access timeout

Author: andrejtonev

pages/help-center/errors/transactions.mdx

@@ -12,6 +12,7 @@ import {CommunityLinks} from '/components/social-card/CommunityLinks'
 While working with Memgraph, you can encounter various transaction errors. Here are some of them, along with the instructions on how to handle them:
 - [Conflicting transactions](#conflicting-transaction)
 - [Transaction timeout](#transaction-timeout)
+- [Storage access timeout](#storage-access-timeout)
 
 ## Conflicting transactions
 
@@ -114,3 +115,32 @@ Here are the [instructions](/configuration/configuration-settings#using-flags-an
 
 
 <CommunityLinks/>
+
+## Storage access timeout
+Storage access errors can occur while preparing a query. Here are the storage access error messages you might encounter:
+- [Shared access timeout](#shared-access-timeout)
+- [Unique access timeout](#shared-access-timeout)
+
+### Error messages
+
+1. **Cannot access storage, unique access query is running. Try again later.**
+2. **Cannot get unique access to the storage. Try stopping other queries that are running in parallel.**
+
+### Understanding storage access timeout
+
+Storage access timeouts occur during query preparation when the query execution engine cannot get the required type of access to the storage. There are two types of storage access:
+
+- **Shared access:** Multiple queries can have shared access at the same time, but shared access cannot be granted while a query with unique access is running.
+- **Unique access:** Only one query can have unique access at a time, and no other query can have any type of access during that period.
+
+These timeouts prevent worker starvation and database blocking that could occur if queries were to wait indefinitely for storage access.
+
+### Handling storage access timeout
+
+When you encounter a storage access timeout:
+
+1. Check for long-running queries that might be blocking storage access
+2. Consider breaking down complex queries that require unique access into smaller operations
+3. Retry the query after other queries have completed
+4. If possible, schedule queries requiring unique access during periods of lower database activity
+