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articles/cosmos-db/mongodb/vcore/limits.md

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+---
+title: Service Limits in Azure Cosmos DB for MongoDB vCore
+description: This document outlines the service limits for vCore-based Azure Cosmos DB for MongoDB.
+author: gahl-levy
+ms.author: gahllevy
+ms.service: cosmos-db
+ms.subservice: mongodb-vcore
+ms.topic: conceptual
+ms.date: 06/27/2024
+---
+
+# Service Limits in Azure Cosmos DB for MongoDB vCore
+
+This document provides an overview of the service limits for Azure Cosmos DB for MongoDB vCore.
+
+## Query and Execution Limits
+
+### Maximum MongoDB Query Memory Size
+- The maximum memory size for MongoDB queries depends on the tier. For example, for M80, the query memory size limit is approximately 150 MiB.
+- In sharded clusters, if a query pulls data across nodes, the limit on that data size is 1GB.
+
+### Maximum Execution Time for MongoDB Operations
+- Maximum transaction lifetime: 30 seconds.
+- Cursor lifetime: 10 minutes. Note: A cursorNotFound error might occur if the cursor exceeds its lifetime.
+- Default: 120 seconds. This can be overridden on a per-query basis using `maxTimeMS`.
+#### Example:
+```javascript
+db.collection.find({ field: "value" }).maxTimeMS(5000)
+```
+
+## Indexing Limits
+
+### General Indexing Limits
+- Maximum number of compound index paths: 32.
+- Maximum size for `_id` field value: 2KB.
+- Maximum size for index path: 256B.
+- Sorting is done in memory and does not push down to the index.
+- Background index builds are in private preview. To enable, customers need to file a support ticket.
+- A single index build can be in progress on the same collection.
+- The number of simultaneous index builds on different collections is configurable (default: 2).
+- Use the `currentOp` command to view the progress of long-running index builds.
+- Unique index builds are done in the foreground and block writes in the collection.
+- Composite indexes do not support geospatial indexes (2d, 2d sphere indexes).
+
+### Wildcard Indexing Limits
+- No specific limits; restrictions mirror MongoDB wildcard index restrictions.
+- For wildcard indexes, if the indexed field is an array of arrays, the entire embedded array is taken as a value instead of traversing its contents.
+
+### Geospatial Indexing Limits
+- No support for BigPolygons.
+- Composite indexes do not support geospatial indexes.
+- `$geoWithin` query does not support polygons with holes.
+- The `key` field is required in the `$geoNear` aggregation stage.
+- Indexes are recommended but not required for `$near`, `$nearSphere` query operators, and the `$geoNear` aggregation stage.
+
+### Text Index Limits
+- Only one text index can be defined on a collection.
+- Supports simple text searches only; advanced search capabilities like regular expression searches are not supported.
+- `hint()` is not supported in combination with a query using `$text` expression.
+- Sort operations cannot use the ordering of the text index.
+- Tokenization for Chinese, Japanese, Korean is not supported yet.
+- Case insensitive tokenization is not supported yet.
+
+### Vector Search Limits
+- Supported distance metrics: L2 (Euclidean), inner product, and cosine.
+- Supported indexing methods: IVFFLAT (GA) and HSNW.
+- Indexing vectors up to 2,000 dimensions in size.
+- Indexing applies to only one vector per path.
+- Only one index can be created per vector path.
+
+## Storage and Connection Limits
+
+### Disk IOPS
+| Disk Size (GiB) | IOPS per Disk |
+|-----------------|---------------|
+| 32              | 120           |
+| 64              | 240           |
+| 128             | 500           |
+| 256             | 1,100         |
+| 512             | 2,300         |
+| 1 TB            | 5,000         |
+| 2 TB            | 7,500         |
+| 4 TB            | 7,500         |
+| 8 TB            | 16,000        |
+| 16 TB           | 18,000        |
+| 32 TB           | 20,000        |
+
+## Cluster and Shard Limits
+
+### Cluster Tier
+- Maximum: M200. Contact support for higher tiers.
+
+### Shards
+- Maximum: 6 (in preview). Contact support for additional shards.
+
+### Secondary Regions
+- Maximum: 1. Contact support for additional regions.
+
+### Free Tier Limits
+The following limitations can be overidden by upgrading a paid tier
+- Maximum storage: 32GB.
+- Backup / Restore not supported (available in M25+)
+- High availability (HA) not supported (available in M30+)
+- HNSW vector indexes not supported (available in M40+)
+- Diagnostic logging not supported (available in M30+)
+- No service-level-agreement provided (requires HA to be enabled)
+
+## Collection, Index, and Database Limits
+
+### Indexes
+- Default maximum: 64.
+- Configurable up to: 300 indexes per collection.
+
+## Replication and HA Limits
+
+### Cross-Region Replication
+- Supported only on single shard (node) vCore clusters.
+- The following configurations are the same on both primary and replica clusters and cannot be changed on the replica cluster:
+  - Compute configuration
+  - Storage and shard count
+  - User accounts
+- HA is not supported on replica clusters.
+- Cross-region replication is not available on clusters with burstable compute.
+
+## Miscellaneous Limits
+
+### Nesting Levels
+- Maximum level of nesting for embedded objects/arrays on index definitions: 6.
+
+### Portal Mongo Shell Usage
+- The Portal Mongo Shell can be used for 120 minutes within a 24-hour window.
+
+## Next steps
+
+- Get started by [creating a cluster.](quickstart-portal.md).
+- Review options for [migrating from MongoDB to Azure Cosmos DB for MongoDB vCore.](migration-options.md)
+
+
+