Alert on a MySQL slow-query spike

Enterno.io Editorial Team

long_query_time = 1, slow_query_log enabled. You need to know when the slow-query rate per minute suddenly jumps (a deploy broke an index, ORM went N+1).

Stack: MySQL · slow_query_log · awk Tags: mysql, database, performance

Recipe

bash

#!/usr/bin/env bash
# Count slow queries logged in the last 60 seconds. Alert above THRESHOLD.
LOG="/var/log/mysql/mysql-slow.log"
THRESHOLD=${THRESHOLD:-20}

SINCE=$(date -u -d "1 minute ago" "+%Y-%m-%dT%H:%M")
COUNT=$(awk -v t="$SINCE" '
  /^# Time:/ { ts = substr($3 " " $4, 1, 16) }
  /^# Query_time/ && ts >= t { c++ }
  END { print c+0 }
' "$LOG")

if [ "$COUNT" -gt "$THRESHOLD" ]; then
  curl -X POST "$SLACK_WEBHOOK" \
    --data "{\"text\":\"MySQL: $COUNT slow queries in the last minute (threshold $THRESHOLD)\"}"
fi

Same thing in Enterno.io

A page-speed regression usually follows slow SQL. The PageSpeed checker + a Navigator-tier monitor with history surface the same signal at the TTFB level without needing slow-log access.

Set up Performance monitor → ← All recipes