/// <summary>

/// Represents a SQL statement or function (stored procedure) to execute

/// against a PostgreSQL database. This class cannot be inherited.

/// </summary>

// ReSharper disable once RedundantNameQualifier

[System.ComponentModel.DesignerCategory("")]

public sealed class NpgsqlCommand : DbCommand, ICloneable

{

#region Fields

NpgsqlConnection? _connection;

/// <summary>

/// If this command is (explicitly) prepared, references the connector on which the preparation happened.

/// Used to detect when the connector was changed (i.e. connection open/close), meaning that the command

/// is no longer prepared.

/// </summary>

NpgsqlConnector? _connectorPreparedOn;

string? _commandText;

int? _timeout;

readonly NpgsqlParameterCollection _parameters;

readonly List<NpgsqlStatement> _statements;

/// <summary>

/// Returns details about each statement that this command has executed.

/// Is only populated when an Execute* method is called.

/// </summary>

public IReadOnlyList<NpgsqlStatement> Statements => _statements.AsReadOnly();

UpdateRowSource _updateRowSource = UpdateRowSource.Both;

bool IsExplicitlyPrepared => _connectorPreparedOn != null;

static readonly List<NpgsqlParameter> EmptyParameters = new List<NpgsqlParameter>();

static readonly SingleThreadSynchronizationContext SingleThreadSynchronizationContext = new SingleThreadSynchronizationContext("NpgsqlRemainingAsyncSendWorker");

static readonly NpgsqlLogger Log = NpgsqlLogManager.CreateLogger(nameof(NpgsqlCommand));

#endregion Fields

#region Constants

internal const int DefaultTimeout = 30;

#endregion

#region Constructors

#nullable disable

/// <summary>

/// Initializes a new instance of the <see cref="NpgsqlCommand">NpgsqlCommand</see> class.

/// </summary>

public NpgsqlCommand() : this(null, null, null) {}

/// <summary>

/// Initializes a new instance of the <see cref="NpgsqlCommand">NpgsqlCommand</see> class with the text of the query.

/// </summary>

/// <param name="cmdText">The text of the query.</param>

// ReSharper disable once IntroduceOptionalParameters.Global

public NpgsqlCommand(string cmdText) : this(cmdText, null, null) {}

/// <summary>

/// Initializes a new instance of the <see cref="NpgsqlCommand">NpgsqlCommand</see> class with the text of the query and a <see cref="NpgsqlConnection">NpgsqlConnection</see>.

/// </summary>

/// <param name="cmdText">The text of the query.</param>

/// <param name="connection">A <see cref="NpgsqlConnection">NpgsqlConnection</see> that represents the connection to a PostgreSQL server.</param>

// ReSharper disable once IntroduceOptionalParameters.Global

public NpgsqlCommand(string cmdText, NpgsqlConnection connection) : this(cmdText, connection, null) {}

/// <summary>

/// Initializes a new instance of the <see cref="NpgsqlCommand">NpgsqlCommand</see> class with the text of the query, a <see cref="NpgsqlConnection">NpgsqlConnection</see>, and the <see cref="NpgsqlTransaction">NpgsqlTransaction</see>.

/// </summary>

/// <param name="cmdText">The text of the query.</param>

/// <param name="connection">A <see cref="NpgsqlConnection">NpgsqlConnection</see> that represents the connection to a PostgreSQL server.</param>

/// <param name="transaction">The <see cref="NpgsqlTransaction">NpgsqlTransaction</see> in which the <see cref="NpgsqlCommand">NpgsqlCommand</see> executes.</param>

public NpgsqlCommand(string cmdText, NpgsqlConnection connection, NpgsqlTransaction transaction)

{

GC.SuppressFinalize(this);

_statements = new List<NpgsqlStatement>(1);

_parameters = new NpgsqlParameterCollection();

_commandText = cmdText;

_connection = connection;

Transaction = transaction;

CommandType = CommandType.Text;

}

#endregion Constructors

#region Public properties

/// <summary>

/// Gets or sets the SQL statement or function (stored procedure) to execute at the data source.

/// </summary>

/// <value>The Transact-SQL statement or stored procedure to execute. The default is an empty string.</value>

[DefaultValue("")]

[Category("Data")]

public override string CommandText

{

get => _commandText;

set

{

_commandText = State == CommandState.Idle

? value

: throw new InvalidOperationException("An open data reader exists for this command.");

ResetExplicitPreparation();

// TODO: Technically should do this also if the parameter list (or type) changes

}

}

#nullable restore

/// <summary>

/// Gets or sets the wait time (in seconds) before terminating the attempt to execute a command and generating an error.

/// </summary>

/// <value>The time (in seconds) to wait for the command to execute. The default value is 30 seconds.</value>

[DefaultValue(DefaultTimeout)]

public override int CommandTimeout

{

get => _timeout ?? (_connection?.CommandTimeout ?? DefaultTimeout);

set

{

if (value < 0) {

throw new ArgumentOutOfRangeException(nameof(value), value, "CommandTimeout can't be less than zero.");

}

_timeout = value;

}

}

/// <summary>

/// Gets or sets a value indicating how the

/// <see cref="NpgsqlCommand.CommandText">CommandText</see> property is to be interpreted.

/// </summary>

/// <value>One of the <see cref="System.Data.CommandType">CommandType</see> values. The default is <see cref="System.Data.CommandType">CommandType.Text</see>.</value>

[DefaultValue(CommandType.Text)]

[Category("Data")]

public override CommandType CommandType { get; set; }

/// <summary>

/// DB connection.

/// </summary>

protected override DbConnection? DbConnection

{

get => _connection;

set => _connection = (NpgsqlConnection?)value;

}

/// <summary>

/// Gets or sets the <see cref="NpgsqlConnection">NpgsqlConnection</see>

/// used by this instance of the <see cref="NpgsqlCommand">NpgsqlCommand</see>.

/// </summary>

/// <value>The connection to a data source. The default value is a null reference.</value>

[DefaultValue(null)]

[Category("Behavior")]

public new NpgsqlConnection? Connection

{

get => _connection;

set

{

if (_connection == value)

return;

_connection = State == CommandState.Idle

? value

: throw new InvalidOperationException("An open data reader exists for this command.");

Transaction = null;

}

}

/// <summary>

/// Design time visible.

/// </summary>

public override bool DesignTimeVisible { get; set; }

/// <summary>

/// Gets or sets how command results are applied to the DataRow when used by the

/// DbDataAdapter.Update(DataSet) method.

/// </summary>

/// <value>One of the <see cref="System.Data.UpdateRowSource">UpdateRowSource</see> values.</value>

[Category("Behavior"), DefaultValue(UpdateRowSource.Both)]

public override UpdateRowSource UpdatedRowSource

{

get => _updateRowSource;

set

{

switch (value)

{

// validate value (required based on base type contract)

case UpdateRowSource.None:

case UpdateRowSource.OutputParameters:

case UpdateRowSource.FirstReturnedRecord:

case UpdateRowSource.Both:

_updateRowSource = value;

break;

default:

throw new ArgumentOutOfRangeException();

}

}

}

/// <summary>

/// Returns whether this query will execute as a prepared (compiled) query.

/// </summary>

public bool IsPrepared =>

_connectorPreparedOn == _connection?.Connector &&

_statements.Any() && _statements.All(s => s.PreparedStatement?.IsPrepared == true);

#endregion Public properties

#region Known/unknown Result Types Management

/// <summary>

/// Marks all of the query's result columns as either known or unknown.

/// Unknown results column are requested them from PostgreSQL in text format, and Npgsql makes no

/// attempt to parse them. They will be accessible as strings only.

/// </summary>

public bool AllResultTypesAreUnknown

{

get => _allResultTypesAreUnknown;

set

{

// TODO: Check that this isn't modified after calling prepare

_unknownResultTypeList = null;

_allResultTypesAreUnknown = value;

}

}

bool _allResultTypesAreUnknown;

/// <summary>

/// Marks the query's result columns as known or unknown, on a column-by-column basis.

/// Unknown results column are requested them from PostgreSQL in text format, and Npgsql makes no

/// attempt to parse them. They will be accessible as strings only.

/// </summary>

/// <remarks>

/// If the query includes several queries (e.g. SELECT 1; SELECT 2), this will only apply to the first

/// one. The rest of the queries will be fetched and parsed as usual.

///

/// The array size must correspond exactly to the number of result columns the query returns, or an

/// error will be raised.

/// </remarks>

public bool[]? UnknownResultTypeList

{

get => _unknownResultTypeList;

set

{

// TODO: Check that this isn't modified after calling prepare

_allResultTypesAreUnknown = false;

_unknownResultTypeList = value;

}

}

bool[]? _unknownResultTypeList;

#endregion

#region Result Types Management

/// <summary>

/// Marks result types to be used when using GetValue on a data reader, on a column-by-column basis.

/// Used for Entity Framework 5-6 compability.

/// Only primitive numerical types and DateTimeOffset are supported.

/// Set the whole array or just a value to null to use default type.

/// </summary>

internal Type[]? ObjectResultTypes { get; set; }

#endregion

#region State management

int _state;

/// <summary>

/// Gets the current state of the connector

/// </summary>

internal CommandState State

{

private get { return (CommandState)_state; }

set

{

var newState = (int)value;

if (newState == _state)

return;

Interlocked.Exchange(ref _state, newState);

}

}

void ResetExplicitPreparation() => _connectorPreparedOn = null;

#endregion State management

#region Parameters

/// <summary>

/// Creates a new instance of an <see cref="System.Data.Common.DbParameter">DbParameter</see> object.

/// </summary>

/// <returns>An <see cref="System.Data.Common.DbParameter">DbParameter</see> object.</returns>

protected override DbParameter CreateDbParameter()

{

return CreateParameter();

}

/// <summary>

/// Creates a new instance of a <see cref="NpgsqlParameter">NpgsqlParameter</see> object.

/// </summary>

/// <returns>A <see cref="NpgsqlParameter">NpgsqlParameter</see> object.</returns>

public new NpgsqlParameter CreateParameter()

{

return new NpgsqlParameter();

}

/// <summary>

/// DB parameter collection.

/// </summary>

protected override DbParameterCollection DbParameterCollection => Parameters;

/// <summary>

/// Gets the <see cref="NpgsqlParameterCollection">NpgsqlParameterCollection</see>.

/// </summary>

/// <value>The parameters of the SQL statement or function (stored procedure). The default is an empty collection.</value>

public new NpgsqlParameterCollection Parameters => _parameters;

#endregion

#region DeriveParameters

const string DeriveParametersForFunctionQuery = @"

internal void DeriveParameters()

{

if (Statements.Any(s => s.PreparedStatement?.IsExplicit == true))

throw new NpgsqlException("Deriving parameters isn't supported for commands that are already prepared.");

// Here we unprepare statements that possibly are auto-prepared

Unprepare();

Parameters.Clear();

if (CommandType == CommandType.StoredProcedure)

DeriveParametersForFunction();

else if (CommandType == CommandType.Text)

DeriveParametersForQuery();

}

void DeriveParametersForFunction()

{

using var c = new NpgsqlCommand(DeriveParametersForFunctionQuery, _connection);

c.Parameters.Add(new NpgsqlParameter("proname", NpgsqlDbType.Text));

c.Parameters[0].Value = CommandText;

string[]? names = null;

uint[]? types = null;

char[]? modes = null;

using (var rdr = c.ExecuteReader(CommandBehavior.SingleRow | CommandBehavior.SingleResult))

{

if (rdr.Read())

{

if (!rdr.IsDBNull(0))

names = rdr.GetFieldValue<string[]>(0);

if (!rdr.IsDBNull(2))

types = rdr.GetFieldValue<uint[]>(2);

if (!rdr.IsDBNull(3))

modes = rdr.GetFieldValue<char[]>(3);

if (types == null)

{

if (rdr.IsDBNull(1) || rdr.GetFieldValue<uint[]>(1).Length == 0)

return; // Parameter-less function

types = rdr.GetFieldValue<uint[]>(1);

}

}

else

throw new InvalidOperationException($"{CommandText} does not exist in pg_proc");

}

var typeMapper = c._connection!.Connector!.TypeMapper;

for (var i = 0; i < types.Length; i++)

{

var param = new NpgsqlParameter();

var (npgsqlDbType, postgresType) = typeMapper.GetTypeInfoByOid(types[i]);

param.DataTypeName = postgresType.DisplayName;

param.PostgresType = postgresType;

if (npgsqlDbType.HasValue)

param.NpgsqlDbType = npgsqlDbType.Value;

if (names != null && i < names.Length)

param.ParameterName = names[i];

else

param.ParameterName = "parameter" + (i + 1);

if (modes == null) // All params are IN, or server < 8.1.0 (and only IN is supported)

param.Direction = ParameterDirection.Input;

else

{

param.Direction = modes[i] switch

{

'i' => ParameterDirection.Input,

'o' => ParameterDirection.Output,

't' => ParameterDirection.Output,

'b' => ParameterDirection.InputOutput,

'v' => throw new NotSupportedException("Cannot derive function parameter of type VARIADIC"),

_ => throw new ArgumentOutOfRangeException("Unknown code in proargmodes while deriving: " + modes[i])

};

}

Parameters.Add(param);

}

}

void DeriveParametersForQuery()

{

var connector = CheckReadyAndGetConnector();

using (connector.StartUserAction())

{

Log.Debug($"Deriving Parameters for query: {CommandText}", connector.Id);

ProcessRawQuery(true);

var sendTask = SendDeriveParameters(connector, false);

foreach (var statement in _statements)

{

Expect<ParseCompleteMessage>(connector.ReadMessage(), connector);

var paramTypeOIDs = Expect<ParameterDescriptionMessage>(connector.ReadMessage(), connector).TypeOIDs;

if (statement.InputParameters.Count != paramTypeOIDs.Count)

{

connector.SkipUntil(BackendMessageCode.ReadyForQuery);

Parameters.Clear();

throw new NpgsqlException("There was a mismatch in the number of derived parameters between the Npgsql SQL parser and the PostgreSQL parser. Please report this as bug to the Npgsql developers (https://github.com/npgsql/npgsql/issues).");

}

for (var i = 0; i < paramTypeOIDs.Count; i++)

{

try

{

var param = statement.InputParameters[i];

var paramOid = paramTypeOIDs[i];

var (npgsqlDbType, postgresType) = connector.TypeMapper.GetTypeInfoByOid(paramOid);

if (param.NpgsqlDbType != NpgsqlDbType.Unknown && param.NpgsqlDbType != npgsqlDbType)

throw new NpgsqlException("The backend parser inferred different types for parameters with the same name. Please try explicit casting within your SQL statement or batch or use different placeholder names.");

param.DataTypeName = postgresType.DisplayName;

param.PostgresType = postgresType;

if (npgsqlDbType.HasValue)

param.NpgsqlDbType = npgsqlDbType.Value;

}

catch

{

connector.SkipUntil(BackendMessageCode.ReadyForQuery);

Parameters.Clear();

throw;

}

}

var msg = connector.ReadMessage();

switch (msg.Code)

{

case BackendMessageCode.RowDescription:

case BackendMessageCode.NoData:

break;

default:

throw connector.UnexpectedMessageReceived(msg.Code);

}

}

Expect<ReadyForQueryMessage>(connector.ReadMessage(), connector);

sendTask.GetAwaiter().GetResult();

}

}

#endregion

#region Prepare

/// <summary>

/// Creates a server-side prepared statement on the PostgreSQL server.

/// This will make repeated future executions of this command much faster.

/// </summary>

public override void Prepare() => Prepare(false).GetAwaiter().GetResult();

/// <summary>

/// Creates a server-side prepared statement on the PostgreSQL server.

/// This will make repeated future executions of this command much faster.

/// </summary>

/// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is <see cref="CancellationToken.None"/>.</param>

#if !NET461 && !NETSTANDARD2_0

public override Task PrepareAsync(CancellationToken cancellationToken = default)

#else

public Task PrepareAsync(CancellationToken cancellationToken = default)

#endif

{

if (cancellationToken.IsCancellationRequested)

return Task.FromCanceled(cancellationToken);

using (NoSynchronizationContextScope.Enter())

return Prepare(true);

}

Task Prepare(bool async)

{

var connector = CheckReadyAndGetConnector();

for (var i = 0; i < Parameters.Count; i++)

Parameters[i].Bind(connector.TypeMapper);

ProcessRawQuery();

Log.Debug($"Preparing: {CommandText}", connector.Id);

var needToPrepare = false;

foreach (var statement in _statements)

{

if (statement.IsPrepared)

continue;

statement.PreparedStatement = connector.PreparedStatementManager.GetOrAddExplicit(statement);

if (statement.PreparedStatement?.State == PreparedState.NotPrepared)

{

statement.PreparedStatement.State = PreparedState.ToBePrepared;

needToPrepare = true;

}

}

_connectorPreparedOn = connector;

// It's possible the command was already prepared, or that persistent prepared statements were found for

// all statements. Nothing to do here, move along.

return needToPrepare

? PrepareLong()

: Task.CompletedTask;

async Task PrepareLong()

{

using (connector.StartUserAction())

{

var sendTask = SendPrepare(connector, async);

// Loop over statements, skipping those that are already prepared (because they were persisted)

var isFirst = true;

foreach (var statement in _statements)

{

if (statement.PreparedStatement?.State == PreparedState.BeingPrepared)

{

var pStatement = statement.PreparedStatement;

if (pStatement.StatementBeingReplaced != null)

{

Expect<CloseCompletedMessage>(await connector.ReadMessage(async), connector);

pStatement.StatementBeingReplaced.CompleteUnprepare();

pStatement.StatementBeingReplaced = null;

}

Expect<ParseCompleteMessage>(await connector.ReadMessage(async), connector);

Expect<ParameterDescriptionMessage>(await connector.ReadMessage(async), connector);

var msg = await connector.ReadMessage(async);

switch (msg.Code)

{

case BackendMessageCode.RowDescription:

// Clone the RowDescription for use with the prepared statement (the one we have is reused

// by the connection)

var description = ((RowDescriptionMessage)msg).Clone();

FixupRowDescription(description, isFirst);

statement.Description = description;

break;

case BackendMessageCode.NoData:

statement.Description = null;

break;

default:

throw connector.UnexpectedMessageReceived(msg.Code);

}

pStatement.CompletePrepare();

isFirst = false;

}

}

Expect<ReadyForQueryMessage>(await connector.ReadMessage(async), connector);

if (async)

await sendTask;

else

sendTask.GetAwaiter().GetResult();

}

}

}

/// <summary>

/// Unprepares a command, closing server-side statements associated with it.

/// Note that this only affects commands explicitly prepared with <see cref="Prepare()"/>, not

/// automatically prepared statements.

/// </summary>

public void Unprepare()

{

if (_statements.All(s => !s.IsPrepared))

return;

var connector = CheckReadyAndGetConnector();

Log.Debug("Closing command's prepared statements", connector.Id);

using (connector.StartUserAction())

{

var sendTask = SendClose(connector, false);

foreach (var statement in _statements)

if (statement.PreparedStatement?.State == PreparedState.BeingUnprepared)

{

Expect<CloseCompletedMessage>(connector.ReadMessage(), connector);

statement.PreparedStatement.CompleteUnprepare();

statement.PreparedStatement = null;

}

Expect<ReadyForQueryMessage>(connector.ReadMessage(), connector);

sendTask.GetAwaiter().GetResult();

}

}

#endregion Prepare

#region Query analysis

void ProcessRawQuery(bool deriveParameters = false)

{

if (string.IsNullOrEmpty(CommandText))

throw new InvalidOperationException("CommandText property has not been initialized");

NpgsqlStatement statement;

switch (CommandType) {

case CommandType.Text:

_connection!.Connector!.SqlParser.ParseRawQuery(CommandText, _parameters, _statements, deriveParameters);

if (_statements.Count > 1 && _parameters.HasOutputParameters)

throw new NotSupportedException("Commands with multiple queries cannot have out parameters");

break;

case CommandType.TableDirect:

if (_statements.Count == 0)

statement = new NpgsqlStatement();

else

{

statement = _statements[0];

statement.Reset();

_statements.Clear();

}

_statements.Add(statement);

statement.SQL = "SELECT * FROM " + CommandText;

break;

case CommandType.StoredProcedure:

var inputList = _parameters.Where(p => p.IsInputDirection).ToList();

var numInput = inputList.Count;

var sb = new StringBuilder();

sb.Append("SELECT * FROM ");

sb.Append(CommandText);

sb.Append('(');

var hasWrittenFirst = false;

for (var i = 1; i <= numInput; i++) {

var param = inputList[i - 1];

if (param.TrimmedName == "")

{

if (hasWrittenFirst)

sb.Append(',');

sb.Append('$');

sb.Append(i);

hasWrittenFirst = true;

}

}

for (var i = 1; i <= numInput; i++)

{

var param = inputList[i - 1];

if (param.TrimmedName != "")

{

if (hasWrittenFirst)

sb.Append(',');

sb.Append('"');

sb.Append(param.TrimmedName.Replace("\"", "\"\""));

sb.Append("\" := ");

sb.Append('$');

sb.Append(i);

hasWrittenFirst = true;

}

}

sb.Append(')');

if (_statements.Count == 0)

statement = new NpgsqlStatement();

else

{

statement = _statements[0];

statement.Reset();

_statements.Clear();

}

statement.SQL = sb.ToString();

statement.InputParameters.AddRange(inputList);

_statements.Add(statement);

break;

default:

throw new InvalidOperationException($"Internal Npgsql bug: unexpected value {CommandType} of enum {nameof(CommandType)}. Please file a bug.");

}

foreach (var s in _statements)

if (s.InputParameters.Count > short.MaxValue)

throw new NpgsqlException($"A statement cannot have more than {short.MaxValue} parameters");

}

#endregion

#region Execute

void ValidateParameters(ConnectorTypeMapper typeMapper)

{

for (var i = 0; i < Parameters.Count; i++)

{

var p = Parameters[i];

if (!p.IsInputDirection)

continue;

p.Bind(typeMapper);

p.LengthCache?.Clear();

p.ValidateAndGetLength();

}

}

#endregion

#region Message Creation / Population

internal bool FlushOccurred { get; set; }

void BeginSend()

{

_connection!.Connector!.WriteBuffer.CurrentCommand = this;

FlushOccurred = false;

}

void CleanupSend()

{

// ReSharper disable once ConditionIsAlwaysTrueOrFalse

if (SynchronizationContext.Current != null) // Check first because SetSynchronizationContext allocates

SynchronizationContext.SetSynchronizationContext(null);

}

async Task SendExecute(NpgsqlConnector connector, bool async)

{

BeginSend();

for (var i = 0; i < _statements.Count; i++)

{

async = ForceAsyncIfNecessary(async, i);

var statement = _statements[i];

var pStatement = statement.PreparedStatement;

if (pStatement == null || pStatement.State == PreparedState.ToBePrepared)

{

// We may have a prepared statement that replaces an existing statement - close the latter first.

if (pStatement?.StatementBeingReplaced != null)

await connector.WriteClose(StatementOrPortal.Statement, pStatement.StatementBeingReplaced.Name!, async);

await connector.WriteParse(statement.SQL, statement.StatementName, statement.InputParameters, async);

}

await connector.WriteBind(

statement.InputParameters, string.Empty, statement.StatementName, AllResultTypesAreUnknown,

i == 0 ? UnknownResultTypeList : null,

async);

if (pStatement == null || pStatement.State == PreparedState.ToBePrepared)

{

await connector.WriteDescribe(StatementOrPortal.Portal, string.Empty, async);

if (statement.PreparedStatement != null)

statement.PreparedStatement.State = PreparedState.BeingPrepared;

}

await connector.WriteExecute(0, async);

if (pStatement != null)

pStatement.LastUsed = DateTime.UtcNow;

}

await connector.WriteSync(async);

await connector.Flush(async);

CleanupSend();

}

async Task SendExecuteSchemaOnly(NpgsqlConnector connector, bool async)

{

BeginSend();

var wroteSomething = false;

for (var i = 0; i < _statements.Count; i++)

{

async = ForceAsyncIfNecessary(async, i);

var statement = _statements[i];

if (statement.PreparedStatement?.State == PreparedState.Prepared)

continue; // Prepared, we already have the RowDescription

Debug.Assert(statement.PreparedStatement == null);

await connector.WriteParse(statement.SQL, string.Empty, statement.InputParameters, async);

await connector.WriteDescribe(StatementOrPortal.Statement, statement.StatementName, async);

wroteSomething = true;

}

if (wroteSomething)

{

await connector.WriteSync(async);

await connector.Flush(async);

}

CleanupSend();

}

async Task SendDeriveParameters(NpgsqlConnector connector, bool async)

{

BeginSend();

for (var i = 0; i < _statements.Count; i++)

{

async = ForceAsyncIfNecessary(async, i);

var statement = _statements[i];

await connector.WriteParse(statement.SQL, string.Empty, EmptyParameters, async);

await connector.WriteDescribe(StatementOrPortal.Statement, string.Empty, async);

}

await connector.WriteSync(async);

await connector.Flush(async);

CleanupSend();

}

async Task SendPrepare(NpgsqlConnector connector, bool async)

{

BeginSend();

for (var i = 0; i < _statements.Count; i++)

{

async = ForceAsyncIfNecessary(async, i);

var statement = _statements[i];

var pStatement = statement.PreparedStatement;

// A statement may be already prepared, already in preparation (i.e. same statement twice

// in the same command), or we can't prepare (overloaded SQL)

if (pStatement?.State != PreparedState.ToBePrepared)

continue;

// We may have a prepared statement that replaces an existing statement - close the latter first.

var statementToClose = pStatement.StatementBeingReplaced;

if (statementToClose != null)

await connector.WriteClose(StatementOrPortal.Statement, statementToClose.Name!, async);

await connector.WriteParse(statement.SQL, pStatement.Name!, statement.InputParameters, async);

await connector.WriteDescribe(StatementOrPortal.Statement, pStatement.Name!, async);

pStatement.State = PreparedState.BeingPrepared;

}

await connector.WriteSync(async);

await connector.Flush(async);

CleanupSend();

}

bool ForceAsyncIfNecessary(bool async, int numberOfStatementInBatch)

{

if (!async && FlushOccurred && numberOfStatementInBatch > 0)

{

// We're synchronously sending the non-first statement in a batch and a flush

// has already occured. Switch to async. See long comment in Execute() above.

async = true;

SynchronizationContext.SetSynchronizationContext(SingleThreadSynchronizationContext);

}

return async;

}

async Task SendClose(NpgsqlConnector connector, bool async)

{

BeginSend();

foreach (var statement in _statements.Where(s => s.IsPrepared))

{

if (FlushOccurred)

{

async = true;

SynchronizationContext.SetSynchronizationContext(SingleThreadSynchronizationContext);

}

await connector.WriteClose(StatementOrPortal.Statement, statement.StatementName, async);

statement.PreparedStatement!.State = PreparedState.BeingUnprepared;

}

await connector.WriteSync(async);

await connector.Flush(async);

CleanupSend();