---
id: 1d649e2c-9933-481f-8ce4-c083b4b14186
---

# MongoDB Efficiency of queries is degrading
---

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.

### Parameters
```shell
# Environment Variables

export COLLECTION="PLACEHOLDER"

export DATABASE="PLACEHOLDER"

export MONGODB_HOST="PLACEHOLDER"

export MONGODB_USER="PLACEHOLDER"

export MONGODB_PORT="PLACEHOLDER"

export MONGODB_PASSWORD="PLACEHOLDER"

```

## Debug

### First, let's check if the MongoDB instance is running
```shell
systemctl status mongodb
```

### If the instance is running, check the logs for any errors
```shell
journalctl -u mongodb --since "10 minutes ago"
```

### Check if the MongoDB queries are taking longer than usual (replace <database> and <collection> with the relevant names)
```shell
mongo ${DATABASE} --eval "db.${COLLECTION}.find().explain('executionStats')"
```

### Check the disk usage of the MongoDB instance
```shell
df -h /var/lib/mongodb
```

### Check the network connectivity between the MongoDB instance and the application server
```shell
ping ${MONGODB_HOST}
```

### Check the CPU and memory usage of the application server
```shell
top
```

## Repair

### Define variables
```shell
MONGODB_HOST=${MONGODB_HOST}

MONGODB_PORT=${MONGODB_PORT}

MONGODB_USER=${MONGODB_USER}

MONGODB_PASSWORD=${MONGODB_PASSWORD}
```

### Check for issues or errors in the MongoDB database
```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.runCommand({checkDatabase: 1})"
```

### Optimize indexes
```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.adminCommand({reIndex: ${COLLECTION}})"
```

### Run database repairs
```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.adminCommand({repairDatabase: 1})"
```


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.


This incident type refers to a sudden and abnormal drop in the SELECT query rate on a MySQL server. This can potentially cause disruption in the service and affect the user experience. The cause of the drop could be due to a variety of factors such as database issues, server overload, or network problems. It requires immediate attention and investigation to identify the root cause and resolve the issue to prevent further impact.


Unusual drop in SELECT query rate on MySQL server

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 involves an alert triggered when read latency is higher than usual for a MongoDB host. The alert is triggered when at least 100% of the average read latency values have been more than 2 deviations above the predicted values during the last 15 minutes. The incident requires monitoring and investigation to identify the root cause of the increased read latency and take appropriate actions to resolve it.


Read latency higher than average for MongoDB host.

This incident type refers to a situation where the write latency for a MongoDB database is higher than the average. This might cause delays in write operations and can negatively impact the performance of the system. The incident might be triggered by an alert that indicates that the write latency has exceeded a certain threshold, and it requires immediate attention from a software engineer to identify and resolve the underlying issue. The incident can be resolved by identifying and fixing the root cause of the latency issue, and ensuring that the system is functioning within acceptable performance parameters.


MongoDB Write Latency Higher Than Average

This incident type refers to an issue with high virtual memory usage in a MongoDB instance. It can lead to performance degradation or even service downtime. It requires immediate attention from the responsible team to investigate the root cause and take corrective measures to resolve the issue.


MongoDB virtual memory usage incident.

```shell
# Environment Variables

export COLLECTION="PLACEHOLDER"

export DATABASE="PLACEHOLDER"

export MONGODB_HOST="PLACEHOLDER"

export MONGODB_USER="PLACEHOLDER"

export MONGODB_PORT="PLACEHOLDER"

export MONGODB_PASSWORD="PLACEHOLDER"

```


### First, let's check if the MongoDB instance is running

```shell
systemctl status mongodb
```

### If the instance is running, check the logs for any errors

```shell
journalctl -u mongodb --since "10 minutes ago"
```

### Check if the MongoDB queries are taking longer than usual (replace <database> and <collection> with the relevant names)

```shell
mongo ${DATABASE} --eval "db.${COLLECTION}.find().explain('executionStats')"
```

### Check the disk usage of the MongoDB instance

```shell
df -h /var/lib/mongodb
```

### Check the network connectivity between the MongoDB instance and the application server

```shell
ping ${MONGODB_HOST}
```

### Check the CPU and memory usage of the application server

```shell
top
```


### Define variables

```shell
MONGODB_HOST=${MONGODB_HOST}

MONGODB_PORT=${MONGODB_PORT}

MONGODB_USER=${MONGODB_USER}

MONGODB_PASSWORD=${MONGODB_PASSWORD}
```

### Check for issues or errors in the MongoDB database

```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.runCommand({checkDatabase: 1})"
```

### Optimize indexes

```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.adminCommand({reIndex: ${COLLECTION}})"
```

### Run database repairs

```shell
mongo --host $MONGODB_HOST --port $MONGODB_PORT --username $MONGODB_USER --password $MONGODB_PASSWORD --eval "db.adminCommand({repairDatabase: 1})"
```


MongoDB Efficiency of queries is degrading

Overview

Parameters

Debug

First, let's check if the MongoDB instance is running

If the instance is running, check the logs for any errors

Check if the MongoDB queries are taking longer than usual (replace <database> and <collection> with the relevant names)

Check the disk usage of the MongoDB instance

Check the network connectivity between the MongoDB instance and the application server

Check the CPU and memory usage of the application server

Repair

Define variables

Check for issues or errors in the MongoDB database

Optimize indexes

Run database repairs

Learn more

Related Runbooks

Unusual drop in SELECT query rate on MySQL server

MySQL slow queries incident

Read latency higher than average for MongoDB host.

MongoDB Write Latency Higher Than Average

Support