[Postgres-xc-developers] INSERT SELECT patch

[Mason S. <mas...@en...>]

I am sending this out to allow for feedback.

This patch adds support for INSERT SELECT (including "multi-step" queries).

This is done by utilizing COPY. We query the data nodes with the tuples
being sent to the Coordinator. These are then converted into COPY lines
and sent back down to the appropriate nodes. (Long term when we add
data node to data node communication, these can be sent directly).

We also optimize for the case when the SELECT is single-step, the
destination table is partitioned, the input column value comes from
the partition column of the source, and there are no limit or offset
clauses. In this case, we just pass down the INSERT SELECT to the data
nodes.

There is one kluge here in that I added a static variable for the
copy state. I did this to avoid having to move the CopyState definition
to a header file (for usage in execMain.c), in order to make merging
with vanilla PostgreSQL easier.

-- 
Mason Sharp
EnterpriseDB Corporation
The Enterprise Postgres Company


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