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https://issues.apache.org/jira/browse/KUDU-3427?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ashwani Raina reassigned KUDU-3427:
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Assignee: Ashwani Raina
> Add a metric for delta of snapshot vs current timestamp for scan-at-snapshot
> scans
> ----------------------------------------------------------------------------------
>
> Key: KUDU-3427
> URL: https://issues.apache.org/jira/browse/KUDU-3427
> Project: Kudu
> Issue Type: Improvement
> Components: tserver
> Reporter: Alexey Serbin
> Assignee: Ashwani Raina
> Priority: Major
> Labels: operability, supportability
>
> Currently, the setting for the {{\-\-tablet_history_max_age_sec}} is set to
> quite arbitrary value of 60 * 60 * 24 * 7 seconds (7 days). Keeping a lot
> of data in UNDO deltas for longer than necessary means using IO throughput,
> CPU cycles, and memory during various types of background maintenance jobs to
> process data which no longer needed. However, as of Kudu 1.16.0 version,
> there isn't a simple way to tell whether the current setting of
> {{\-\-tablet_history_max_age_sec}} is appropriate for the workload running on
> a Kudu cluster. An operator interested in optimizing the amount of tablet
> history stored has no visibility on what might be the optimal value for the
> {{\-\-tablet_history_max_age_sec}} based on the workloads run against the
> cluster.
> It would be great to add a per-tablet metric (a histogram?) to accumulate
> stats on the difference of snapshots used for scan operations in
> READ_AT_SNAPSHOT and READ_YOUR_WRITES mode vs current timestamp.
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