How Do I Run A Compaction In Hive?

Is hive an ETL tool?

Extract, Transform, and Load (ETL) operations are used to prepare data and load it into a data destination.

Apache Hive on HDInsight can read in unstructured data, process the data as needed, and then load the data into a relational data warehouse for decision support systems..

What is the problem in having lots of small files in HDFS?

If you’re storing small files, then you probably have lots of them (otherwise you wouldn’t turn to Hadoop), and the problem is that HDFS can’t handle lots of files. Every file, directory and block in HDFS is represented as an object in the namenode’s memory, each of which occupies 150 bytes, as a rule of thumb.

How do you do compaction in hive?

Hive ACID supports these two types of compactions:Minor compaction: It takes a set of existing delta files and rewrites them to a single delta file per bucket.Major compaction: It takes one or more delta files and the base file for the bucket, and rewrites them into a new base file per bucket.

What is acid table in hive?

Apache Hive introduced transactions since version 0.13 to fully support ACID semantics on Hive table, including INSERT/UPDATE/DELETE/MERGE statements, streaming data ingestion, etc.

Can hive run without Hadoop?

Hadoop is like a core, and Hive need some library from it. Update This answer is out-of-date : with Hive on Spark it is no longer necessary to have hdfs support. Hive requires hdfs and map/reduce so you will need them. … But the gist of it is: hive needs hadoop and m/r so in some degree you will need to deal with it.

Does Hive support transaction?

Transactions in Hive are introduced in Hive 0.13, but they only partially fulfill the ACID properties like atomicity, consistency, durability, at the partition level. … Transactions are provided at the row-level in Hive 0.14. The different row-level transactions available in Hive 0.14 are as follows: Insert.

What is compaction in hive?

Compaction can be used to counter small file problems by consolidating small files. … In Hive small files are normally created when any one of the accompanying scenario happen. Number of files in a partition will be increased as frequent updates are made on the hive table.

What are the types of Compactions used by Hbase?

What are the types of Compactions?Bigger Hfile are created by combining smaller Hfiles.Hfile keeps the deleted file with them.Increases space in memory, useful to store more data.Merge sorting is used in process.

What is Hfile Hbase?

@InterfaceAudience.Private public class HFile extends Object. File format for hbase. A file of sorted key/value pairs.

Is HBase faster than Hive?

Hbase is faster when compared to Hive in fetching data. Hive is used to process structured data whereas HBase since it is schema-free, can process any type of data. Hbase is highly(horizontally) scalable when compared to Hive.

How do I reduce the number of files in Hive?

— File size (bytes) threshold — When the average output file size of a job is less than this number, — Hive will start an additional map-reduce job to merge the output files — into bigger files. This is only done for map-only jobs if hive. merge. mapfiles — is true, and for map-reduce jobs if hive.

How do I combine small files in HDFS?

In order to merge two or more files into one single file and store it in hdfs, you need to have a folder in the hdfs path containing the files that you want to merge. The merged_files folder need not be created manually. It is going to be created automatically to store your output when you are using the above command.

How does Hive handle small files?

Below 4 parameters determine if and how Hive does small file merge.merge. mapfiles — Merge small files at the end of a map-only job.merge. mapredfiles — Merge small files at the end of a map-reduce job.merge. size. per. … merge. smallfiles.

What is compaction in Hadoop?

Compaction is a process by which HBase cleans itself, and data locality is a solution to data not being available to Mapper. … That is reason why HBase tries to combine all HFiles into a large single HFile to reduce the maximum number of disk seeks needed for read. This process is known as compaction.

What is the use of Hive in Hadoop?

Apache Hive is a data warehouse software project built on top of Apache Hadoop for providing data query and analysis. Hive gives an SQL-like interface to query data stored in various databases and file systems that integrate with Hadoop.