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sql: implement buffer and scanBuffer planNodes #37050

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jordanlewis opened this issue Apr 23, 2019 · 0 comments · Fixed by #37137
Closed

sql: implement buffer and scanBuffer planNodes #37050

jordanlewis opened this issue Apr 23, 2019 · 0 comments · Fixed by #37137
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@yuzefovich
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A-sql-fks C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception)

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jordanlewis commented Apr 23, 2019 •
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A buffer planNode should consume input rows, write them to a buffer, and pass the rows through to the next node in the chain.

A scanBuffer planNode references a single buffer planNode and behaves like an iterator into that buffer. It doesn't live on the "main path" of a planNode tree - something else has to Next it to start it consuming from the buffer.

Together, these two nodes enable a couple of use cases:

  1. multiple references to a single WITH clause in a CTE, which is a known limitation: sql: multi-use common table expressions #21084
  2. optimizer-driven foreign key checks

For use case 2, you can imagine trees like the following making up a foreign key check, together (see issue #37053 for errorIfRows):

[valuesNode] -> [buffer 'x'] -> insertNode`
[scanBuffer 'x'] -> [lookup antijoin into reference table] -> [errorIfRows]
@jordanlewis jordanlewis added the C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) label Apr 23, 2019
@yuzefovich yuzefovich mentioned this issue Apr 25, 2019
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craig bot pushed a commit that referenced this issue May 15, 2019
@yuzefovich
Merge #37137
de3ac93 
37137: sql: add buffer and scanBuffer nodes r=yuzefovich a=yuzefovich

Adds bufferNode that consumes its input, stores all the rows in a
buffer, and then proceeds on passing the rows through. The buffer
can be iterated over multiple times using scanBuffer node that is
referencing a single bufferNode.

Fixes: #37050.

Release note: None

Co-authored-by: Yahor Yuzefovich <yahor@cockroachlabs.com>
@craig craig bot closed this as completed in #37137 May 15, 2019
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sql: add buffer and scanBuffer nodes yuzefovich/cockroach
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