Struct NpgsqlLogSequenceNumber

Namespace

NpgsqlTypes

Assembly

Npgsql.dll

Wraps a PostgreSQL Write-Ahead Log Sequence Number (see: https://www.postgresql.org/docs/current/datatype-pg-lsn.html)

public readonly struct NpgsqlLogSequenceNumber : IEquatable<NpgsqlLogSequenceNumber>, IComparable<NpgsqlLogSequenceNumber>

Implements

IEquatable<NpgsqlLogSequenceNumber>

IComparable<NpgsqlLogSequenceNumber>

Inherited Members

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Remarks

Log Sequence Numbers are a fundamental concept of the PostgreSQL Write-Ahead Log and by that of PostgreSQL replication. See https://www.postgresql.org/docs/current/wal-internals.html for what they represent.

This struct provides conversions from/to string and ulong and beyond that tries to port the methods and operators in https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/utils/adt/pg_lsn.c but nothing more.

Constructors

NpgsqlLogSequenceNumber(ulong)

Initializes a new instance of NpgsqlLogSequenceNumber.

public NpgsqlLogSequenceNumber(ulong value)

Parameters

value ulong

The value to wrap.

Fields

Invalid

Zero is used indicate an invalid Log Sequence Number. No XLOG record can begin at zero.

public static readonly NpgsqlLogSequenceNumber Invalid

Field Value

NpgsqlLogSequenceNumber

Methods

CompareTo(NpgsqlLogSequenceNumber)

Compares this instance to a specified NpgsqlLogSequenceNumber and returns an indication of their relative values.

public int CompareTo(NpgsqlLogSequenceNumber value)

Parameters

value NpgsqlLogSequenceNumber

A NpgsqlLogSequenceNumber instance to compare to this instance.

Returns

int

A signed number indicating the relative values of this instance and value.

Equals(NpgsqlLogSequenceNumber)

Returns a value indicating whether this instance is equal to a specified NpgsqlLogSequenceNumber instance.

public bool Equals(NpgsqlLogSequenceNumber other)

Parameters

other NpgsqlLogSequenceNumber

A NpgsqlLogSequenceNumber instance to compare to this instance.

Returns

bool

true if the current instance is equal to the value parameter; otherwise, false.

Equals(object?)

Returns a value indicating whether this instance is equal to a specified object.

public override bool Equals(object? obj)

Parameters

obj object

An object to compare to this instance

Returns

bool

true if the current instance is equal to the value parameter; otherwise, false.

GetHashCode()

Returns the hash code for this instance.

public override int GetHashCode()

Returns

int

A 32-bit signed integer hash code.

Larger(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns the larger of two NpgsqlLogSequenceNumber values.

public static NpgsqlLogSequenceNumber Larger(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

NpgsqlLogSequenceNumber

The larger of the two NpgsqlLogSequenceNumber values.

Parse(ReadOnlySpan<char>)

Converts the span representation of a Log Sequence Number to a NpgsqlLogSequenceNumber instance.

public static NpgsqlLogSequenceNumber Parse(ReadOnlySpan<char> s)

Parameters

s ReadOnlySpan<char>

A span containing the characters that represent the Log Sequence Number to convert.

Returns

NpgsqlLogSequenceNumber

A NpgsqlLogSequenceNumber equivalent to the Log Sequence Number specified in s.

Exceptions

OverflowException

The s parameter represents a number less than MinValue or greater than MaxValue.

FormatException

The s parameter is not in the right format.

Parse(string)

Converts the string representation of a Log Sequence Number to a NpgsqlLogSequenceNumber instance.

public static NpgsqlLogSequenceNumber Parse(string s)

Parameters

s string

A string that represents the Log Sequence Number to convert.

Returns

NpgsqlLogSequenceNumber

A NpgsqlLogSequenceNumber equivalent to the Log Sequence Number specified in s.

Exceptions

ArgumentNullException

The s parameter is null.

OverflowException

The s parameter represents a number less than MinValue or greater than MaxValue.

FormatException

The s parameter is not in the right format.

Smaller(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns the smaller of two NpgsqlLogSequenceNumber values.

public static NpgsqlLogSequenceNumber Smaller(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

NpgsqlLogSequenceNumber

The smaller of the two NpgsqlLogSequenceNumber values.

ToString()

Converts the numeric value of this instance to its equivalent string representation.

public override string ToString()

Returns

string

The string representation of the value of this instance, consisting of two hexadecimal numbers of up to 8 digits each, separated by a slash

TryParse(ReadOnlySpan<char>, out NpgsqlLogSequenceNumber)

Tries to convert the span representation of a Log Sequence Number to an NpgsqlLogSequenceNumber instance. A return value indicates whether the conversion succeeded or failed.

public static bool TryParse(ReadOnlySpan<char> s, out NpgsqlLogSequenceNumber result)

Parameters

s ReadOnlySpan<char>

A span containing the characters that represent the Log Sequence Number to convert.

result NpgsqlLogSequenceNumber

When this method returns, contains a NpgsqlLogSequenceNumber instance equivalent to the Log Sequence Number contained in s, if the conversion succeeded, or the default value for NpgsqlLogSequenceNumber (0) if the conversion failed. The conversion fails if the s parameter is empty, is not in the right format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized; any value originally supplied in result will be overwritten.

Returns

bool

true if s was converted successfully; otherwise, false.

TryParse(string, out NpgsqlLogSequenceNumber)

Tries to convert the string representation of a Log Sequence Number to an NpgsqlLogSequenceNumber instance. A return value indicates whether the conversion succeeded or failed.

public static bool TryParse(string s, out NpgsqlLogSequenceNumber result)

Parameters

s string

A string that represents the Log Sequence Number to convert.

result NpgsqlLogSequenceNumber

When this method returns, contains a NpgsqlLogSequenceNumber instance equivalent to the Log Sequence Number contained in s, if the conversion succeeded, or the default value for NpgsqlLogSequenceNumber (0) if the conversion failed. The conversion fails if the s parameter is null or Empty, is not in the right format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized; any value originally supplied in result will be overwritten.

Returns

bool

true if sc> was converted successfully; otherwise, false.

Operators

operator +(NpgsqlLogSequenceNumber, double)

Add the number of bytes to a NpgsqlLogSequenceNumber instance, giving a new NpgsqlLogSequenceNumber instance. Handles both positive and negative numbers of bytes.

public static NpgsqlLogSequenceNumber operator +(NpgsqlLogSequenceNumber lsn, double nbytes)

Parameters

lsn NpgsqlLogSequenceNumber

The NpgsqlLogSequenceNumber instance representing a write-ahead log location.

nbytes double

The number of bytes to add.

Returns

NpgsqlLogSequenceNumber

A new NpgsqlLogSequenceNumber instance.

Exceptions

OverflowException

The resulting NpgsqlLogSequenceNumber instance would represent a number greater than MaxValue.

operator ==(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value that indicates whether two specified instances of NpgsqlLogSequenceNumber are equal.

public static bool operator ==(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first Log Sequence Number to compare.

value2 NpgsqlLogSequenceNumber

The second Log Sequence Number to compare.

Returns

bool

true if value1 equals value2; otherwise, false.

explicit operator ulong(NpgsqlLogSequenceNumber)

Converts the value of a NpgsqlLogSequenceNumber instance to a 64-bit unsigned integer value.

public static explicit operator ulong(NpgsqlLogSequenceNumber value)

Parameters

value NpgsqlLogSequenceNumber

A NpgsqlLogSequenceNumber instance

Returns

ulong

The contents of value as 64-bit unsigned integer.

explicit operator NpgsqlLogSequenceNumber(ulong)

Converts the value of a 64-bit unsigned integer to a NpgsqlLogSequenceNumber instance.

public static explicit operator NpgsqlLogSequenceNumber(ulong value)

Parameters

value ulong

A 64-bit unsigned integer.

Returns

NpgsqlLogSequenceNumber

A new instance of NpgsqlLogSequenceNumber initialized to value.

operator >(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value indicating whether a specified NpgsqlLogSequenceNumber instance is greater than another specified NpgsqlLogSequenceNumber instance.

public static bool operator >(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

bool

true if value1 is greater than value2; otherwise, false.

operator >=(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value indicating whether a specified NpgsqlLogSequenceNumber instance is greater than or equal to another specified NpgsqlLogSequenceNumber instance.

public static bool operator >=(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

bool

true if value1 is greater than or equal to value2; otherwise, false.

operator !=(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value that indicates whether two specified instances of NpgsqlLogSequenceNumber are not equal.

public static bool operator !=(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first Log Sequence Number to compare.

value2 NpgsqlLogSequenceNumber

The second Log Sequence Number to compare.

Returns

bool

true if value1 does not equal value2; otherwise, false.

operator <(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value indicating whether a specified NpgsqlLogSequenceNumber instance is less than another specified NpgsqlLogSequenceNumber instance.

public static bool operator <(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

bool

true if value1 is less than value2; otherwise, false.

operator <=(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Returns a value indicating whether a specified NpgsqlLogSequenceNumber instance is less than or equal to another specified NpgsqlLogSequenceNumber instance.

public static bool operator <=(NpgsqlLogSequenceNumber value1, NpgsqlLogSequenceNumber value2)

Parameters

value1 NpgsqlLogSequenceNumber

The first value to compare.

value2 NpgsqlLogSequenceNumber

The second value to compare.

Returns

bool

true if value1 is less than or equal to value2; otherwise, false.

operator -(NpgsqlLogSequenceNumber, NpgsqlLogSequenceNumber)

Subtracts two specified NpgsqlLogSequenceNumber values.

public static ulong operator -(NpgsqlLogSequenceNumber first, NpgsqlLogSequenceNumber second)

Parameters

first NpgsqlLogSequenceNumber

The first NpgsqlLogSequenceNumber value.

second NpgsqlLogSequenceNumber

The second NpgsqlLogSequenceNumber value.

Returns

ulong

The number of bytes separating those write-ahead log locations.

operator -(NpgsqlLogSequenceNumber, double)

Subtract the number of bytes from a NpgsqlLogSequenceNumber instance, giving a new NpgsqlLogSequenceNumber instance. Handles both positive and negative numbers of bytes.

public static NpgsqlLogSequenceNumber operator -(NpgsqlLogSequenceNumber lsn, double nbytes)

Parameters

lsn NpgsqlLogSequenceNumber

The NpgsqlLogSequenceNumber instance representing a write-ahead log location.

nbytes double

The number of bytes to subtract.

Returns

NpgsqlLogSequenceNumber

A new NpgsqlLogSequenceNumber instance.

Exceptions

OverflowException

The resulting NpgsqlLogSequenceNumber instance would represent a number less than MinValue.