---
id: 88cf1efc-616d-11ee-8c99-0242ac120002
---

# Slow Running Queries on Cassandra
---

This incident type relates to identifying slow running queries on the Cassandra database and determining the users responsible for running them. Slow queries can cause performance issues and impact the overall efficiency of the system. Identifying and troubleshooting slow queries is crucial for maintaining optimal performance and ensuring smooth operations of the database. The incident may require investigating the root cause of the slow queries, optimizing the database configuration and queries, and providing recommendations to mitigate future incidents.

### Parameters
```shell
export CASSANDRA_SERVER_IP="PLACEHOLDER"

export THRESHOLD_IN_MICROSECONDS="PLACEHOLDER"

export SESSION_ID="PLACEHOLDER"

export DATABASE_NAME="PLACEHOLDER"

```

## Debug

### 1. Connect to the Cassandra database
```shell
cqlsh ${CASSANDRA_SERVER_IP}
```

### 2. Enable tracing of slow queries
```shell
TRACING ON;
```

### 3. Execute a query to identify slow running queries
```shell
SELECT * FROM system_traces.sessions WHERE duration > ${THRESHOLD_IN_MICROSECONDS};
```

### 4. Identify the user running the slow query
```shell
SELECT user FROM system_traces.events WHERE session_id = ${SESSION_ID};
```

### 5. Kill the slow query by session ID
```shell
KILL ${SESSION_ID};
```

## Repair

### Identify the queries that are running slowly and analyze their execution plans to determine the root cause of the issue. This could involve examining the query syntax, identifying any poorly optimized queries, or checking for inefficient use of indexes.
```shell


#!/bin/bash



# Set the necessary environment variables

export CASSANDRA_HOME=${PATH_TO_CASSANDRA_HOME_DIRECTORY}

export CQLSH_HOST=${CASSANDRA_HOST}



# Identify the queries that are running slowly

slow_queries=$(cqlsh $CQLSH_HOST -e "SELECT * FROM system_traces.sessions WHERE duration > 10000 ALLOW FILTERING;")



# Analyze the execution plans of the slow queries

for query in $slow_queries; do

    execution_plan=$(cqlsh $CQLSH_HOST -e "SELECT * FROM system_traces.events WHERE session_id=$query;")

    echo "Slow query: $query"

    echo "Execution plan: $execution_plan"

done


```


This incident type relates to identifying slow running queries on the Cassandra database and determining the users responsible for running them. Slow queries can cause performance issues and impact the overall efficiency of the system. Identifying and troubleshooting slow queries is crucial for maintaining optimal performance and ensuring smooth operations of the database. The incident may require investigating the root cause of the slow queries, optimizing the database configuration and queries, and providing recommendations to mitigate future incidents.


A MySQL slow queries incident is when a MySQL server is experiencing slow queries. This can result in degraded performance and responsiveness of the system. It is important to resolve this incident quickly to minimize impact on users.


MySQL slow queries incident

This incident type refers to a situation where the MySQL database is experiencing a high level of threads running, which could indicate a performance issue. This may cause issues with the application that relies on the database, such as slow response times or even downtime. Resolving this incident typically involves investigating the root cause of the high thread count and optimizing the database configuration or query performance to reduce the load on the database.


MySQL high threads running incident.

This incident type describes an issue where the efficiency of queries in MongoDB is degrading. The incident may be triggered by an alert monitoring system that detects an anomaly in the performance of queries executed in the database. The incident may result in a decrease in system performance and may require the attention of a software engineer to troubleshoot and resolve the issue.


MongoDB Efficiency of queries is degrading

A MongoDB Replication Lag Incident occurs when there is a delay in the replication of data from the primary MongoDB instance to its secondary instances. This delay can cause data inconsistencies and affect the performance of the application. It is important to identify and resolve this incident as soon as possible to ensure that the application is functioning optimally.


MongoDB Replication Lag Incident

This incident type refers to a problem in a Cassandra cluster where the token range imbalances cause uneven distribution of data across the cluster. This can result in slower read and write performance that can impact the overall functionality of the system. Token range imbalances occur when the distribution of the tokens that define the ranges of data each node is responsible for is not evenly spread across the cluster. As a result, certain nodes may be responsible for a disproportionate amount of data, leading to performance issues and potential failure of the system.


Token Range Imbalances Causing Uneven Data Distribution and Performance Issues in Cassandra Cluster

```shell
export CASSANDRA_SERVER_IP="PLACEHOLDER"

export THRESHOLD_IN_MICROSECONDS="PLACEHOLDER"

export SESSION_ID="PLACEHOLDER"

export DATABASE_NAME="PLACEHOLDER"

```


### 1. Connect to the Cassandra database

```shell
cqlsh ${CASSANDRA_SERVER_IP}
```

### 2. Enable tracing of slow queries

```shell
TRACING ON;
```

### 3. Execute a query to identify slow running queries

```shell
SELECT * FROM system_traces.sessions WHERE duration > ${THRESHOLD_IN_MICROSECONDS};
```

### 4. Identify the user running the slow query

```shell
SELECT user FROM system_traces.events WHERE session_id = ${SESSION_ID};
```

### 5. Kill the slow query by session ID

```shell
KILL ${SESSION_ID};
```


### Identify the queries that are running slowly and analyze their execution plans to determine the root cause of the issue. This could involve examining the query syntax, identifying any poorly optimized queries, or checking for inefficient use of indexes.

```shell


#!/bin/bash



# Set the necessary environment variables

export CASSANDRA_HOME=${PATH_TO_CASSANDRA_HOME_DIRECTORY}

export CQLSH_HOST=${CASSANDRA_HOST}



# Identify the queries that are running slowly

slow_queries=$(cqlsh $CQLSH_HOST -e "SELECT * FROM system_traces.sessions WHERE duration > 10000 ALLOW FILTERING;")



# Analyze the execution plans of the slow queries

for query in $slow_queries; do

    execution_plan=$(cqlsh $CQLSH_HOST -e "SELECT * FROM system_traces.events WHERE session_id=$query;")

    echo "Slow query: $query"

    echo "Execution plan: $execution_plan"

done


```


Slow Running Queries on Cassandra

Overview

Parameters

Debug

1. Connect to the Cassandra database

2. Enable tracing of slow queries

3. Execute a query to identify slow running queries

4. Identify the user running the slow query

5. Kill the slow query by session ID

Repair

Identify the queries that are running slowly and analyze their execution plans to determine the root cause of the issue. This could involve examining the query syntax, identifying any poorly optimized queries, or checking for inefficient use of indexes.

Learn more

Related Runbooks

MySQL slow queries incident

MySQL high threads running incident.

MongoDB Efficiency of queries is degrading

MongoDB Replication Lag Incident

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