What is sort merge bucket join?

SMB is a join performed on bucket tables that have the same sorted, bucket, and join condition columns. It reads data from both bucket tables and performs common joins (map and reduce triggered) on the bucket tables.

What is sort-merge join in hive?

What is Sort Merge Bucket Join in Hive? In Hive, while each mapper reads a bucket from the first table and the corresponding bucket from the second table, in SMB join. Basically, then we perform a merge sort join feature. Moreover, we mainly use it when there is no limit on file or partition or table join.

What is the condition to perform SMB join?

SMB join can best be used when the tables are large. In SMB join the columns are bucketed and sorted using the join columns. All tables should have the same number of buckets in SMB join. 2 Kudos.

What is Bucket map join?

In Hive, Bucket map join is used when the joining tables are large and are bucketed on the join column. In this kind of join, one table should have buckets in multiples of the number of buckets in another table.

What is MAP join and SMB join in Hive?

In SMB join in Hive, each mapper reads a bucket from the first table and the corresponding bucket from the second table and then a merge sort join is performed. Sort Merge Bucket (SMB) join in hive is mainly used as there is no limit on file or partition or table join.

What is Bucket join in Hive?

Is merge join faster than nested loop?

It is the fastest join operation in case of sorted tables. This is because it uses merge phase and sort phase, where, if sort is already previously done, then merge is the fastest operation.

What is Mapside join?

Map-side Join is similar to a join but all the task will be performed by the mapper alone. The Map-side Join will be mostly suitable for small tables to optimize the task.

What is Mapside combine?

What is skew join in Hive?

A skew join is used when there is a table with skew data in the joining column. A skew table is a table that is having values that are present in large numbers in the table compared to other data. Skew data is stored in a separate file while the rest of the data is stored in a separate file.