EXPLAIN - Hash Join
Description:
Build a hash table from the inner table, keyed by the join key. Then scan the outer table, checking if a corresponding value is present. If the hash table would exceed work_mem, this process needs to happen in several batches writing temporary files to disk, which becomes dramatically slower.
Important Fields:
- Filter
- Hash Cond
- Inner Unique
- Join Filter
- Join Type
- Rows Removed by Filter
- Rows Removed by Join Filter
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