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SQL Server- Limit to Concurrent table queries?
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Problem
In SQL Server, or RDBMS systems in general, is there a limit to the number of concurrent queries that can be made against a table? How is it that N number of users can access the same physical data at the same time?
Update
Actually, more generally, forgetting about limits, how is it that two users can read from a table at the same time. Can someone explain this from a technical perceptive? If data is stored in a physical space on a disk, how is it that two users / processes can query that same physical data at the same time?
Update
Actually, more generally, forgetting about limits, how is it that two users can read from a table at the same time. Can someone explain this from a technical perceptive? If data is stored in a physical space on a disk, how is it that two users / processes can query that same physical data at the same time?
Solution
How is it that N number of users can access the same physical data at the same time?
This is done using transactions (honors ACID properties) & concurrency models. SQL server supports Optimistic concurrency as well as Pessimistic concurrency (default concurrency model) which inturn uses different isolation levels (read committed is the default isolation level ) and locking mechanism to allow multiple users access the data at the same time.
Refer to : SQL Server Transaction Locking and Row Versioning Guide
This is done using transactions (honors ACID properties) & concurrency models. SQL server supports Optimistic concurrency as well as Pessimistic concurrency (default concurrency model) which inturn uses different isolation levels (read committed is the default isolation level ) and locking mechanism to allow multiple users access the data at the same time.
Refer to : SQL Server Transaction Locking and Row Versioning Guide
Context
StackExchange Database Administrators Q#142714, answer score: 4
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