问题
I am testing out NiFi to replace our current ingestion setup which imports data from multiple MySQL shards of a table and store it in HDFS.
I am using GenerateTableFetch and ExecuteSQL to achieve this.
Each incoming flow file will have a database.name attribute which is being used by DBCPConnectionPoolLookup to select the relevant shard.
Issue is that, let's say I have 2 shards to pull data from, shard_1 and shard_2 for table accounts and also I have updated_at as Maximum Value Columns, it is not storing state for the for the table@updated_at per shard. There is only 1 entry per table in state.
When I check in Data Provenance, I see the shard_2 flowfile file getting dropped without being passed to ExecuteSQL. And my guess is it's because shard_1 query gets executed first and then when shard_2 query comes, it's records are checked against shard_1's updated_at and since it returns empty, it drops the file.
Has anyone faced this issue? Or am I missing something?
回答1:
The ability to choose different databases via DBCPConnectionPoolLookup was added after the scheme to store state in the database fetch processors (QueryDatabaseTable, GenerateTableFetch, e.g.). Also, getting the database name differs between RDBMS drivers, it might be in the DatabaseMetaData or ResultSetMetaData, possibly in getCatalog() or getSchema() or neither.
I have written NIFI-5590 to cover this improvement.
来源：https://stackoverflow.com/questions/52239603/nifi-generatetablefetch-does-not-store-state-per-database-name