kv: intentionally handle paginated responses in txnPipeliner

[nvanbenschoten]

See #108539 (comment).

This commit adds intentional handling to the txnPipeliner for the case where a response is paginated and not all QueryIntent requests were evaluated. Previously, we handled this case, but we logged a warning and had a comment that said it was unexpected.

The commit also adds a test for the case.

Epic: None
Release note: None

[cockroach-teamcity]

This change is 

[arulajmani]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @nvanbenschoten)

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pkg/kv/kvclient/kvcoord/txn_interceptor_pipeliner.go line 718 at r1 (raw file):

				tp.lockFootprint.insert(roachpb.Span{Key: qiReq.Key})
			} else {
				log.Warningf(ctx,

Is there any value in improving this log line and putting it behind a vmodule? Or keeping a count of the number of empty QueryIntentRresponses we got here, and maybe print that number out behind a vmodule?

Feel free to disregard if this feels unnecessary.

[nvanbenschoten]

TFTR!

bors r=arulajmani

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @arulajmani)

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pkg/kv/kvclient/kvcoord/txn_interceptor_pipeliner.go line 718 at r1 (raw file):

Previously, arulajmani (Arul Ajmani) wrote…

Is there any value in improving this log line and putting it behind a vmodule? Or keeping a count of the number of empty QueryIntentRresponses we got here, and maybe print that number out behind a vmodule?

Feel free to disregard if this feels unnecessary.

I was thinking that it may be valuable to keep the log.Warning for cases where we can detect that a batch response was not truncated, but doing so requires an extra iteration of the batch response to determine that above this loop, which did not seem worth it. Since this is now a known, expected condition, I think it's ok to keep without a log line. As we saw in #108539, the condition is rare, but workloads that do exercise this logic do so reliably and frequently (in that case, 656,000 times!).

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)