Re: Is Union Queries run in Parallel form or not.

[Azeem Haider]

You mean it depend on Machine. If it support multiple-processors then it automatically run in parallel. If it is single processor then it run one by one.

I test it on Core i5 but it seems it's not run in parallel. I think core i5 support at least two physical multi processor. It should need to run in parallel
form.

Here is what I found when I run query with explain

id select_type table partitions type possible_keys key key_len ref rows filtered Extra
------------------------------------------------------------------------------------------------------------------------------------------------------
1 PRIMARY table1 NULL ALL NULL NULL NULL NULL 122882 100.00 NULL
2 UNION table2 NULL ALL NULL NULL NULL NULL 122882 100.00 NULL
NULL UNION RESULT <union1,2> NULL ALL NULL NULL NULL NULL NULL NULL Using temporary


Actually I need to work on Google Cloud SQL. is it support UNION queries in parallel form ?