---
id: 48f4005c-d497-4680-bf30-f6de3ac963a9
---

# MongoDB index corruption causing query performance issues.
---

This incident type refers to a problem in a MongoDB database where the index becomes corrupted, causing a significant decrease in query performance. This can result in slow query times, timeouts, or even complete failure to retrieve data. This issue can affect any application or service that relies on the affected MongoDB database. It is important to resolve this issue quickly to minimize the impact on end-users and ensure the reliability of the affected application or service.

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

export COLLECTION_NAME="PLACEHOLDER"

export BACKUP_DIRECTORY="PLACEHOLDER"

export DATABASE_NAME="PLACEHOLDER"

export DATABASE_HOST="PLACEHOLDER"
```

## Debug

### Check MongoDB version
```shell
mongod --version
```

### Check MongoDB log for any error messages
```shell
tail -f /var/log/mongodb/mongod.log
```

### Check MongoDB server status
```shell
mongo ${DB_NAME} --eval "printjson(db.serverStatus())"
```

### Check the status of all indexes on a specific collection
```shell
mongo ${DB_NAME} --eval "printjson(db.${COLLECTION_NAME}.getIndexes())"
```

### Repair corrupted indexes on a specific collection
```shell
mongo ${DB_NAME} --eval "db.${COLLECTION_NAME}.repair()"
```

## Repair

### Perform a complete backup of the database before attempting any remediation procedures.
```shell


#!/bin/bash



# Define variables

DB_HOST=${DATABASE_HOST}

DB_NAME=${DATABASE_NAME}

BACKUP_DIR=${BACKUP_DIRECTORY}



# Create backup directory if it doesn't exist

mkdir -p $BACKUP_DIR



# Create backup filename with timestamp

BACKUP_FILENAME="$BACKUP_DIR/$DB_NAME-$(date +%Y-%m-%d-%H-%M-%S).bson"



# Backup the database

mongodump --host $DB_HOST --db $DB_NAME --out $BACKUP_FILENAME



# Print success message

echo "Backup completed successfully: $BACKUP_FILENAME"


```

### If the index corruption is not easily fixable, consider rebuilding the indexes from scratch. This can be done using the "reindex" command in MongoDB.
```shell


#!/bin/bash



# Set variables

${DB_NAME}="${DATABASE_NAME}"

${COLLECTION_NAME}="${COLLECTION_NAME}"



# Stop the MongoDB service

sudo systemctl stop mongod.service



# Rebuild the indexes

mongo $DB_NAME --eval "db.$COLLECTION_NAME.reIndex()"



# Start the MongoDB service

sudo systemctl start mongod.service


```

This incident type refers to a problem in a MongoDB database where the index becomes corrupted, causing a significant decrease in query performance. This can result in slow query times, timeouts, or even complete failure to retrieve data. This issue can affect any application or service that relies on the affected MongoDB database. It is important to resolve this issue quickly to minimize the impact on end-users and ensure the reliability of the affected application or service.


```shell
export DB_NAME="PLACEHOLDER"

export COLLECTION_NAME="PLACEHOLDER"

export BACKUP_DIRECTORY="PLACEHOLDER"

export DATABASE_NAME="PLACEHOLDER"

export DATABASE_HOST="PLACEHOLDER"
```


### Check MongoDB version

```shell
mongod --version
```

### Check MongoDB log for any error messages

```shell
tail -f /var/log/mongodb/mongod.log
```

### Check MongoDB server status

```shell
mongo ${DB_NAME} --eval "printjson(db.serverStatus())"
```

### Check the status of all indexes on a specific collection

```shell
mongo ${DB_NAME} --eval "printjson(db.${COLLECTION_NAME}.getIndexes())"
```

### Repair corrupted indexes on a specific collection

```shell
mongo ${DB_NAME} --eval "db.${COLLECTION_NAME}.repair()"
```


### Perform a complete backup of the database before attempting any remediation procedures.

```shell


#!/bin/bash



# Define variables

DB_HOST=${DATABASE_HOST}

DB_NAME=${DATABASE_NAME}

BACKUP_DIR=${BACKUP_DIRECTORY}



# Create backup directory if it doesn't exist

mkdir -p $BACKUP_DIR



# Create backup filename with timestamp

BACKUP_FILENAME="$BACKUP_DIR/$DB_NAME-$(date +%Y-%m-%d-%H-%M-%S).bson"



# Backup the database

mongodump --host $DB_HOST --db $DB_NAME --out $BACKUP_FILENAME



# Print success message

echo "Backup completed successfully: $BACKUP_FILENAME"


```

### If the index corruption is not easily fixable, consider rebuilding the indexes from scratch. This can be done using the "reindex" command in MongoDB.

```shell


#!/bin/bash



# Set variables

${DB_NAME}="${DATABASE_NAME}"

${COLLECTION_NAME}="${COLLECTION_NAME}"



# Stop the MongoDB service

sudo systemctl stop mongod.service



# Rebuild the indexes

mongo $DB_NAME --eval "db.$COLLECTION_NAME.reIndex()"



# Start the MongoDB service

sudo systemctl start mongod.service


```


MongoDB index corruption causing query performance issues.

Overview

Parameters

Debug

Check MongoDB version

Check MongoDB log for any error messages

Check MongoDB server status

Check the status of all indexes on a specific collection

Repair corrupted indexes on a specific collection

Repair

Perform a complete backup of the database before attempting any remediation procedures.

If the index corruption is not easily fixable, consider rebuilding the indexes from scratch. This can be done using the "reindex" command in MongoDB.

Learn more

Related Runbooks

Support