Npgsql

https://www.npgsql.org/doc/
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Npgsql is a .NET data provider for PostgreSQL, providing ADO.NET-compatible database access to...
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### StartReplication(NpgsqlLogSequenceNumber, CancellationToken, uint)

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PhysicalReplicationConnection.html

Instructs the server to start streaming the WAL for physical replication, starting at the given WAL location. Returns an async enumerable of XLogDataMessage instances.

```APIDOC
## StartReplication(NpgsqlLogSequenceNumber, CancellationToken, uint)

### Description
Instructs the server to start streaming the WAL for physical replication, starting at WAL location `walLocation`. The server can reply with an error, for example if the requested section of WAL has already been recycled.

### Method
StartReplication

### Signature
public IAsyncEnumerable<XLogDataMessage> StartReplication(NpgsqlLogSequenceNumber walLocation, CancellationToken cancellationToken, uint timeline = 0)

### Parameters
- `walLocation` (NpgsqlLogSequenceNumber) - Required - The WAL location to begin streaming at.
- `cancellationToken` (CancellationToken) - Required - The token to be used for stopping the replication.
- `timeline` (uint) - Optional - Streaming starts on timeline tli.

### Returns
IAsyncEnumerable<XLogDataMessage> - A Task<TResult> representing an IAsyncEnumerable<T> that can be used to stream WAL entries in form of XLogDataMessage instances.

### Remarks
If the client requests a timeline that's not the latest but is part of the history of the server, the server will stream all the WAL on that timeline starting from the requested start point up to the point where the server switched to another timeline.
```

--------------------------------

### Collect Npgsql metrics with dotnet-counters

Source: https://www.npgsql.org/doc/diagnostics/metrics.html

Run this command to attach dotnet-counters to a running process and start reporting Npgsql metrics. Replace <PID> with the process ID of your application. The tool must be installed first.

```bash
dotnet counters monitor --counters Npgsql -p <PID>
```

--------------------------------

### Start logical replication with Npgsql

Source: https://www.npgsql.org/doc/replication.html

Minimal .NET program using Npgsql to start logical replication with the pgoutput plugin. Loops until cancellation and prints message types. Must call SetReplicationStatus or assign LastAppliedLsn/LastFlushedLsn to allow WAL cleanup.

```csharp
await using var conn = new LogicalReplicationConnection("<connection_string>");
await conn.Open();

var slot = new PgOutputReplicationSlot("blog_slot");

// The following will loop until the cancellation token is triggered, and will print message types coming from PostgreSQL:
var cancellationTokenSource = new CancellationTokenSource();
await foreach (var message in conn.StartReplication(
    slot, new PgOutputReplicationOptions("blog_pub", 1), cancellationTokenSource.Token))
{
    Console.WriteLine($"Received message type: {message.GetType().Name}");

    // Always call SetReplicationStatus() or assign LastAppliedLsn and LastFlushedLsn individually
    // so that Npgsql can inform the server which WAL files can be removed/recycled.
    conn.SetReplicationStatus(message.WalEnd);
}
```

--------------------------------

### SelectCommand

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataAdapter.html

Gets or sets the select command.

```APIDOC
## SelectCommand

### Description
Gets or sets the select command.

### Syntax
```csharp
public NpgsqlCommand? SelectCommand { get; set; }
```

### Property Value
NpgsqlCommand - The select command.

```

--------------------------------

### GetGuid(int)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataReader.html

Gets the value of the specified column as a globally-unique identifier (GUID).

```APIDOC
## GetGuid(int)

### Description
Gets the value of the specified column as a globally-unique identifier (GUID).

### Method
GetGuid

### Parameters
#### Path Parameters
- **ordinal** (int) - Required - The zero-based column ordinal.

### Returns
Guid - The value of the specified column.
```

--------------------------------

### StartReplication

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutputConnectionExtensions.html

Extension method to start logical streaming replication using the pgoutput plugin.

```APIDOC
## StartReplication(LogicalReplicationConnection, PgOutputReplicationSlot, PgOutputReplicationOptions, CancellationToken, NpgsqlLogSequenceNumber?)

### Description
Instructs the server to start the Logical Streaming Replication Protocol (pgoutput logical decoding plugin), starting at WAL location `walLocation` or at the slot's consistent point if `walLocation` isn't specified. The server can reply with an error, for example if the requested section of the WAL has already been recycled.

### Method
StartReplication

### Signature
public static IAsyncEnumerable<PgOutputReplicationMessage> StartReplication(this LogicalReplicationConnection connection, PgOutputReplicationSlot slot, PgOutputReplicationOptions options, CancellationToken cancellationToken, NpgsqlLogSequenceNumber? walLocation = null)

### Parameters
- **connection** (LogicalReplicationConnection) - Required - The LogicalReplicationConnection to use for starting replication.
- **slot** (PgOutputReplicationSlot) - Required - The replication slot that will be updated as replication progresses so that the server knows which WAL segments are still needed by the standby.
- **options** (PgOutputReplicationOptions) - Required - The collection of options passed to the slot's logical decoding plugin.
- **cancellationToken** (CancellationToken) - Required - The token to monitor for stopping the replication.
- **walLocation** (NpgsqlLogSequenceNumber?) - Optional - The WAL location to begin streaming at.

### Returns
IAsyncEnumerable<PgOutputReplicationMessage> - A Task<TResult> representing an IAsyncEnumerable<T> that can be used to stream WAL entries in form of PgOutputReplicationMessage instances.
```

--------------------------------

### Example output from logical replication

Source: https://www.npgsql.org/doc/replication.html

Example output when inserting a row into the replicated table, showing the sequence of message types received.

```plaintext
Received message type: BeginMessage
Received message type: RelationMessage
Received message type: InsertMessage
Received message type: CommitMessage
```

--------------------------------

### Basic Npgsql data source and command example

Source: https://www.npgsql.org/doc/index.html

Basic Npgsql usage: create a data source from a connection string, insert a parameterized row, and read all rows with a reader. Uses NpgsqlDataSource.Create and ADO.NET-style commands.

```csharp
var connectionString = "Host=myserver;Username=mylogin;Password=mypass;Database=mydatabase";
await using var dataSource = NpgsqlDataSource.Create(connectionString);

// Insert some data
await using (var cmd = dataSource.CreateCommand("INSERT INTO data (some_field) VALUES ($1)"))
{
    cmd.Parameters.AddWithValue("Hello world");
    await cmd.ExecuteNonQueryAsync();
}

// Retrieve all rows
await using (var cmd = dataSource.CreateCommand("SELECT some_field FROM data"))
await using (var reader = await cmd.ExecuteReaderAsync())
{
    while (await reader.ReadAsync())
    {
        Console.WriteLine(reader.GetString(0));
    }
}
```

--------------------------------

### NpgsqlCube.ToSubset example

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlCube.html

Shows how to use ToSubset to extract a single dimension, drop dimensions, or reorder them. The comments show the resulting cube text format.

```csharp
var cube = new NpgsqlCube(new[] { 1, 3, 5 }, new[] { 6, 7, 8 }); // '(1,3,5),(6,7,8)'
cube.ToSubset(1); // '(3),(7)'
cube.ToSubset(2, 1, 0, 0); // '(5,3,1,1),(8,7,6,6)'
```

--------------------------------

### Disable infinity conversions with AppContext switch

Source: https://www.npgsql.org/doc/types/datetime.html

Place this at the start of your application to opt out of mapping PostgreSQL infinity values to .NET MinValue/MaxValue. This behavior is enabled by default starting with Npgsql 6.0.

```csharp
AppContext.SetSwitch("Npgsql.DisableDateTimeInfinityConversions", true);
```

--------------------------------

### NpgsqlTsVector.Count

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlTsVector.html

Gets the number of lexemes.

```APIDOC
## NpgsqlTsVector.Count

### Description
Gets the number of lexemes.

### Property Value
- **int** - The number of lexemes.
```

--------------------------------

### Set up OpenTelemetry tracing for Npgsql

Source: https://www.npgsql.org/doc/diagnostics/tracing.html

Configures a tracer provider with Npgsql tracing, console exporter, and optional application source. Requires the Npgsql.OpenTelemetry NuGet package. After setup, Npgsql trace data appears in the console.

```csharp
using var tracerProvider = Sdk.CreateTracerProviderBuilder()
    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("npgsql-tester"))
    .SetSampler(new AlwaysOnSampler())
    // This optional activates tracing for your application, if you trace your own activities:
    .AddSource("MyApp")
    // This activates up Npgsql's tracing:
    .AddNpgsql()
    // This prints tracing data to the console:
    .AddConsoleExporter()
    .Build();
```

--------------------------------

### StartReplication(PhysicalReplicationSlot?, NpgsqlLogSequenceNumber, CancellationToken, uint)

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PhysicalReplicationConnection.html

Starts physical replication streaming from a specified WAL location.

```APIDOC
## StartReplication(PhysicalReplicationSlot?, NpgsqlLogSequenceNumber, CancellationToken, uint)

### Description
Instructs the server to start streaming the WAL for physical replication, starting at WAL location `walLocation`. The server can reply with an error, for example if the requested section of the WAL has already been recycled.

### Method
StartReplication

### Signature
public IAsyncEnumerable<XLogDataMessage> StartReplication(PhysicalReplicationSlot? slot, NpgsqlLogSequenceNumber walLocation, CancellationToken cancellationToken, uint timeline = 0)

### Parameters
- **slot** (PhysicalReplicationSlot) - Required - The replication slot that will be updated as replication progresses so that the server knows which WAL segments are still needed by the standby.
- **walLocation** (NpgsqlLogSequenceNumber) - Required - The WAL location to begin streaming at.
- **cancellationToken** (CancellationToken) - Required - The token to be used for stopping the replication.
- **timeline** (uint) - Optional - Streaming starts on timeline tli.

### Returns
IAsyncEnumerable<XLogDataMessage> - A Task<TResult> representing an IAsyncEnumerable<T> that can be used to stream WAL entries in form of XLogDataMessage instances.

### Remarks
If the client requests a timeline that's not the latest but is part of the history of the server, the server will stream all the WAL on that timeline starting from the requested start point up to the point where the server switched to another timeline.
```

--------------------------------

### Width

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the width of the box.

```APIDOC
## Width

### Description
Gets the width of the box.

### Property
`public double Width { get; }`

### Property Value
- **double** - The width of the box.

```

--------------------------------

### Height

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the height of the box.

```APIDOC
## Height

### Description
Gets the height of the box.

### Property
`public double Height { get; }`

### Property Value
- **double** - The height of the box.

```

--------------------------------

### NpgsqlDataAdapter(string, string)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataAdapter.html

Constructor that initializes the adapter with a select command text and a connection string.

```APIDOC
## NpgsqlDataAdapter(string, string)

### Description
Constructor that initializes the adapter with a select command text and a connection string.

### Syntax
```csharp
public NpgsqlDataAdapter(string selectCommandText, string selectConnectionString)
```

### Parameters
- `selectCommandText` (string) - Required - The select command text.
- `selectConnectionString` (string) - Required - The connection string.

### Returns
A new instance of NpgsqlDataAdapter.

```

--------------------------------

### UserName

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Gets the user name.

```APIDOC
## UserName

### Description
Gets the user name.

### Property Value
string?

### Code Example
```csharp
public string? UserName { get; }
```
```

--------------------------------

### StartReplication

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.TestDecodingConnectionExtensions.html

Extension method to start streaming WAL data using the test_decoding logical decoding plugin.

```APIDOC
## StartReplication(LogicalReplicationConnection, TestDecodingReplicationSlot, CancellationToken, TestDecodingOptions?, NpgsqlLogSequenceNumber?)

### Description
Instructs the server to start streaming the WAL for logical replication using the test_decoding logical decoding plugin, starting at WAL location `walLocation` or at the slot's consistent point if `walLocation` isn't specified. The server can reply with an error, for example if the requested section of the WAL has already been recycled.

### Method
StartReplication

### Signature
public static IAsyncEnumerable<TestDecodingData> StartReplication(this LogicalReplicationConnection connection, TestDecodingReplicationSlot slot, CancellationToken cancellationToken, TestDecodingOptions? options = null, NpgsqlLogSequenceNumber? walLocation = null)

### Parameters
- **connection** (LogicalReplicationConnection) - Required - The LogicalReplicationConnection to use for starting replication.
- **slot** (TestDecodingReplicationSlot) - Required - The replication slot that will be updated as replication progresses so that the server knows which WAL segments are still needed by the standby.
- **cancellationToken** (CancellationToken) - Required - The token to monitor for stopping the replication.
- **options** (TestDecodingOptions) - Optional - The collection of options passed to the slot's logical decoding plugin.
- **walLocation** (NpgsqlLogSequenceNumber?) - Optional - The WAL location to begin streaming at.

### Returns
IAsyncEnumerable<TestDecodingData> - A Task<TResult> representing an IAsyncEnumerable<T> that can be used to stream WAL entries in form of TestDecodingData instances.
```

--------------------------------

### Prepare NpgsqlCommand with parameters

Source: https://www.npgsql.org/doc/prepare.html

Prepare a command without parameter values, then set values and execute repeatedly. Parameters must have DbType, NpgsqlDbType, or DataTypeName set before PrepareAsync() to identify their type. Alternatively, set parameter values before preparing to infer types as usual.

```csharp
var cmd = new NpgsqlCommand(...);
cmd.Parameters.Add("param", NpgsqlDbType.Integer);
await cmd.PrepareAsync();
// Set parameters
await cmd.ExecuteNonQueryAsync();
// And so on
```

--------------------------------

### TruncateMessage.Relations

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutput.Messages.TruncateMessage.html

Gets the relations being truncated.

```APIDOC
## TruncateMessage.Relations

### Description
Gets the relations being truncated.

### Property
`public IReadOnlyList<RelationMessage> Relations { get; }`

### Property Value
- **IReadOnlyList<RelationMessage>** - The relations being truncated.

```

--------------------------------

### NpgsqlBinaryImporter.StartRow()

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlBinaryImporter.html

Starts writing a new row in the binary import.

```APIDOC
## NpgsqlBinaryImporter.StartRow()

### Description
Starts writing a single row, must be invoked before writing any columns.

### Method
`public void StartRow()`

### Parameters
None.
```

--------------------------------

### PrepareMessageBase.PrepareLsn

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutput.Messages.PrepareMessageBase.html

Gets the LSN of the prepare.

```APIDOC
## PrepareMessageBase.PrepareLsn

### Description
Gets the LSN of the prepare.

### Property Value
- **NpgsqlLogSequenceNumber** - The LSN of the prepare.

### Remarks
This property is read-only and is set during message construction.
```

--------------------------------

### Text

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlTsVector.Lexeme.html

Gets or sets the text of the lexeme.

```APIDOC
## Text

### Description
Gets or sets the text of the lexeme.

### Property
`public string Text { readonly get; set; }`

### Returns
string - The text of the lexeme.

```

--------------------------------

### Build()

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataSourceBuilder.html

Builds and returns an NpgsqlDataSource which is ready for use.

```APIDOC
## Build()

### Description
Builds and returns an NpgsqlDataSource which is ready for use.

### Method
Build

### Returns
- NpgsqlDataSource - The built data source.
```

--------------------------------

### NpgsqlDataAdapter(NpgsqlCommand)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataAdapter.html

Constructor that initializes the adapter with a select command.

```APIDOC
## NpgsqlDataAdapter(NpgsqlCommand)

### Description
Constructor that initializes the adapter with a select command.

### Syntax
```csharp
public NpgsqlDataAdapter(NpgsqlCommand selectCommand)
```

### Parameters
- `selectCommand` (NpgsqlCommand) - Required - The select command to use.

### Returns
A new instance of NpgsqlDataAdapter.

```

--------------------------------

### Top

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the top coordinate of the box.

```APIDOC
## Top

### Description
Gets the top coordinate of the box.

### Property
`public double Top { get; }`

### Property Value
- **double** - The top coordinate.

```

--------------------------------

### Right

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the right coordinate of the box.

```APIDOC
## Right

### Description
Gets the right coordinate of the box.

### Property
`public double Right { get; }`

### Property Value
- **double** - The right coordinate.

```

--------------------------------

### BeginBinaryImport(string)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Begins a binary COPY FROM STDIN operation for high-performance data import to a PostgreSQL table.

```APIDOC
## BeginBinaryImport(string)

### Description
Begins a binary COPY FROM STDIN operation, a high-performance data import mechanism to a PostgreSQL table.

### Method
BeginBinaryImport

### Signature
public NpgsqlBinaryImporter BeginBinaryImport(string copyFromCommand)

### Parameters
- **copyFromCommand** (string) - Required - A COPY FROM STDIN SQL command

### Returns
NpgsqlBinaryImporter - A NpgsqlBinaryImporter which can be used to write rows and columns

### Remarks
See https://www.postgresql.org/docs/current/static/sql-copy.html.
```

--------------------------------

### NpgsqlCommand()

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Initializes a new instance of the NpgsqlCommand class.

```APIDOC
## NpgsqlCommand()

### Description
Initializes a new instance of the NpgsqlCommand class.

### Method
Constructor

### Signature
public NpgsqlCommand()

### Parameters
None.

```

--------------------------------

### Left

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the left coordinate of the box.

```APIDOC
## Left

### Description
Gets the left coordinate of the box.

### Property
`public double Left { get; }`

### Property Value
- **double** - The left coordinate.

```

--------------------------------

### Set up replication user in pg_hba.conf

Source: https://www.npgsql.org/doc/replication.html

Add to pg_hba.conf to allow the replication user to connect. The user must exist and be a superuser or have the replication attribute.

```plaintext
host     replication     repuser     0.0.0.0/0     md5
```

--------------------------------

### Bottom

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlBox.html

Gets the bottom coordinate of the box.

```APIDOC
## Bottom

### Description
Gets the bottom coordinate of the box.

### Property
`public double Bottom { get; }`

### Property Value
- **double** - The bottom coordinate.

```

--------------------------------

### Create npgsql_tests user and database in psql

Source: https://www.npgsql.org/doc/dev/tests.html

Run these psql commands as the postgres superuser to create the npgsql_tests account and database. Superuser access is required to create and drop test databases and load extensions like hstore and postgis.

```sql
$ psql -h localhost -U postgres
postgres=# CREATE USER npgsql_tests PASSWORD 'npgsql_tests' SUPERUSER;
postgres=# CREATE DATABASE npgsql_tests OWNER npgsql_tests;
```

--------------------------------

### Encoding

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.ReplicationConnection.html

Gets the client encoding for the connection.

```APIDOC
## [PROPERTY] Encoding

### Description
The client encoding for the connection. This can only be called when there is an active connection.

### Property Signature
```csharp
public Encoding Encoding { get; }
```

### Property Value
- **Type**: Encoding

```

--------------------------------

### BeginBinaryImportAsync(string, CancellationToken)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Asynchronously begins a binary COPY FROM STDIN operation for high-performance data import to a PostgreSQL table.

```APIDOC
## BeginBinaryImportAsync(string, CancellationToken)

### Description
Begins a binary COPY FROM STDIN operation, a high-performance data import mechanism to a PostgreSQL table.

### Method
BeginBinaryImportAsync

### Signature
public Task<NpgsqlBinaryImporter> BeginBinaryImportAsync(string copyFromCommand, CancellationToken cancellationToken = default)

### Parameters
- **copyFromCommand** (string) - Required - A COPY FROM STDIN SQL command
- **cancellationToken** (CancellationToken) - Optional - An optional token to cancel the asynchronous operation. The default value is None.

### Returns
Task<NpgsqlBinaryImporter> - A NpgsqlBinaryImporter which can be used to write rows and columns

### Remarks
See https://www.postgresql.org/docs/current/static/sql-copy.html.
```

--------------------------------

### State

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Gets the current state of the connection.

```APIDOC
## State

### Description
Gets whether the current state of the connection is Open or Closed.

### Property Value
ConnectionState

### Remarks
ConnectionState.Open, ConnectionState.Closed or ConnectionState.Connecting

### Code Example
```csharp
[Browsable(false)]
public override ConnectionState State { get; }
```
```

--------------------------------

### Write and read NodaTime Instant with Npgsql

Source: https://www.npgsql.org/doc/types/nodatime.html

Shows how to write a NodaTime Instant to a PostgreSQL timestamp with time zone column and read it back as an Instant. Requires the NodaTime plugin to be set up. The example uses NpgsqlCommand with parameters and ExecuteReaderAsync.

```csharp
// Write NodaTime Instant to PostgreSQL "timestamp with time zone" (UTC)
await using (var cmd = new NpgsqlCommand(@"INSERT INTO mytable (my_timestamptz) VALUES ($1)", conn))
{
    cmd.Parameters.Add(new() { Value = Instant.FromUtc(2011, 1, 1, 10, 30) });
    await cmd.ExecuteNonQueryAsync();
}

// Read timestamp back from the database as an Instant
await using (var cmd = new NpgsqlCommand(@"SELECT my_timestamptz FROM mytable", conn))
await using (var reader = await cmd.ExecuteReaderAsync())
{
    await reader.ReadAsync();
    var instant = reader.GetFieldValue<Instant>(0);
}
```

--------------------------------

### Values

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnectionStringBuilder.html

Property to get the collection of values.

```APIDOC
## Values

### Description
Gets an ICollection containing the values in the NpgsqlConnectionStringBuilder.

### Property Value
ICollection<object>

### Syntax
```csharp
public ICollection<object?> Values { get; }
```
```

--------------------------------

### Username

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnectionStringBuilder.html

Property to get or set the username.

```APIDOC
## Username

### Description
The username to connect with.

### Property Value
string

### Syntax
```csharp
public string? Username { get; set; }
```
```

--------------------------------

### Prepare()

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlBatch.html

Creates a prepared (or compiled) version of the batch on the data source.

```APIDOC
## Prepare()

### Description
Creates a prepared (or compiled) version of the batch, or of each of its commands, on the data source.

### Method
Prepare

### Signature
public override void Prepare()
```

--------------------------------

### Password

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnectionStringBuilder.html

Gets or sets the password to connect with.

```APIDOC
## Password

### Description
The password to connect with.

### Property Value
string

### Syntax
```csharp
public string? Password { get; set; }
```
```

--------------------------------

### NpgsqlDataAdapter(string, NpgsqlConnection)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataAdapter.html

Constructor that initializes the adapter with a select command text and a connection.

```APIDOC
## NpgsqlDataAdapter(string, NpgsqlConnection)

### Description
Constructor that initializes the adapter with a select command text and a connection.

### Syntax
```csharp
public NpgsqlDataAdapter(string selectCommandText, NpgsqlConnection selectConnection)
```

### Parameters
- `selectCommandText` (string) - Required - The select command text.
- `selectConnection` (NpgsqlConnection) - Required - The connection to use.

### Returns
A new instance of NpgsqlDataAdapter.

```

--------------------------------

### ReplicationValue.GetFieldName()

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutput.ReplicationValue.html

Gets the name of the specified column.

```APIDOC
## GetFieldName()

### Description
Gets the name of the specified column.

### Method
GetFieldName

### Signature
public string GetFieldName()

### Returns
string - The name of the specified column.
```

--------------------------------

### NpgsqlCommand(string?, NpgsqlConnection?, NpgsqlTransaction?)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Initializes a new instance of the NpgsqlCommand class with the text of the query, a NpgsqlConnection, and the NpgsqlTransaction.

```APIDOC
## NpgsqlCommand(string?, NpgsqlConnection?, NpgsqlTransaction?)

### Description
Initializes a new instance of the NpgsqlCommand class with the text of the query, a NpgsqlConnection, and the NpgsqlTransaction.

### Method
Constructor

### Signature
public NpgsqlCommand(string? cmdText, NpgsqlConnection? connection, NpgsqlTransaction? transaction)

### Parameters
- **cmdText** (string) - The text of the query.
- **connection** (NpgsqlConnection) - A NpgsqlConnection that represents the connection to a PostgreSQL server.
- **transaction** (NpgsqlTransaction) - The NpgsqlTransaction in which the NpgsqlCommand executes.

```

--------------------------------

### NpgsqlCommand(string?, NpgsqlConnection?)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Initializes a new instance of the NpgsqlCommand class with the text of the query and a NpgsqlConnection.

```APIDOC
## NpgsqlCommand(string?, NpgsqlConnection?)

### Description
Initializes a new instance of the NpgsqlCommand class with the text of the query and a NpgsqlConnection.

### Method
Constructor

### Signature
public NpgsqlCommand(string? cmdText, NpgsqlConnection? connection)

### Parameters
- **cmdText** (string) - The text of the query.
- **connection** (NpgsqlConnection) - A NpgsqlConnection that represents the connection to a PostgreSQL server.

```

--------------------------------

### PrepareMessageBase.TransactionPrepareTimestamp

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutput.Messages.PrepareMessageBase.html

Gets the prepare timestamp of the transaction.

```APIDOC
## PrepareMessageBase.TransactionPrepareTimestamp

### Description
Gets the prepare timestamp of the transaction.

### Property Value
- **DateTime** - The prepare timestamp of the transaction.

### Remarks
This property is read-only and is set during message construction.
```

--------------------------------

### StartReplication(PhysicalReplicationSlot, CancellationToken)

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PhysicalReplicationConnection.html

Starts physical replication streaming using the slot's restart LSN.

```APIDOC
## StartReplication(PhysicalReplicationSlot, CancellationToken)

### Description
Instructs the server to start streaming the WAL for physical replication, starting at the WAL location and timeline id specified in `slot`. The server can reply with an error, for example if the requested section of the WAL has already been recycled.

### Method
StartReplication

### Signature
public IAsyncEnumerable<XLogDataMessage> StartReplication(PhysicalReplicationSlot slot, CancellationToken cancellationToken)

### Parameters
- **slot** (PhysicalReplicationSlot) - Required - The replication slot that will be updated as replication progresses so that the server knows which WAL segments are still needed by the standby. The `slot` must contain a valid RestartLsn to be used for this overload.
- **cancellationToken** (CancellationToken) - Required - The token to be used for stopping the replication.

### Returns
IAsyncEnumerable<XLogDataMessage> - A Task<TResult> representing an IAsyncEnumerable<T> that can be used to stream WAL entries in form of XLogDataMessage instances.

### Remarks
If the client requests a timeline that's not the latest but is part of the history of the server, the server will stream all the WAL on that timeline starting from the requested start point up to the point where the server switched to another timeline.
```

--------------------------------

### this[string]

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlParameterCollection.html

Gets the NpgsqlParameter with the specified name.

```APIDOC
## [PROPERTY] this[string]

### Description
Gets the NpgsqlParameter with the specified name.

### Property Signature
`public NpgsqlParameter this[string parameterName] { get; set; }`

### Parameters
- **parameterName** (string) - The name of the NpgsqlParameter to retrieve.

### Property Value
- **NpgsqlParameter** - The NpgsqlParameter with the specified name, or a null reference if the parameter is not found.
```

--------------------------------

### this[int]

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlParameterCollection.html

Gets the NpgsqlParameter at the specified index.

```APIDOC
## [PROPERTY] this[int]

### Description
Gets the NpgsqlParameter at the specified index.

### Property Signature
`public NpgsqlParameter this[int index] { get; set; }`

### Parameters
- **index** (int) - The zero-based index of the NpgsqlParameter to retrieve.

### Property Value
- **NpgsqlParameter** - The NpgsqlParameter at the specified index.
```

--------------------------------

### ConfigureTypeLoading(Action<NpgsqlTypeLoadingOptionsBuilder>)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataSourceBuilder.html

Configures type loading options for the DataSource.

```APIDOC
## ConfigureTypeLoading(Action<NpgsqlTypeLoadingOptionsBuilder>)

### Description
Configures type loading options for the DataSource.

### Method
ConfigureTypeLoading

### Parameters
- `configureAction` (Action<NpgsqlTypeLoadingOptionsBuilder>) - Required - The action to configure type loading options.

### Returns
- NpgsqlDataSourceBuilder - The same builder instance so that multiple calls can be chained.
```

--------------------------------

### BeginRawBinaryCopyAsync(string, CancellationToken)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Begins a raw binary COPY operation (TO STDOUT or FROM STDIN) for high-performance data export/import.

```APIDOC
## BeginRawBinaryCopyAsync(string, CancellationToken)

### Description
Begins a raw binary COPY operation (TO STDOUT or FROM STDIN), a high-performance data export/import mechanism to a PostgreSQL table. Unlike other COPY API methods, it does not implement any encoding/decoding and is unsuitable for structured import/export operations. It is useful mainly for exporting a table as an opaque blob for later import.

### Method
BeginRawBinaryCopyAsync

### Signature
public Task<NpgsqlRawCopyStream> BeginRawBinaryCopyAsync(string copyCommand, CancellationToken cancellationToken = default)

### Parameters
- **copyCommand** (string) - Required - A COPY TO STDOUT or COPY FROM STDIN SQL command.
- **cancellationToken** (CancellationToken) - Optional - An optional token to cancel the asynchronous operation. The default value is None.

### Returns
Task<NpgsqlRawCopyStream> - A NpgsqlRawCopyStream that can be used to read or write raw binary data.

### Remarks
See https://www.postgresql.org/docs/current/static/sql-copy.html.
```

--------------------------------

### DeleteMessage.Relation

Source: https://www.npgsql.org/doc/api/Npgsql.Replication.PgOutput.Messages.DeleteMessage.html

Gets the relation for this delete message.

```APIDOC
## DeleteMessage.Relation

### Description
Gets the relation for this delete message.

### Property
`public RelationMessage Relation { get; }`

### Property Value
- **RelationMessage** - The relation for this delete message.
```

--------------------------------

### Where

Source: https://www.npgsql.org/doc/api/Npgsql.PostgresException.html

Gets an indication of the context in which the error occurred.

```APIDOC
## Where

### Description
Gets an indication of the context in which the error occurred.

### Property Value
string (nullable)
```

--------------------------------

### ConfigureBatchEnrichmentCallback(Action<Activity, NpgsqlBatch>?)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlTracingOptionsBuilder.html

Configures a callback to enrich the Activity emitted for an NpgsqlBatch.

```APIDOC
## ConfigureBatchEnrichmentCallback(Action<Activity, NpgsqlBatch>?)

### Description
Configures a callback that can enrich the Activity emitted for the given NpgsqlBatch.

### Method
ConfigureBatchEnrichmentCallback

### Signature
public NpgsqlTracingOptionsBuilder ConfigureBatchEnrichmentCallback(Action<Activity, NpgsqlBatch>? batchEnrichmentCallback)

### Parameters
- **batchEnrichmentCallback** (Action<Activity, NpgsqlBatch>) - Required - The callback to enrich the Activity.

### Returns
NpgsqlTracingOptionsBuilder
```

--------------------------------

### NpgsqlBatch(NpgsqlConnection?, NpgsqlTransaction?)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlBatch.html

Constructor for creating a new NpgsqlBatch instance.

```APIDOC
## NpgsqlBatch Constructor

### Description
Initializes a new NpgsqlBatch instance with an optional connection and transaction.

### Method
Constructor

### Signature
`public NpgsqlBatch(NpgsqlConnection? connection = null, NpgsqlTransaction? transaction = null)`

### Parameters
- **connection** (NpgsqlConnection?) - Optional - A NpgsqlConnection that represents the connection to a PostgreSQL server.
- **transaction** (NpgsqlTransaction?) - Optional - The NpgsqlTransaction in which the NpgsqlCommand executes.
```

--------------------------------

### SqlState

Source: https://www.npgsql.org/doc/api/Npgsql.PostgresException.html

Gets the SQLSTATE code for the error.

```APIDOC
## SqlState

### Description
Gets the SQLSTATE code for the error.

### Property Value
string

### Remarks
Always present. Constants are defined in PostgresErrorCodes. See https://www.postgresql.org/docs/current/static/errcodes-appendix.html
```

--------------------------------

### Configure NpgsqlDataSource with LoggerFactory for console logging

Source: https://www.npgsql.org/doc/diagnostics/logging.html

Creates a LoggerFactory with AddConsole, configures an NpgsqlDataSourceBuilder with it, and opens a connection to execute a command. Any connections from the data source will log via the provided logger factory.

```csharp
// Create a Microsoft.Extensions.Logging LoggerFactory, configuring it with the providers,
// log levels and other desired configuration.
var loggerFactory = LoggerFactory.Create(builder => builder.AddConsole());

// Create an NpgsqlDataSourceBuilder, configuring it with our LoggerFactory
var dataSourceBuilder = new NpgsqlDataSourceBuilder("Host=localhost;Username=test;Password=test");
dataSourceBuilder.UseLoggerFactory(loggerFactory);
await using var dataSource = dataSourceBuilder.Build();

// Any connections handed out by the data source will log via the LoggerFactory:
await using var connection = await dataSource.OpenConnectionAsync();
await using var command = new NpgsqlCommand("SELECT 1", connection);
_ = await command.ExecuteScalarAsync();
```

--------------------------------

### Severity

Source: https://www.npgsql.org/doc/api/Npgsql.PostgresException.html

Gets the severity of the error or notice.

```APIDOC
## Severity

### Description
Gets the severity of the error or notice.

### Property Value
string
```

--------------------------------

### Start test_decoding replication with Npgsql

Source: https://www.npgsql.org/doc/replication.html

Opens a logical replication connection and starts replication with a TestDecodingReplicationSlot. The loop prints each message and calls SetReplicationStatus to inform the server of the last processed WAL position. Always call SetReplicationStatus or assign LastAppliedLsn/LastFlushedLsn to allow WAL cleanup.

```csharp
await using var conn = new LogicalReplicationConnection("Host=localhost;Username=test;Password=test");
await conn.Open();

var slot = new TestDecodingReplicationSlot("blog_slot");

// The following will loop until the cancellation token is triggered, and will print message types coming from PostgreSQL:
var cancellationTokenSource = new CancellationTokenSource();
await foreach (var message in conn.StartReplication(slot, cancellationTokenSource.Token))
{
    Console.WriteLine($"Message: {message.Data}");

    // Always call SetReplicationStatus() or assign LastAppliedLsn and LastFlushedLsn individually
    // so that Npgsql can inform the server which WAL files can be removed/recycled.
    conn.SetReplicationStatus(message.WalEnd);
}
```

--------------------------------

### Hint

Source: https://www.npgsql.org/doc/api/Npgsql.PostgresException.html

Gets an optional suggestion what to do about the problem.

```APIDOC
## Hint

### Description
Gets an optional suggestion what to do about the problem.

### Property Value
string (nullable)
```

--------------------------------

### ConfigureTracing(Action<NpgsqlTracingOptionsBuilder>)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataSourceBuilder.html

Configures OpenTelemetry tracing options.

```APIDOC
## ConfigureTracing(Action<NpgsqlTracingOptionsBuilder>)

### Description
Configures OpenTelemetry tracing options.

### Method
ConfigureTracing

### Parameters
- `configureAction` (Action<NpgsqlTracingOptionsBuilder>) - Required - The action to configure tracing options.

### Returns
- NpgsqlDataSourceBuilder - The same builder instance so that multiple calls can be chained.
```

--------------------------------

### NpgsqlTransaction.IsolationLevel

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlTransaction.html

Gets the isolation level for this transaction.

```APIDOC
## NpgsqlTransaction.IsolationLevel

### Description
Specifies the isolation level for this transaction.

### Property Value
- **IsolationLevel** - The isolation level for this transaction. The default is ReadCommitted.

### Syntax
```csharp
public override IsolationLevel IsolationLevel { get; }
```
```

--------------------------------

### BatchCommands

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlBatch.html

Gets the collection of batch commands.

```APIDOC
## BatchCommands Property

### Description
Gets the collection of DbBatchCommand objects.

### Property Signature
`public NpgsqlBatchCommandCollection BatchCommands { get; }`

### Property Value
- **NpgsqlBatchCommandCollection** - The commands contained within the batch.
```

--------------------------------

### NpgsqlCommand(string?)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Initializes a new instance of the NpgsqlCommand class with the text of the query.

```APIDOC
## NpgsqlCommand(string?)

### Description
Initializes a new instance of the NpgsqlCommand class with the text of the query.

### Method
Constructor

### Signature
public NpgsqlCommand(string? cmdText)

### Parameters
- **cmdText** (string) - The text of the query.

```

--------------------------------

### Transaction

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Property to get or set the transaction.

```APIDOC
## Property: Transaction

### Description
This property is ignored by Npgsql. PostgreSQL only supports a single transaction at a given time on a given connection, and all commands implicitly run inside the current transaction started via BeginTransaction().

### Property Signature
```csharp
public NpgsqlTransaction? Transaction { get; set; }
```

### Property Value
- **Type**: NpgsqlTransaction
- **Description**: The transaction associated with the command.
```

--------------------------------

### Parameters

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Property to get the parameter collection.

```APIDOC
## Property: Parameters

### Description
Gets the NpgsqlParameterCollection.

### Property Signature
```csharp
public NpgsqlParameterCollection Parameters { get; }
```

### Property Value
- **Type**: NpgsqlParameterCollection
- **Description**: The parameters of the SQL statement or function (stored procedure). The default is an empty collection.
```

--------------------------------

### Run Npgsql test suite with dotnet test

Source: https://www.npgsql.org/doc/dev/tests.html

Run the test suite for Npgsql.Tests, Npgsql.PluginTests, and Npgsql.Benchmarks from the repository root. Requires a PostgreSQL backend running locally on the default port.

```bash
cd ~/npgsql
dotnet test ./test/Npgsql.Tests
dotnet test ./test/Npgsql.PluginTests
dotnet test ./test/Npgsql.Benchmarks
```

--------------------------------

### Connection

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlCommand.html

Property to get or set the connection.

```APIDOC
## Property: Connection

### Description
Gets or sets the NpgsqlConnection used by this instance of the NpgsqlCommand.

### Property Signature
```csharp
public NpgsqlConnection? Connection { get; set; }
```

### Property Value
- **Type**: NpgsqlConnection
- **Description**: The connection to a data source. The default value is null.
```

--------------------------------

### Roundtrip a NetTopologySuite Point with Npgsql

Source: https://www.npgsql.org/doc/types/nts.html

Creates a temporary table with a GEOMETRY column, inserts a Point using a parameter, and reads it back as a Point. Demonstrates automatic type mapping between NetTopologySuite and PostGIS.

```csharp
await conn.ExecuteNonQueryAsync("CREATE TEMP TABLE data (geom GEOMETRY)");

await using (var cmd = new NpgsqlCommand("INSERT INTO data (geom) VALUES ($1)", conn))
{
    cmd.Parameters.Add(new() { Value = new Point(new Coordinate(1d, 1d)) });
    await cmd.ExecuteNonQueryAsync();
}

await using (var cmd = new NpgsqlCommand("SELECT geom FROM data", conn))
await using (var reader = await cmd.ExecuteReaderAsync())
{
    await reader.ReadAsync();
    var point = reader.GetFieldValue<Point>(0);
}
```

--------------------------------

### BeginBinaryExport(string)

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlConnection.html

Begins a binary COPY TO STDOUT operation for high-performance data export from a PostgreSQL table.

```APIDOC
## BeginBinaryExport(string)

### Description
Begins a binary COPY TO STDOUT operation, a high-performance data export mechanism from a PostgreSQL table.

### Method
BeginBinaryExport

### Signature
public NpgsqlBinaryExporter BeginBinaryExport(string copyToCommand)

### Parameters
- **copyToCommand** (string) - Required - A COPY TO STDOUT SQL command

### Returns
NpgsqlBinaryExporter - A NpgsqlBinaryExporter which can be used to read rows and columns

### Remarks
See https://www.postgresql.org/docs/current/static/sql-copy.html.
```

--------------------------------

### UpdateCommand

Source: https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataAdapter.html

Gets or sets the update command.

```APIDOC
## UpdateCommand

### Description
Gets or sets the update command.

### Syntax
```csharp
public NpgsqlCommand? UpdateCommand { get; set; }
```

### Property Value
NpgsqlCommand - The update command.

```

--------------------------------

### NpgsqlCube.ToSubset(params int[]) method

Source: https://www.npgsql.org/doc/api/NpgsqlTypes.NpgsqlCube.html

Creates a new cube from an existing cube using a list of dimension indexes. Can extract endpoints of a single dimension, drop dimensions, or reorder them.

```csharp
public NpgsqlCube ToSubset(params int[] indexes)
```
Tokens:
Raw