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The salt column is added to the join key and the join can be performed as normal. However, now the skewed key can be processed across two workers which increases the performance.
Solution 3: Reorder inputs (BigQuery Transformation Pushdown only)
Skewed joins can cause a lot of shuffling and disk operation in BigQuery, which impacts query performance. BigQuery has some general recommendations when executing join operations on Skewed data, which can be found here Data skew.
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