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Description

MongoDB Error 262, 'Exceeded Time Limit', indicates that a database operation (such as a query, aggregation, or write) failed to complete within its configured or default time limit. This typically occurs when operations are complex, involve large datasets, or encounter performance bottlenecks.

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Error Message

Exceeded Time Limit

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Known Causes

4 known causes

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Complex or Inefficient Operations

Queries, aggregations, or write operations that are computationally intensive or process large volumes of data can exceed the default or configured time limits.

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Missing or Ineffective Indexes

Without appropriate indexes, MongoDB may perform full collection scans, significantly increasing query execution time beyond the set limits.

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Network Latency or Congestion

High network latency between the application and the MongoDB server, or network congestion, can delay operations and cause them to time out.

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Server Resource Bottlenecks

Insufficient CPU, memory, or disk I/O on the MongoDB server can slow down operations, preventing them from completing within the specified time.

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Solutions

3 solutions available

1. Optimize Slow Queries medium

Identify and improve long-running queries that are exceeding the operation time limit.

1

Enable the slow query log to capture queries exceeding a specified threshold.

mongod --setParameter slowms=100 --logpath /var/log/mongodb/mongod.log

2

Analyze the slow query log for queries with high execution times. The logs will typically show the query itself and its execution time.

Example log entry:
2023-10-27T10:30:00.123+0000 I  QUERY  [conn123] query db.collection plan summary: IXSCAN { field: 1 } ; explain: { ... } ; cursorid: 12345 ; nscanned: 1000000 ; nreturned: 10 ; keysexamined: 1000000 ; executionStats: { executionSuccess: true, nreturned: 10, executionTimeMillis: 5000, totalKeysExamined: 1000000, totalDocsExamined: 1000000 } ; duration: 5000ms

3

Use `explain()` on the identified slow queries to understand their execution plan and identify bottlenecks. Look for full table scans, inefficient joins, or missing indexes.

db.collection.find({ field: 'value' }).explain('executionStats')

4

Add appropriate indexes to support the slow queries. For example, if a query filters on `field`, create an index on it.

db.collection.createIndex({ field: 1 })

5

Rewrite the query to be more efficient, if possible. This might involve changing the query logic or reducing the amount of data being processed.

N/A (requires query analysis and rewriting)

2. Increase Operation Timeout Settings easy

Adjust MongoDB server-side timeouts to allow longer execution for legitimate, complex operations.

1

Connect to your MongoDB instance using the `mongosh` shell.

mongosh

2

Set the `maxTimeMS` option for the specific operation. This is a client-side setting but can be applied to individual operations. A value of 0 means no time limit.

db.collection.find({ field: 'value' }).maxTimeMS(60000) // 60 seconds

3

Alternatively, for server-side adjustments (use with caution), you can set the `operationTimeoutMillis` parameter. This affects all operations. A value of 0 means no timeout. This is typically done during mongod startup or by updating the configuration file.

In mongod.conf (e.g., /etc/mongod.conf):
operationTimeoutMillis: 120000

4

Restart the `mongod` process for configuration changes to take effect.

sudo systemctl restart mongod

3. Monitor System Resources medium

Ensure the MongoDB server has sufficient CPU, memory, and disk I/O to execute operations promptly.

1

Use system monitoring tools like `top`, `htop`, `vmstat`, or cloud provider monitoring dashboards to observe CPU and memory utilization on the MongoDB server.

top

2

Monitor disk I/O performance using tools like `iostat`. High disk latency can significantly slow down database operations.

iostat -xz 5

3

Check MongoDB's internal metrics for performance. You can use `db.serverStatus()` or connect to MongoDB with a monitoring tool.

db.serverStatus()

4

If resources are consistently strained, consider upgrading your hardware, increasing RAM, or optimizing disk configurations (e.g., using SSDs).

N/A (hardware/configuration change)

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Related Errors

5 related errors

MongoDB Error 262: Operation Time Limit Exceeded