PMM QAN MongoDB -- Explain is working randomly

Percona Monitoring and Management (PMM) PMM 2.x
,
1

Description:

The PMM QAN Explain is not working in most cases. Even for Find statements.
We have profile enabled fpr slow op only at systems lvl.
operationProfiling:
mode: slowOp
slowOpSampleRate: 0.1
slowOpThresholdMs: 200

The query is visible on the QAN dashboard and in system.profile collection. The details and Example tabs are working fine. However. explain is hanging for couple minutes and failed with the following error:

image
image2131×748 36 KB

FYI: for some queries we are able to pick up the explain plan. Same cluster , different db.

image
image2143×556 23.7 KB

Please, advise.

Thanks,

2

Hello, we are going to revisit QAN explain for MongoDB in 2.43.0.
Could you share queries that doesn’t work?

3

Hello,
Here is couple examples:
FIND scheduled-buy-rates Applied,Effective
FIND transactions DeliveryMethod.Payer.AlternativeId,Status,Updated

From Pmm the following is visible:
FIND scheduled-buy-rates Effective,Revisions.0

Same query in system.profile

command:{
        "find" : "scheduled-buy-rates",
        "filter" : {
                "Effective" : {
                        "$gte" : ISODate("0001-01-01T00:00:00Z"),
                        "$lte" : ISODate("2024-05-30T05:42:31Z")
                },
                "Applied" : null
        },
        "projection" : {
                "Revisions" : 0
        },
        "skip" : 0,
        "limit" : 2147483647,
        "readConcern" : {
                "level" : "majority"
        },
        "$db" : "pricing-qa",
        "$readPreference" : {
                "mode" : "primaryPreferred"
        },
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