Snippet Name: TempDB_Contention_Query
Tags:
Created Date: 2025-06-16 13:12:46
Last Modified Date: 2025-05-31 10:32:01
Dependencies:
DBA Notes:
Sample Output:
Title: TempDB Contention Query
Author: user
in sql server, can you give me a query that looks for contention in tempdb?
Author: ChatGPT
Contention in `tempdb` in SQL Server often occurs due to page latch contention, particularly on system tables like `sysobjects` or allocation structures (PFS, GAM, SGAM). To identify this contention, you can use the following query to monitor waits and contention:
### Query to Check TempDB Contention:
```sql
SELECT
session_id,
wait_type,
resource_description,
wait_time_ms,
blocking_session_id,
database_id,
command,
wait_resource
FROM sys.dm_os_waiting_tasks
WHERE wait_type LIKE 'PAGELATCH%'
AND resource_description LIKE '2:%'
ORDER BY wait_time_ms DESC;
```
### Explanation:
- **`wait_type LIKE 'PAGELATCH%'`**: Filters for latch waits that indicate contention on pages (e.g., `PAGELATCH_EX` or `PAGELATCH_SH`).
- **`resource_description LIKE '2:%'`**: Filters for tempdb (database ID `2` is always `tempdb`).
- **Columns of interest**:
- `session_id`: The session experiencing the wait.
- `wait_type`: Type of latch wait (exclusive, shared, etc.).
- `resource_description`: The specific page and file experiencing contention.
- `blocking_session_id`: The session causing the block, if applicable.
- `wait_time_ms`: Duration of the wait.
### Additional Steps:
If you identify contention, consider the following actions to mitigate it:
1. **Enable Trace Flag 1118**:
- Ensures uniform allocation for `tempdb` to reduce contention.
```sql
DBCC TRACEON(1118, -1);
```
Note: From SQL Server 2016 onward, this behavior is default.
2. **Increase the Number of TempDB Files**:
- Add multiple files of the same size for `tempdb` (equal to the number of logical processors, up to 8, then increment as needed).
3. **Monitor and Optimize Queries**:
- Check queries causing heavy `tempdb` usage with `sys.dm_exec_requests` and `sys.dm_exec_query_plan`.
By continuously monitoring the output of the query above, you can pinpoint the root cause of contention in your environment.
--------------------------------
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Author: user
what is the impact of cost threshold for parallelism and maxdop when it comes to multiple active result sets? i was told that MARS prefers sinlge threaded operations, is that correct?
Author: ChatGPT
When dealing with **Multiple Active Result Sets (MARS)** in SQL Server, understanding how **Cost Threshold for Parallelism** and **Max Degree of Parallelism (MAXDOP)** settings influence performance is critical. Here's how these factors interplay:
---
### **Key Considerations with MARS**
1. **Single-Threaded Preference of MARS**:
- MARS connections prefer **single-threaded operations**. This is because MARS uses a shared session context for multiple result sets and operations, requiring sequential execution to ensure predictable results. Parallel execution can introduce complexities in managing shared state and increase the chance of contention or unexpected behavior.
2. **Impact of MARS on Parallelism**:
- When MARS is enabled, SQL Server often avoids parallel plans for queries running under MARS sessions to maintain efficiency and predictability. This is a deliberate design choice to reduce contention and execution overhead.
---
### **Impact of Cost Threshold for Parallelism**
- The **Cost Threshold for Parallelism** (default is 5, which is very low) determines the threshold cost above which queries are eligible for parallel execution.
- Under MARS:
- A low **cost threshold** may still generate parallel plans in non-MARS contexts, but with MARS enabled, SQL Server actively biases towards single-threaded plans regardless of the cost.
- If the threshold is high (e.g., 50 or more), queries are unlikely to hit the cost limit in either scenario, favoring single-threaded execution.
- Recommendation:
- Use a sensible threshold (e.g., 25-50) that balances workloads outside MARS to minimize unnecessary parallelism.
---
### **Impact of MAXDOP**
- **MAXDOP** (Max Degree of Parallelism) controls the maximum number of cores a query can use during parallel execution.
- Under MARS:
- SQL Server discourages parallel plans, so **MAXDOP** is typically less impactful. Even if MAXDOP is set to a high value, MARS workloads will default to single-threaded operations when possible.
- High MAXDOP values can negatively affect non-MARS queries, leading to increased contention and resource usage.
---
### **Best Practices for MARS with Cost Threshold and MAXDOP**
1. **Adjust MAXDOP**:
- Keep MAXDOP low (e.g., 1 or 2) for environments where MARS is heavily used, as MARS workloads inherently lean toward single-threaded operations.
- For mixed workloads (MARS + non-MARS), use MAXDOP settings tailored to overall workload behavior.
2. **Set an Appropriate Cost Threshold for Parallelism**:
- Use a moderate value (e.g., 25-50) to ensure non-MARS workloads are efficiently parallelized while allowing MARS to operate with its single-threaded bias.
3. **Avoid Overloading MARS**:
- Avoid excessive concurrency or complex queries in MARS sessions, as this can degrade performance due to its single-threaded nature.
4. **Consider Alternatives to MARS**:
- In performance-critical scenarios, avoid MARS altogether and use separate connections to handle multiple result sets.
---
### **Why Does MARS Prefer Single-Threaded Operations?**
The MARS design ensures simplicity in managing multiple active queries within the same connection by avoiding parallelism-induced overhead. Parallel queries require managing inter-thread communication, synchronization, and state-sharing, which can conflict with MARS???s goal of reducing complexity and contention in a single connection.
---
### Conclusion
MARS does indeed prefer single-threaded execution, rendering settings like **Cost Threshold for Parallelism** and **MAXDOP** less impactful in MARS-heavy environments. However, these settings still affect other queries in the database, so tuning them appropriately remains essential for balanced performance.
--------------------------------
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Author: user
so does a sesison that is using MARS ignore maxdop and COST threshold,a nd forces a sinlge threaded operaiton in SQL2019 and above?
Author: ChatGPT
In SQL Server 2019 and above, a session using **Multiple Active Result Sets (MARS)** generally **does not ignore** the `MAXDOP` or `Cost Threshold for Parallelism` settings outright, but it **strongly biases toward single-threaded execution** for queries. Here???s why:
---
### 1. **MARS and Single-Threaded Execution**
- MARS sessions operate in a way that ensures sequential, predictable execution of queries within the same connection. This design discourages parallelism because:
- MARS relies on shared session state, which can be complicated by parallel query execution.
- Introducing parallelism in a MARS session increases the likelihood of contention and inter-thread dependencies, which MARS tries to avoid.
Thus, SQL Server often **forces single-threaded execution** for queries in MARS sessions, even if the query???s cost exceeds the `Cost Threshold for Parallelism` and regardless of the `MAXDOP` setting.
---
### 2. **Does MARS Ignore MAXDOP and Cost Threshold?**
- **`MAXDOP`**:
- While MARS does not explicitly "ignore" the `MAXDOP` setting, it effectively **overrides it** by defaulting to single-threaded plans in most scenarios.
- If a query in a MARS session can safely use parallelism (a rare case), it may respect `MAXDOP`. However, this is uncommon due to the inherent limitations of MARS.
- **`Cost Threshold for Parallelism`**:
- Similar to `MAXDOP`, the cost threshold is not entirely ignored, but MARS???s preference for single-threaded execution typically results in parallelism being bypassed, regardless of the query???s estimated cost.
---
### 3. **Behavior in SQL Server 2019 and Above**
SQL Server 2019 introduced enhancements to query processing, including **Intelligent Query Processing (IQP)** and features like **Batch Mode on Rowstore**. However, these changes do not alter the inherent single-threaded bias of MARS. Key points:
- MARS still forces single-threaded execution in most scenarios, prioritizing stability and predictability.
- Enhancements like **Adaptive Joins** and **Interleaved Execution** apply primarily to non-MARS workloads and are rarely leveraged in MARS contexts.
- Even with advanced query features, MARS sessions tend to override parallel execution plans.
---
### 4. **Verification of Single-Threaded Execution**
You can verify the actual execution behavior of a query in a MARS session by inspecting the query execution plan. Look for:
- **Non-parallel plan**: The plan will lack parallel operators (e.g., Parallelism: Distribute Streams or Gather Streams).
- **Query performance**: The execution will be constrained to a single thread, even if `MAXDOP` and `Cost Threshold for Parallelism` suggest otherwise.
---
### 5. **Best Practices for MARS**
Given the single-threaded nature of MARS, consider these best practices:
1. **Avoid heavy workloads in MARS sessions**:
- Offload computationally intensive queries to separate connections without MARS to allow parallelism.
2. **Use MAXDOP and Cost Threshold for Parallelism strategically**:
- Configure these settings based on your overall workload and not specifically for MARS, since they are less impactful for MARS queries.
3. **Monitor and analyze execution plans**:
- Use `sys.dm_exec_requests` and actual execution plans to confirm query behavior in MARS sessions.
---
### Summary
In SQL Server 2019 and above, MARS sessions effectively force single-threaded execution, **bypassing the practical impact** of `MAXDOP` and `Cost Threshold for Parallelism` in most cases. While these settings are not technically ignored, they are rendered moot due to MARS???s architectural constraints and bias toward single-threaded operations.
--------------------------------
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Author: user
how can i identify any sql server objects like procedures that are marked as encrypted?
Author: ChatGPT
To identify SQL Server objects such as stored procedures, functions, triggers, or views that are marked as **encrypted**, you can query the system catalog views in SQL Server. Specifically, the `is_encrypted` column in certain catalog views indicates whether the object is encrypted.
Here???s how you can identify encrypted objects:
---
### **Query to Identify Encrypted Objects**
```sql
SELECT
OBJECT_SCHEMA_NAME(o.object_id) AS SchemaName,
OBJECT_NAME(o.object_id) AS ObjectName,
o.type_desc AS ObjectType,
o.is_encrypted
FROM sys.objects o
WHERE o.is_encrypted = 1
ORDER BY SchemaName, ObjectName;
```
### **Explanation**
- **`OBJECT_SCHEMA_NAME(o.object_id)`**: Returns the schema of the object.
- **`OBJECT_NAME(o.object_id)`**: Returns the name of the object.
- **`o.type_desc`**: Provides the type of the object (e.g., `SQL_SCALAR_FUNCTION`, `SQL_STORED_PROCEDURE`).
- **`o.is_encrypted`**: Indicates if the object is encrypted (`1` for encrypted, `0` otherwise).
- **`sys.objects`**: This catalog view contains a row for each user-defined, schema-scoped object in the database.
---
### **Alternative Query for Encrypted Stored Procedures Only**
If you're specifically looking for **encrypted stored procedures**, you can refine the query as follows:
```sql
SELECT
OBJECT_SCHEMA_NAME(o.object_id) AS SchemaName,
OBJECT_NAME(o.object_id) AS ProcedureName,
o.type_desc AS ObjectType
FROM sys.objects o
WHERE o.type = 'P' -- 'P' denotes SQL Stored Procedures
AND o.is_encrypted = 1
ORDER BY SchemaName, ProcedureName;
```
---
### **Object Types of Interest**
The `type` column in `sys.objects` identifies object types. Common values include:
- `P`: Stored Procedure
- `FN`: Scalar Function
- `TF`: Table-Valued Function
- `IF`: Inline Table-Valued Function
- `V`: View
- `TR`: Trigger
To target specific types, adjust the `WHERE` clause accordingly.
---
### **Decrypting Encrypted Objects**
Encrypted objects cannot be directly viewed or decrypted through SQL Server's system views. If decryption is required, you would need:
1. The original source code (recommended to maintain backups).
2. Third-party tools for decrypting encrypted objects, if permitted by organizational policies.
**Note**: Encrypted objects are typically used to protect intellectual property. Ensure you have appropriate authorization before attempting to decrypt any object.
---
### Best Practices
- Regularly maintain backups of source code for procedures, functions, and other objects to avoid relying on SQL Server encryption as a form of source control.
- Use encryption judiciously, as it complicates management and debugging.
---
Run the above queries to identify encrypted objects in your SQL Server database.
--------------------------------
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Author: user
i cannot find a column is_encrypted in sys.objects
Author: ChatGPT
You are correct???there is no `is_encrypted` column in the `sys.objects` catalog view. The `is_encrypted` column exists in other catalog views, such as `sys.sql_modules`. Here's how you can correctly identify encrypted SQL Server objects:
---
### **Correct Query to Identify Encrypted Objects**
```sql
SELECT
OBJECT_SCHEMA_NAME(m.object_id) AS SchemaName,
OBJECT_NAME(m.object_id) AS ObjectName,
o.type_desc AS ObjectType,
m.is_encrypted
FROM sys.sql_modules m
INNER JOIN sys.objects o
ON m.object_id = o.object_id
WHERE m.is_encrypted = 1
ORDER BY SchemaName, ObjectName;
```
---
### **Explanation**
- **`sys.sql_modules`**:
- Contains metadata about the SQL text of stored procedures, functions, triggers, and views.
- The `is_encrypted` column here indicates whether the object is encrypted (`1` for encrypted, `0` otherwise).
- **`sys.objects`**:
- Provides general information about schema-scoped objects.
- We join `sys.objects` with `sys.sql_modules` to retrieve additional details like the object type (`type_desc`).
- **`OBJECT_SCHEMA_NAME()` and `OBJECT_NAME()`**:
- Functions to retrieve schema and object names for better readability.
- **Filter**:
- `WHERE m.is_encrypted = 1` ensures we only include encrypted objects.
---
### **Output Columns**
- **SchemaName**: The schema to which the object belongs.
- **ObjectName**: The name of the encrypted object.
- **ObjectType**: The type of the object (e.g., `SQL_STORED_PROCEDURE`, `SQL_SCALAR_FUNCTION`).
- **is_encrypted**: Indicates whether the object is encrypted.
---
### **Example Results**
| SchemaName | ObjectName | ObjectType | is_encrypted |
|------------|--------------|-----------------------|--------------|
| dbo | MyProcedure | SQL_STORED_PROCEDURE | 1 |
| dbo | MyFunction | SQL_SCALAR_FUNCTION | 1 |
---
### **Notes**
- Only schema-bound objects with associated SQL text are listed in `sys.sql_modules`. For other types of objects (e.g., tables or indexes), encryption does not apply.
- Encrypted objects cannot be viewed or altered directly. Always maintain a secure source code repository.
---
This query will correctly identify encrypted objects in your database.
--------------------------------
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Author: user
sys.sql_modules also does not have an is_ecrypted column
Author: ChatGPT
You're right again! My apologies for the confusion. The correct approach is to check the `is_encrypted` column in catalog views specific to objects like stored procedures, functions, and views. Here is the corrected method to identify encrypted objects in SQL Server:
---
### **Query to Identify Encrypted Objects**
```sql
SELECT
SCHEMA_NAME(schema_id) AS SchemaName,
name AS ObjectName,
type_desc AS ObjectType
FROM sys.objects
WHERE OBJECTPROPERTY(object_id, 'IsEncrypted') = 1
ORDER BY SchemaName, ObjectName;
```
---
### **Explanation**
- **`sys.objects`**:
- This catalog view contains a row for each user-defined, schema-scoped object.
- **`OBJECTPROPERTY(object_id, 'IsEncrypted')`**:
- The `OBJECTPROPERTY` function with the `'IsEncrypted'` property checks if an object (e.g., a procedure, function, or view) is encrypted.
- Returns `1` if the object is encrypted, `0` otherwise.
- **`SCHEMA_NAME(schema_id)`**:
- Converts the `schema_id` into the name of the schema for better readability.
- **Filters**:
- `WHERE OBJECTPROPERTY(object_id, 'IsEncrypted') = 1` ensures only encrypted objects are included.
---
### **Alternative for Specific Object Types**
To identify encrypted stored procedures specifically:
```sql
SELECT
SCHEMA_NAME(schema_id) AS SchemaName,
name AS ProcedureName,
type_desc AS ObjectType
FROM sys.objects
WHERE type = 'P' -- 'P' stands for stored procedures
AND OBJECTPROPERTY(object_id, 'IsEncrypted') = 1
ORDER BY SchemaName, ProcedureName;
```
For views, functions, or other objects, modify the `type` filter as follows:
- `V`: Views
- `FN`: Scalar Functions
- `TF`: Table-Valued Functions
- `IF`: Inline Table-Valued Functions
- `TR`: Triggers
---
### **Example Results**
| SchemaName | ObjectName | ObjectType |
|------------|--------------|-----------------------|
| dbo | MyProcedure | SQL_STORED_PROCEDURE |
| dbo | MyFunction | SQL_SCALAR_FUNCTION |
---
### Notes
- **Encrypted Objects**:
- Encrypted objects cannot be viewed or decrypted through SQL Server directly.
- Always maintain a backup of the original source code.
This query will correctly identify encrypted objects in your database without relying on non-existent columns.
--------------------------------
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Author: user
how can i find any objects that have been signed by a certificate?
Author: ChatGPT
To identify SQL Server objects that have been **signed by a certificate**, you can query the system catalog views related to certificates, database principals, and object permissions. Here???s how you can locate objects signed by certificates:
---
### **Query to Identify Signed Objects**
```sql
SELECT
SCHEMA_NAME(o.schema_id) AS SchemaName,
o.name AS ObjectName,
o.type_desc AS ObjectType,
dp.name AS CertificateName
FROM sys.crypt_properties cp
INNER JOIN sys.objects o
ON cp.major_id = o.object_id
INNER JOIN sys.certificates c
ON cp.thumbprint = c.thumbprint
INNER JOIN sys.database_principals dp
ON c.principal_id = dp.principal_id
ORDER BY SchemaName, ObjectName;
```
---
### **Explanation**
1. **`sys.crypt_properties`**:
- Tracks cryptographic properties for objects, such as signatures.
- Links signed objects to certificates or asymmetric keys via the `thumbprint` column.
2. **`sys.objects`**:
- Represents schema-scoped objects such as stored procedures, functions, or views.
- Joined to `sys.crypt_properties` on `object_id` to identify the signed object.
3. **`sys.certificates`**:
- Contains metadata about certificates in the database.
- The `thumbprint` column links certificates to cryptographic properties.
4. **`sys.database_principals`**:
- Represents principals in the database, including certificates.
- Helps map the certificate to a human-readable name.
5. **Columns**:
- **SchemaName**: Schema of the signed object.
- **ObjectName**: Name of the signed object.
- **ObjectType**: Type of the signed object (e.g., stored procedure, function).
- **CertificateName**: Name of the certificate used for signing.
---
### **Output Example**
| SchemaName | ObjectName | ObjectType | CertificateName |
|------------|--------------|-----------------------|-----------------|
| dbo | MyProcedure | SQL_STORED_PROCEDURE | MyCertificate |
| dbo | MyFunction | SQL_SCALAR_FUNCTION | CertFunctionSig |
---
### **Notes**
1. **Types of Signed Objects**:
- Stored procedures, functions, triggers, and other schema-scoped objects can be signed by certificates.
2. **Signatures**:
- Objects signed by certificates are often part of securing modules or granting permissions via signatures.
3. **Re-signing**:
- If the certificate or object changes, signatures may need to be re-applied.
This query will help you locate all objects in your database that have been signed by certificates.
--------------------------------
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Author: user
How can i find any objects realted to PolyBase?
Author: ChatGPT
To identify objects related to **PolyBase** in SQL Server, you can query system catalog views and metadata tables. PolyBase-related objects typically include **external tables**, **external data sources**, **external file formats**, and **credential objects**. Here's how you can find these objects:
---
### **1. External Tables**
PolyBase uses **external tables** to query data from external data sources.
```sql
SELECT
SCHEMA_NAME(schema_id) AS SchemaName,
name AS TableName,
type_desc AS ObjectType
FROM sys.objects
WHERE type = 'ET' -- 'ET' stands for External Table
ORDER BY SchemaName, TableName;
```
---
### **2. External Data Sources**
External data sources define the connection information for PolyBase queries.
```sql
SELECT
name AS DataSourceName,
type_desc AS DataSourceType,
location AS DataSourceLocation
FROM sys.external_data_sources
ORDER BY DataSourceName;
```
- **Columns**:
- `DataSourceName`: The name of the external data source.
- `DataSourceType`: Type of the data source (e.g., HADOOP, RDBMS).
- `DataSourceLocation`: The location of the external data source (e.g., server name, URL).
---
### **3. External File Formats**
External file formats describe the structure of files used in PolyBase queries.
```sql
SELECT
name AS FileFormatName,
format_type AS FormatType,
format_options AS Options
FROM sys.external_file_formats
ORDER BY FileFormatName;
```
- **Columns**:
- `FileFormatName`: Name of the file format.
- `FormatType`: File format type (e.g., DELIMITEDTEXT, PARQUET).
- `Options`: Additional format options, such as delimiter or encoding.
---
### **4. Credentials for External Access**
Credentials are used to authenticate external data access.
```sql
SELECT
name AS CredentialName,
credential_identity AS Identity
FROM sys.database_scoped_credentials
ORDER BY CredentialName;
```
- **Columns**:
- `CredentialName`: Name of the database-scoped credential.
- `Identity`: Identity (e.g., username) used for authentication.
---
### **5. External Tables Metadata**
For detailed information about external tables, join metadata views:
```sql
SELECT
et.name AS TableName,
eds.name AS DataSourceName,
eff.name AS FileFormatName,
et.location AS TableLocation
FROM sys.external_tables et
LEFT JOIN sys.external_data_sources eds
ON et.data_source_id = eds.data_source_id
LEFT JOIN sys.external_file_formats eff
ON et.file_format_id = eff.file_format_id
ORDER BY TableName;
```
- **Columns**:
- `TableName`: Name of the external table.
- `DataSourceName`: Associated external data source.
- `FileFormatName`: File format used by the table.
- `TableLocation`: Location of the external table.
---
### **6. PolyBase Configuration**
To check if PolyBase is enabled, run the following query:
```sql
SELECT
SERVERPROPERTY('IsPolyBaseInstalled') AS IsPolyBaseInstalled;
```
- Returns `1` if PolyBase is installed, `0` otherwise.
---
### Summary of PolyBase-Related Objects:
- **External Tables**: `sys.external_tables`
- **External Data Sources**: `sys.external_data_sources`
- **External File Formats**: `sys.external_file_formats`
- **Credentials**: `sys.database_scoped_credentials`
By using these queries, you can locate all PolyBase-related objects in your SQL Server instance.
--------------------------------
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Author: user
Are the tables the same for PolyBase as External Tables found in SQL2022?
Author: ChatGPT
In SQL Server 2022, **External Tables** have expanded functionality that includes traditional **PolyBase** use cases as well as integration with **Azure Synapse Link**, **SQL Server linked servers**, and **data virtualization** capabilities. While PolyBase's external tables remain compatible, there are some distinctions in how external tables are used and managed in SQL Server 2022.
Here are the key points to understand:
---
### **1. PolyBase External Tables**
- **PolyBase** in SQL Server primarily supports querying external data sources, such as:
- Hadoop
- Azure Blob Storage or Data Lake
- Flat files (CSV, Parquet)
- Other relational databases (via ODBC or native connectors)
- PolyBase external tables rely on:
- **`sys.external_tables`**
- **`sys.external_data_sources`**
- **`sys.external_file_formats`**
- **`sys.database_scoped_credentials`**
These catalog views are the same in SQL Server 2022 for managing traditional PolyBase external tables.
---
### **2. External Tables in SQL Server 2022**
In SQL Server 2022, external tables support broader scenarios beyond PolyBase, such as:
- **Data Virtualization**:
- Querying external relational databases like Oracle, PostgreSQL, or MySQL directly without PolyBase using linked servers.
- **Azure Synapse Link**:
- Querying operational databases such as Azure Cosmos DB or other cloud-native sources.
SQL Server 2022 introduces enhancements like:
- Simplified setup for external data sources (e.g., `CREATE EXTERNAL DATA SOURCE` for linked servers).
- Support for **multiple types of external connectors** beyond PolyBase.
---
### **3. Are the Catalog Views the Same?**
Yes, SQL Server 2022 uses the **same catalog views** for managing external tables, regardless of whether they are PolyBase-based or related to data virtualization:
#### **Key Catalog Views**:
1. **`sys.external_tables`**:
- Tracks all external tables, including those for PolyBase and other external sources.
- PolyBase external tables still appear here.
2. **`sys.external_data_sources`**:
- Stores metadata for all external data sources.
- Data source types now include `HADOOP`, `RDBMS`, `BLOB_STORAGE`, and others.
3. **`sys.external_file_formats`**:
- Applicable only for file-based external tables, primarily used in PolyBase scenarios.
4. **`sys.database_scoped_credentials`**:
- Manages credentials for external data access.
#### **Expanded Functionality in SQL Server 2022**:
While the views are the same, the range of supported data sources and scenarios has expanded in SQL Server 2022, particularly for **data virtualization** and **cloud-based integrations**.
---
### **4. How to Distinguish Between PolyBase and Non-PolyBase External Tables**
You can distinguish PolyBase-based external tables from others by querying the `sys.external_data_sources` view and inspecting the `type_desc` column:
#### **Query to Differentiate External Data Sources**:
```sql
SELECT
eds.name AS DataSourceName,
eds.type_desc AS DataSourceType,
eds.location AS Location
FROM sys.external_data_sources eds
ORDER BY DataSourceName;
```
#### **`type_desc` Values**:
- `HADOOP`: PolyBase Hadoop or Azure Data Lake sources.
- `RDBMS`: Relational database sources (PolyBase or linked servers).
- `BLOB_STORAGE`: PolyBase for Azure Blob Storage or files.
- `OTHER`: Non-PolyBase external data sources, such as linked servers or Azure Synapse Link.
---
### **5. Summary of Changes in SQL Server 2022**
| **Feature** | **PolyBase (SQL 2019)** | **SQL Server 2022 (All External Tables)** |
|----------------------------|-----------------------------------|------------------------------------------|
| **External Tables** | For PolyBase sources only | Expanded to include non-PolyBase sources |
| **Data Sources** | Limited to PolyBase sources | Includes linked servers and Synapse Link |
| **Catalog Views** | Same as SQL 2022 | Same as SQL 2019 |
| **File Formats** | Required for PolyBase | Optional for non-file-based sources |
SQL Server 2022 external tables retain compatibility with PolyBase objects while introducing broader functionality for non-PolyBase use cases.
--------------------------------
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Author: user
i have the following query about SQLserver extended events. can you help me put the Targz.eventfile into a single column using hte FOR XML conatenation method? SELECT
CASE WHEN [dxs].[name] IS NULL THEN ' Disabled' ELSE '' END AS SessionStatus,
CASE WHEN [sess].name IN ('system_health','AlwaysOn_health','telemetry_xevents') THEN ' Built-In' ELSE 'Custom' END AS SessionType,
[sess].[name],
[targz].[target_name],
[sess].[event_retention_mode_desc],
[sess].[max_dispatch_latency],
[sess].[max_memory],
[sess].[max_event_size],
[sess].[memory_partition_mode],
[sess].[memory_partition_mode_desc],
[sess].[track_causality],
[sess].[startup_state]
FROM sys.server_event_sessions [sess]
LEFT JOIN sys.[dm_xe_sessions] AS [dxs] ON [dxs].[name] = [sess].[name]
LEFT JOIN [sys].[dm_xe_session_targets] AS targz
ON [dxs].[address] = [targz].[event_session_address]
WHERE [targz].[target_name] IN('event_file', 'ring_buffer') --ring_buffer or event_file
Author: ChatGPT
To combine the `targz.target_name` column values into a single column using the `FOR XML PATH` method, you can group the data by the other columns and concatenate the target names. Here???s the updated query:
```sql
SELECT
CASE
WHEN [dxs].[name] IS NULL THEN ' Disabled'
ELSE ''
END AS SessionStatus,
CASE
WHEN [sess].name IN ('system_health', 'AlwaysOn_health', 'telemetry_xevents') THEN ' Built-In'
ELSE 'Custom'
END AS SessionType,
[sess].[name] AS SessionName,
STUFF((
SELECT ', ' + [t].[target_name]
FROM [sys].[dm_xe_session_targets] AS [t]
WHERE [dxs].[address] = [t].[event_session_address]
AND [t].[target_name] IN ('event_file', 'ring_buffer')
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)'), 1, 2, '') AS Targets,
[sess].[event_retention_mode_desc],
[sess].[max_dispatch_latency],
[sess].[max_memory],
[sess].[max_event_size],
[sess].[memory_partition_mode],
[sess].[memory_partition_mode_desc],
[sess].[track_causality],
[sess].[startup_state]
FROM sys.server_event_sessions [sess]
LEFT JOIN sys.[dm_xe_sessions] AS [dxs]
ON [dxs].[name] = [sess].[name]
WHERE EXISTS (
SELECT 1
FROM [sys].[dm_xe_session_targets] AS [t]
WHERE [dxs].[address] = [t].[event_session_address]
AND [t].[target_name] IN ('event_file', 'ring_buffer')
)
ORDER BY [sess].[name];
```
---
### **Explanation**
1. **`STUFF()` with `FOR XML PATH`**:
- Combines the `target_name` values (`event_file`, `ring_buffer`) into a single column.
- The `FOR XML PATH('')` clause concatenates the values as a comma-separated list.
- `STUFF()` removes the leading comma and space.
2. **Subquery in `STUFF()`**:
- The subquery retrieves all `target_name` values for the specific session.
3. **`WHERE EXISTS` Clause**:
- Ensures that only sessions with at least one target in `('event_file', 'ring_buffer')` are included.
4. **Output Columns**:
- Includes the concatenated targets in a single column (`Targets`).
---
### **Sample Output**
| SessionStatus | SessionType | SessionName | Targets | event_retention_mode_desc | max_dispatch_latency | ... |
|---------------|-------------|------------------|----------------------|---------------------------|----------------------|-----|
| Disabled | Built-In | system_health | event_file, ring_buffer | NO_EVENT_LOSS | 30 ms | ... |
| | Custom | custom_session | event_file | NO_EVENT_LOSS | 20 ms | ... |
This query aggregates the `target_name` values for each session into a single column while retaining all other details. Let me know if you have additional requirements!
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Author: user
for sql server, i have databases that are encrypted with TDE. how can i get the anme of the certificate from sys.certificates joined to teh database in sys.databases
Author: ChatGPT
To retrieve the name of the certificate used for Transparent Data Encryption (TDE) in SQL Server, you need to join the `sys.certificates` view with the `sys.databases` view. The link between these two is the `encryption_state` and the database's encryption key information stored in `sys.dm_database_encryption_keys`.
Here???s the query:
```sql
SELECT
d.name AS DatabaseName,
c.name AS CertificateName,
c.subject AS CertificateSubject,
c.start_date AS CertificateStartDate,
c.expiry_date AS CertificateExpiryDate
FROM sys.databases d
INNER JOIN sys.dm_database_encryption_keys dek
ON d.database_id = dek.database_id
INNER JOIN sys.certificates c
ON dek.encryptor_thumbprint = c.thumbprint
WHERE d.is_encrypted = 1 -- Filter only encrypted databases
ORDER BY d.name;
```
---
### **Explanation**
1. **`sys.databases`**:
- Contains a row for each database on the instance.
- The `is_encrypted` column indicates if the database is encrypted (`1` for encrypted, `0` for not encrypted).
2. **`sys.dm_database_encryption_keys`**:
- Contains information about the encryption keys used by TDE.
- The `encryptor_thumbprint` column links to the `thumbprint` column in `sys.certificates`.
3. **`sys.certificates`**:
- Stores metadata about the certificates in the database, including the `thumbprint` and other properties like `name`, `subject`, and validity dates.
4. **Filter**:
- The query filters for databases where `is_encrypted = 1` to show only TDE-protected databases.
5. **Columns in Output**:
- `DatabaseName`: Name of the database.
- `CertificateName`: Name of the certificate protecting the database encryption key.
- `CertificateSubject`: The subject of the certificate (e.g., description or identifier).
- `CertificateStartDate` and `CertificateExpiryDate`: Validity period of the certificate.
---
### **Sample Output**
| DatabaseName | CertificateName | CertificateSubject | CertificateStartDate | CertificateExpiryDate |
|----------------|------------------|--------------------|----------------------|-----------------------|
| MyDatabase | TDECert | SQL TDE Encryption | 2023-01-01 | 2028-01-01 |
| SecureDB | EncryptionCert | Secure Certificate | 2022-05-15 | 2027-05-15 |
This query allows you to identify the specific certificate protecting each TDE-encrypted database and its associated metadata.
--------------------------------
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Author: user
is there a dmv where i can query teh current authenticaiton mode allowed?
Author: ChatGPT
In SQL Server, you can determine the **current authentication mode** (Windows Authentication only or Mixed Mode Authentication) by querying the **`sys.configurations`** Dynamic Management View (DMV). The relevant configuration option is `login mode`.
Here???s the query to check the current authentication mode:
```sql
SELECT
name AS ConfigurationName,
value AS AuthenticationMode,
CASE
WHEN value = 1 THEN 'Windows Authentication'
WHEN value = 2 THEN 'Mixed Mode Authentication'
ELSE 'Unknown'
END AS AuthenticationModeDescription
FROM sys.configurations
WHERE name = 'login mode';
```
---
### **Explanation**
1. **`sys.configurations`**:
- This DMV stores server-level configuration settings.
- The `login mode` option determines the authentication mode.
2. **Columns in Output**:
- `ConfigurationName`: The name of the configuration option (`login mode`).
- `AuthenticationMode`: The raw value (`1` for Windows Authentication, `2` for Mixed Mode Authentication).
- `AuthenticationModeDescription`: A human-readable description of the current authentication mode.
---
### **Authentication Mode Values**
- `1`: Windows Authentication only.
- `2`: Mixed Mode Authentication (supports both SQL Server and Windows Authentication).
---
### **Example Output**
| ConfigurationName | AuthenticationMode | AuthenticationModeDescription |
|-------------------|---------------------|------------------------------------|
| login mode | 2 | Mixed Mode Authentication |
---
### Notes
- Changing the authentication mode requires administrative access. To modify it:
- Use SQL Server Management Studio (SSMS).
- Or update the setting programmatically using `sp_configure` and restart the SQL Server instance for the change to take effect.
This query will help you quickly identify the current authentication mode of your SQL Server instance.
--------------------------------
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