Re: Add memory/disk usage for WindowAgg nodes in EXPLAIN

> 1. It's probably a minor detail, but in show_recursive_union_info(), I
> don't think the tuplestores can ever be NULL.
>
> + if (working_table != NULL)
> + tuplestore_get_stats(working_table, &tempStorageType, &tempSpaceUsed);
> +
> + if (intermediate_table != NULL)
> + tuplestore_get_stats(intermediate_table, &maxStorageType, &maxSpaceUsed);
>
> I added the NULL tests for the Materialize case as the tuplestore is
> created in ExecMaterial() rather than ExecInitMaterial(). For the two
> tuplestorestates above, they're both created in
> ExecInitRecursiveUnion().

You are right. Also I checked other Exec* in nodeRecursiveunion.c and
did not find any place where working_table and intermediate_table are
set to NULL.

> 2. I imagined you'd always do maxSpaceUsed += tempSpaceUsed; or
> maxSpaceUsedKB = BYTES_TO_KILOBYTES(maxSpaceUsed + tempSpaceUsed);
>
> + if (tempSpaceUsed > maxSpaceUsed)
> + {
> + maxStorageType = tempStorageType;
> + maxSpaceUsed = tempSpaceUsed;
> + }
>
> Why do you think the the space used by the smaller tuplestore should
> be ignored in the storage size output?

I thought about the case when the two tuplestores have different
storage types. But I remember that we already use disk storage type
even if the storage type was changed from disk to memory[1]. So
probably we don't need to much worry about the storage kind difference
in the two tuplestores.

Attached patch fixes 1 & 2.

[1] https://www.postgresql.org/message-id/CAExHW5vRPRLvsZYLmNGcDLkPDWDHXGSWYjox-to-OsCVFETd3w%40mail.gmail.com

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
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