Metrics related to vreplication functionality

VReplication exports several metrics using the expvars interface. These are available at the debug/vars endpoint of vttablet’s http status pages. More details here

Target Metrics #

VReplicationCopyLoopCount, VReplicationCopyLoopCountTotal #

During the copy phase we run one loop of bulk copy for approximately an hour at a time before running catchup. VReplicationCopyLoopCount counts the number of times this loop has run for each stream and VReplicationCopyLoopCountTotal the total across all streams.

VReplicationCopyRowCount, VReplicationCopyRowCountTotal #

VReplicationCopyRowCount counts the number of rows copied during the copy phase per stream and VReplicationCopyRowCountTotal the total across all streams.

VReplicationErrors #

VReplicationErrors counts the number of times errors occurred during vreplication. Errors are keyed with the type of error.

VReplicationHeartbeat #

VReplicationHeartbeat records, for each stream, the timestamp sent by the last heartbeat event for that stream.

VReplicationMessages #

VReplicationMessages contains a stack of the last N (currently 3) messages of a vreplication stream.

VReplicationMessages #

VReplicationMessages contains a stack of the last N (currently 3) messages of a vreplication stream.

VReplicationPhaseTimings, VReplicationPhaseTimingsCounts, VReplicationPhaseTimingsTotal #

This metric relates to the times each phase is run during the lifetime of a stream. VReplicationPhaseTimings counts the total time taken by the runs, VReplicationPhaseTimingsCounts the number of runs and VReplicationPhaseTimingsTotals the total runs across all streams.

VReplicationQPS #

VReplicationQPS is a list of QPS values for each loop of each phase of the workflow.

VReplicationQueryCount, VReplicationQueryCountTotal #

VReplicationQueryCount is the total number of queries in each phase of a workflow. VReplicationQueryCountTotal is the total queries across all phases and workflows.

VReplicationSecondsBehindMaster, VReplicationSecondsBehindMasterMax, VReplicationSecondsBehindMasterTotal #

These metrics show the replication lag of the target stream with respect to the source stream. VReplicationSecondsBehindMaster shows the current replication lag and VReplicationSecondsBehindMasterMax has the maximum lag in this stream. Note that these values are only valid during the replication phase of a workflow.

VReplicationSource #

Shows the keyspace and shard of the source from which this target stream is replicating

VReplicationSourceTablet #

Shows the tablet from which this stream is currently replicating

VReplicationStreamCount #

The number of streams running on this target

VReplicationStreamState #

This shows the state of each stream.

Source Metrics #

VStreamPacketSize #

The value of the vstream_packet_size flag specified for this tablet

VStreamerErrors #

The number of errors per category across workflows

VStreamersEndedWithErrors #

The total number of errors that caused a stream to stall

VStreamerEventsStreamed #

The total number of events streamed by this vttablet across all workflows

VStreamerNumPackets #

The total number of packets sent by this vttablet across all workflows

VStreamersCreated #

The total number of vstreamer created during the lifetime of this tablet

Example #

A snippet from tablet 200 from the local example after running the MoveTables step

"VReplicationCopyLoopCount": {"commerce.0.commerce2customer.1": 2},
"VReplicationCopyLoopCountTotal": 2,
"VReplicationCopyRowCount": {"commerce.0.commerce2customer.1": 10},
"VReplicationCopyRowCountTotal": 10,
"VReplicationErrors": {},
"VReplicationHeartbeat": {"commerce.0.commerce2customer.1": 1618681048},
"VReplicationMessages": {"1": "2021-04-17T19:36:13.003858838+02:00:Picked source tablet: cell:\"zone1\" uid:100 "},
"VReplicationPhaseTimings": {"commerce.0.commerce2customer.1.catchup": 948, "commerce.0.commerce2customer.1.fastforward": 555, "commerce.0.commerce2customer.1.copy": 615},
"VReplicationPhaseTimingsCounts": {"commerce.0.commerce2customer.1.fastforward": 2, "commerce.0.commerce2customer.1.copy": 2, "commerce.0.commerce2customer.1.All": 6, "commerce.0.commerce2customer.1.catchup": 2},
"VReplicationPhaseTimingsTotal": 2118,
"VReplicationQPS": {"All":[7.2,1,1.2,1,1.2,1,1.2,1.2,1,1.2,1,1.2,1,1.2,1],"Query":[6.6,1,1.2,1,1.2,1,1.2,1.2,1,1.2,1,1.2,1,1.2,1],"Transaction":[0.6,0,0,0,0,0,0,0,0,0,0,0,0,0,0]},
"VReplicationQueryCount": {"commerce.0.commerce2customer.1.copy": 2},
"VReplicationQueryCountTotal": 2,
"VReplicationSecondsBehindMaster": {"commerce.0.commerce2customer.1": 0},
"VReplicationSecondsBehindMasterMax": 0,
"VReplicationSecondsBehindMasterTotal": 0,
"VReplicationSource": {"1": "commerce/0"},
"VReplicationSourceTablet": {"1": "cell:\"zone1\" uid:100 "},
"VReplicationStreamCount": 1,
"VReplicationStreamState": {"commerce2customer.1": "Running"},
"VStreamPacketSize": 250000,
"VStreamerErrors": {"Catchup": 0, "Copy": 0, "Send": 0, "TablePlan": 0},
"VStreamerEventsStreamed": 0,
"VStreamerNumPackets": 0,
"VStreamerPhaseTiming": {"TotalCount":0,"TotalTime":0,"Histograms":{}},
"VStreamersCreated": 0,
"VStreamersEndedWithErrors": 0,