about?
I looked into the data in COMPLETED_TXN_COMPONENTS, they don't seem meanful rather then records of used transaction id.
1. Is it safe to clear these tables?
2. If I migrate data from one Hive cluster to another one, do I have to keep these 3 tables identical with the metastore db in the new cluster?