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Scheduling group

As explained in ScyllaDB in Action

A scheduling group is a Seastar execution construct that groups scheduled tasks and manages their workload allocation.

A scheduling group is a Seastar execution construct that schedules tasks and allocates workloads within a shard. ScyllaDB reports latency metrics separately for each group. section 11.1.2

Calculating read latency

A read-latency metric may contain separate values for scheduling groups. The statement group represents query execution, while the streaming group represents maintenance work such as node bootstrapping or materialized-view construction. Sum the labeled latency values and divide by the summed request counts to calculate overall read latency. section 11.1.2

How ScyllaDB in Action covers it

How deep it goes
Defines task scheduling and shard workload allocation, then demonstrates metric aggregation without descending into Seastar internals.
Examples
Uses statement and streaming groups plus PromQL sums to calculate aggregate read latency.
What you can do after
Diagnose read latency by filtering scheduling-group labels and aggregating latency and request-count metrics.
How it connects
Connects scheduling groups with Seastar, shards, Prometheus, PromQL, latency metrics, and maintenance operations.
Cover of ScyllaDB in Action
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of ScyllaDB in Action. The section links point to the parts of the book it draws on.