> ## Documentation Index
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# Top 10 Slowest Queries (digest), MariaDB

> Top 10 Slowest Queries (digest) for MariaDB instances. Tracked live in Vortex IQ Nerve Centre. How to read it, why it matters, and how to act on it.

**Card class:** [Non-Hero](/nerve-centre/overview#card-classes-explained)  •  **Category:** [Performance](/nerve-centre/connectors#connectors-by-type)

## At a glance

> **Top 10 Slowest Queries (digest)** ranks the ten worst-performing query patterns on your MariaDB instance over the last 24 hours, grouped by normalised digest (the query shape with literals stripped). It is the single most actionable performance card for a DBA: it tells you exactly which statements to optimise first. Each row carries the digest text, total execution time, average latency, and call count, so you can tell the difference between a slow query run once and a fast query run a million times.

|                    |                                                                                                                                                                                                                                |
| ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **What it tracks** | The ten query digests with the highest aggregate cost on the selected instance, broken down by row. A digest is the normalised query shape, so `SELECT * FROM orders WHERE id = 42` and `... id = 99` collapse into one entry. |
| **Data source**    | `performance_schema.events_statements_summary_by_digest`, optionally enriched by the slow query log when `slow_query_log = ON` and `long_query_time` is set.                                                                   |
| **Time window**    | `24h` rolling.                                                                                                                                                                                                                 |
| **Alert trigger**  | None. This card is diagnostic, not alerting; pair it with [Slow-Query Rate %](/nerve-centre/kpi-cards/mariadb/slow-query-rate) for the threshold view.                                                                         |
| **Roles**          | engineering, operations                                                                                                                                                                                                        |

## What it tracks

The card reads from `performance_schema.events_statements_summary_by_digest`, the Performance Schema table MariaDB maintains in memory for every distinct query shape it has seen since the last counter reset. For each digest it surfaces `SUM_TIMER_WAIT` (total time spent), `COUNT_STAR` (how many times the pattern ran), `AVG_TIMER_WAIT` (mean latency), and `SUM_ROWS_EXAMINED` (the scan cost). Vortex IQ ranks by total time spent over the trailing 24 hours, because that is the metric that best correlates with where tuning effort pays off: a query that takes 80ms but runs 400,000 times a day costs the engine far more wall-clock than a 12-second report that runs twice. Use the digest text to locate the statement in your ORM or stored procedures, then reach for `EXPLAIN` and index analysis. A row that scans millions of rows to return a handful is almost always a missing or unused index.

## Reconciling against the source

To verify against MariaDB's own tooling, run `SELECT DIGEST_TEXT, COUNT_STAR, SUM_TIMER_WAIT/1000000000000 AS total_sec, AVG_TIMER_WAIT/1000000000 AS avg_ms FROM performance_schema.events_statements_summary_by_digest ORDER BY SUM_TIMER_WAIT DESC LIMIT 10;`. On managed services use the equivalent: AWS RDS / SkySQL Performance Insights, or `pt-query-digest` against the slow log. Note that Performance Schema counters reset on restart, so a freshly restarted node shows a shorter window than Vortex IQ's full 24h.

***

### Tracked live in Vortex IQ Nerve Centre

*Top 10 Slowest Queries (digest)* is one of hundreds of KPI pulses Vortex IQ tracks across MariaDB and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English.

[Start for free](https://app.vortexiq.ai/login) or [book a demo](https://www.vortexiq.ai/contact-us) to see this metric running on your own data.