distsql: distributed hash join

[irfansharif]

Implementation of the HashJoinerSpec with support for INNER JOIN,
FULL OUTER, LEFT OUTER and RIGHT OUTER joins.
Implementation is the standard hash join algorithm, we distinctly use the
left row source/stream to construct our 'seen' hash map/set and use
the right row source/stream to probe in.

No strong opinions of some of the names chosen here (see bucket/
buckets), open to suggestions.
Part of #7587.

cc @RaduBerinde

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This change is

[RaduBerinde]

Wow, you are very fast!

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Review status: 0 of 8 files reviewed at latest revision, 2 unresolved discussions, all commit checks successful.

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pkg/sql/distsql/hashjoiner.go, line 35 at r2 (raw file):

}

// TODO(irfansharif): It's trivial to use the grace hash join algorithm by using

I would remove this comment - this is exactly the plan, and we don't need to do anything extra in this layer to support it - it's up to the physical planner to set it up. See https://github.com/cockroachdb/cockroach/blob/master/docs/RFCS/distributed_sql.md#stream-joins

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pkg/sql/distsql/processors.proto, line 192 at r2 (raw file):

// right row (i+1).
message HashJoinerSpec {
  // The join constraints certain columns from the left stream to equal

This comment applies to both left_eq_columns, right_eq_columns. We should keep them next to each other.

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Comments from Reviewable

[irfansharif]

hahaha, thank you! pulling in once CI is green.

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Review status: 0 of 8 files reviewed at latest revision, 2 unresolved discussions, some commit checks pending.

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pkg/sql/distsql/hashjoiner.go, line 35 at r2 (raw file):

Previously, RaduBerinde wrote…

I would remove this comment - this is exactly the plan, and we don't need to do anything extra in this layer to support it - it's up to the physical planner to set it up. See https://github.com/cockroachdb/cockroach/blob/master/docs/RFCS/distributed_sql.md#stream-joins

oops, Done.

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pkg/sql/distsql/processors.proto, line 192 at r2 (raw file):

Previously, RaduBerinde wrote…

This comment applies to both left_eq_columns, right_eq_columns. We should keep them next to each other.

Done.

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Comments from Reviewable