What is a hash join in SQL?

1.	What is a hash join in SQL?
Answer» Just like any other join, the hash join requires two inputs, which are the probe input (inner table) and the build input (outer table). A hash join involves the use of a hash table to identify rows matching between two tables. The hash join is the option when no other join is preferred (possibly due to the absence of sorting or indexing etc). Hash joins are best when joining large data sets that are unsorted and non-indexed.

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