CODEWITHSUNDEEP
google-bigquery
bignano
bignano

Reputation: 593

slow performance of join in BigQuery

My recent experience seems to point out that BigQuery with join performs much slower than that with only one table. Normally most queries will finish in no more than a few minutes. But the following join query takes more than 6000 seconds to finish with table1 having ~ 1 billion rows and table2 ~ 1 million rows.

SELECT a.*, coalesce(b.field4, a.field3) 
FROM `table1` a left outer join `table2` b
on a.field1 = b.field1 and a.field2 = b.field2

Just want to ask the community if this is expected or need further investigation?

Upvotes: 0

Views: 1350

Answers (1)

bignano
bignano

Reputation: 593

The solution is to specify a destination table. This will take down the total time to less than 200 seconds.

Upvotes: 0

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