The HiveStreamingConnection is highly optimized for write throughput (Delta Streaming Optimizations) and as a result the delta files generated by hive Hive streaming ingest has have many of the orc ORC features disabled (dictionary encoding, indexes, compression, etc.) to facilitate high throughput writes. When the compactor kicks in, these delta files gets get rewritten into read- and storage-optimized orc ORC format (enable dictionary encoding, indexes and compression). So it is recommended to configure the compactor more aggressively/frequently (refer to Compactor) to generate compacted and optimized orc ORC files.
Notes about the HiveConf Object
- hive.txn.manager = org.apache.hadoop.hive.ql.lockmgr.DbTxnManager
- hive.support.concurrency = true
- hive.metastore.execute.setugi = true
- hive.exec.dynamic.partition.mode = nonstrict
- hive.exec.orc.delta.streaming.optimizations.enabled = true
- hive.metastore.client.cache.enabled = false
I/O – Writing Data
These classes and interfaces provide support for writing the data to Hive within a transaction.
- Modify input record: This may involve dropping fields from input data if they don’t have corresponding table columns, adding nulls in case of missing fields for certain columns, and adding __HIVE_DEFAULT_PARTITION__ if partition column value is null or empty. Dynamically creating partitions requires understanding of incoming data format to extract last columns to extract partition values.
- Encode modified record: The encoding involves serialization using an appropriate Hive SerDe.
- For bucketed tables, extract bucket column values from the record to identify the bucket where the record belongs.
- For partitioned tables, in dynamic partitioning mode, extract the partition column values from last N columns (where N is number of partitions) of the record to identify the partition where the record belongs.
- Write encoded record to Hive using the AcidOutputFormat's record updater for the appropriate bucket.