pt-query-digest query_review.first_seen vs. query_review_history.ts_min

[Jacky Shu]

Hi,

When checking the result of pt-query_digest, I noticed column query_review.first_seen and query_review_history.ts_min always have the same value.

Do they actually have any difference?

Thanks.

[Gavin Towey]

Hi Jacky,

They can have the same value, but not always.  The query_review table keeps unique instances of each query, but the query_review_history can have multiple entries for each query fingerprint.  The fields ts_min and ts_max are the statistics aggregated for that query in that particular duration of time.  I'm not sure what the original author intended with the abbreviation ts_, but I think of it as "time slice" or "time series."  

In the query_review table, there's only one entry per unique query fingerprint, and the values for first_seen and last_seen are updated with the smallest value of ts_min for any record in the history table, and last_seen has the highest value of any ts_max value.

Regards,

Gavin Towey

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[Jacky Shu]

Thanks Gavin.

Guess I should have used a query to check whether they have same value!

Gavin Towey

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[Jacky Shu]

Hi Gavin,

Sorry have to ask you again, what is the meaning of  query_review_history.ts_cnt column?

I thought it was how many times a query ran, but it was wrong.

Thanks

[Gavin Towey]

ts_cnt is indeed the count of instances of that query found in that time interval.  What are you seeing that makes it look like that isn't true for you?

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[Jacky Shu]

Ooops, I forgot the counting was based on " in that time interval". now it started to make sense.

Thanks again.

Thanks

Thanks Gavin.

Gavin Towey

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