VictoriaMetrics is a high-performance, cost-efficient time-series database compatible with the Prometheus ecosystem. Its MetricsQL query language extends PromQL, and its cluster architecture with vminsert, vmselect, and vmstorage enables horizontal scaling.
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A DevOps engineer needs a Prometheus-compatible time-series database that uses significantly less disk space. Which feature of VictoriaMetrics achieves this?
VictoriaMetrics uses a custom compression algorithm that typically achieves 10x better compression than Prometheus's TSDB. This is accomplished through delta-of-delta encoding and variable-length integer encoding optimized specifically for time-series patterns.
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What is MetricsQL in the context of VictoriaMetrics?
MetricsQL is VictoriaMetrics's query language that is backward-compatible with PromQL but adds extra functions like median_over_time(), outlier_iqr_over_time(), and improved rollup functions. Existing Prometheus queries work without modification.
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A team runs VictoriaMetrics in cluster mode. Which component is responsible for accepting write requests from Prometheus?
vminsert is the stateless write component that accepts incoming metrics from Prometheus, Telegraf, or other agents and distributes them across vmstorage nodes using consistent hashing. vmselect handles read queries, and vmauth handles authentication.
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Which VictoriaMetrics feature allows downsampling old data to reduce long-term storage costs?
vmalert recording rules can be used to pre-aggregate high-resolution data into lower-resolution metrics for long-term retention. VictoriaMetrics also supports native downsampling in cluster mode via the -downsampling.period flag to automatically reduce resolution of older samples.
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A developer configures VictoriaMetrics with -retentionPeriod=12. What does this setting control?
The -retentionPeriod flag in VictoriaMetrics defaults to months when given a plain integer. Setting -retentionPeriod=12 retains data for 12 months. You can suffix with d for days or w for weeks to override the default unit.