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Fix Atlas Search Issues

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  • Alert Conditions
  • Common Triggers
  • Fix the Immediate Problem
  • Implement a Long-Term Solution
  • Monitor Your Progress

Atlas Search triggers Atlas Search alerts when the amount of CPU and memory used by Atlas Search processes reaches a specified threshold. If the search process (mongot) runs out of memory, indexing and queries fail. You can configure Atlas Search alert conditions in the project alert settings modal. You can also view Atlas Search metrics with cluster monitoring.

Warning

If you shard a collection that already has an Atlas Search index, you might experience a brief period of query downtime when the collection begins to appear on a shard. Also, if you add a shard for an already sharded collection that contains an Atlas Search index, your search queries against that collection will fail until the initial sync process completes on the added shards. To learn more, see initial sync process.

You can configure the following alert conditions in the project-level alert settings page to trigger alerts.

Atlas Search: Index Replication Lag occurs if the approximate number of milliseconds that Atlas Search is behind in replicating changes from the oplog of mongod is above or below the threshold.

Atlas Search: Index Size on Disk occurs if the total size of all Atlas Search indexes on disk in bytes is above or below the threshold.

Atlas Search: Max Number of Lucene Docs occurs if the upper bound number of Lucene docs used to store Atlas Search indexes for a given replica set or shard is above the threshold.

Atlas Search: Number of Error Queries occurs if the number of queries for which Atlas Search is unable to return a response is above or below the threshold.

Atlas Search: Number of Index Fields occurs if the total number of unique fields present in the Atlas Search index is above or below the threshold.

Atlas Search: Number of Successful Queries occurs if the number of queries for which Atlas Search successfully returned a response is above or below the threshold.

Atlas Search: Total Number of Queries occurs if the number of queries submitted to Atlas Search is above or below the threshold.

Atlas Search Opcounter: Delete occurs if the total number of documents or fields (specified in the index definition) removed per second is above or below the threshold.

Atlas Search Opcounter: Getmore occurs if the total number of getmore commands run on all Atlas Search queries per second is above or below the threshold.

Atlas Search Opcounter: Insert occurs if the total number of documents or fields (specified in the index definition) that Atlas Search indexes per second is above or below the threshold.

Atlas Search Opcounter: Update occurs if the total number of documents or fields (specified in the index definition) that Atlas Search updates per second is above or below the threshold.

Insufficient disk space to support rebuilding search indexes occurs if your database deployment runs out of enough free disk space to support your Atlas Search indexes.

Note

This alert might appear when Atlas automatically upgrades your search indexes to enable new features. Your database deployment must have sufficient disk space for both the previous and new version of the index. After the index upgrade completes, Atlas deletes the old version of the index, which frees up disk space.

Search Memory: Resident occurs if the total bytes of resident memory occupied by the Atlas Search process is above or below the threshold.

Search Memory: Shared occurs if the total bytes of shared memory occupied by the Atlas Search process is above or below the threshold.

Search Memory: Virtual occurs if the total bytes of virtual memory occupied by the Atlas Search process is above or below the threshold.

Search Process: CPU (Kernel) % occurs if the percentage of time the CPU spent servicing operating system calls for the Atlas Search process is above the threshold.

Search Process: CPU (User) % occurs if the percentage of time the CPU spent servicing the Atlas Search process is above the threshold.

Search Process: Disk space used occurs if the total bytes of disk space used by the Atlas Search process is above the threshold.

Search Process: Ran out of memory occurs if the search process (mongot) runs out of memory. If the search process runs out of memory, indexing and queries fail.

Note

The Search Process: Ran out of memory alert runs automatically by default. You can configure the alert setting to disable this notification.

Atlas Search alerts often occur when you try to build a large or complex search index. These indexes remain in the Initial Sync phase until you resolve the memory issue.

If the search process (mongot) runs out of memory or disk space, you can upgrade your cluster to fix the immediate problem. You can select a cluster tier with more memory, storage, and IOPS.

To prevent Atlas Search alerts in the future, carefully review the Improve Atlas Search Performance for Atlas Search. Work to optimize your indexes.

View the available Atlas Search charts to monitor Atlas Search metrics.

Monitor Atlas Search metrics to evaluate and optimize your Atlas Search indexes.

To learn more, see View Cluster Metrics

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