I'm trying to use Prometheus and VictoriaMetrics to collect data and when configuring my server prometheus.yml there is one line:
scrape_interval: 15s # How frequently to scrape targets by default.
Does this mean my search result might be delayed by 15s?
Yes, this means that at worst, your metrics will arrive 15 seconds later. You can configure it to be faster.
<duration>: a duration matching the regular expression [0-9]+(ms|[smhdwy])
The above is from the Prometheus docs at: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#duration
Typically, think of it as Prometheus taking snapshots of what your (continuous) metrics look like (CPU used, no. of threads running etc.) instead of thinking of Prometheus as a place to collect discrete events.
When you are thinking of how long your alert will take to fire, or for the data to be visible, the scrape interval is a factor to keep in mind.
In the context of alerting, a good resource is this article: https://pracucci.com/prometheus-understanding-the-delays-on-alerting.html
It basically says that if your scrape interval is x time unit, and you only fire an alert if an expression is true for y time unit, then the delay could at worst be (x + y) time units.