Release candidate 123256

[jiangphcn]

git cherry-pick 75b6838
[release-candidate-123256 2ccfa79] Fix missing mango execution stats (part 1)
Author: Will Holley [email protected]
Date: Wed Jan 8 11:29:59 2020 +0000
3 files changed, 23 insertions(+), 6 deletions(-)

[ksnavely]

Peng Hui mentions this single commit should be sufficient on its own.

[jiangphcn]

yes, thanks @ksnavely

We need 2 builds to cover 55ef9f1 and 75b6838 separately so that we can support mixed situation during upgrade.

commit 55ef9f11ecacd5e78aff176b357fe8e7b3b619df
Author: Will Holley <[email protected]>
Date:   Tue Jan 7 13:40:32 2020 +0000

    Fix missing mango execution stats (part 2)

    The previous implementation of Mango execution stats relied on
    passing the docs_examined count from each shard to the coordinator
    in the view_row record. This failed to collect the count of
    documents read which weren't followed by a match (in a given shard).
    For example, if an index was scanned but no documents were matched,
    the docs_examined would be 0, when it should be equal to the number
    of documents in the index.

    This commit changes the implementation so that docs examined is passed
    only when each shard has completed its index scan.

    The work is split into 2 commits to support mixed-version cluster
    upgrades - the previous commit adds the message handlers only
    so can be safely rolled out without breaking in-flight requests.

commit 75b6838ee2dbb050337ad4c19a03ae5ba5d7b63f
Author: Will Holley <[email protected]>
Date:   Wed Jan 8 11:29:59 2020 +0000

    Fix missing mango execution stats (part 1)

    Adds message handlers to mango / all_docs / mrview fabric
    to recieve an execution_stats message.