LogStore.CreateLogArchiveSnapshot Method
Definition
Important
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Takes a snapshot of the log store state necessary to make a backup.
Overloads
| CreateLogArchiveSnapshot() |
Takes a snapshot of the log store state for making a backup. |
| CreateLogArchiveSnapshot(SequenceNumber, SequenceNumber) |
Takes a snapshot of the log store state between the specified sequence numbers for making a backup. |
CreateLogArchiveSnapshot()
Takes a snapshot of the log store state for making a backup.
public:
System::IO::Log::LogArchiveSnapshot ^ CreateLogArchiveSnapshot();public System.IO.Log.LogArchiveSnapshot CreateLogArchiveSnapshot ();member this.CreateLogArchiveSnapshot : unit -> System.IO.Log.LogArchiveSnapshotPublic Function CreateLogArchiveSnapshot () As LogArchiveSnapshotReturns
A LogArchiveSnapshot object that contains the state necessary to make an archive.
Exceptions
The log store is not archivable.
The method was called after the sequence has been disposed of.
An I/O error occurs when creating the archive snapshot.
An argument is not valid.
An invalid operation has been executed.
There is not enough memory to continue the execution of a program.
The record sequence is full.
Access for the specified log store is denied by the operating system.
Examples
The following example shows how to archive a LogStore to an XML document.
class LogBackup
{
static void ArchiveToXML(LogStore logStore, string fileName)
{
LogArchiveSnapshot snapshot = logStore.CreateLogArchiveSnapshot();
XmlTextWriter writer = new XmlTextWriter(fileName, Encoding.ASCII);
writer.WriteStartElement("logArchive");
foreach(FileRegion region in snapshot.ArchiveRegions)
{
writer.WriteStartElement("fileRegion");
writer.WriteElementString("path", region.Path);
writer.WriteElementString("length", region.FileLength.ToString());
writer.WriteElementString("offset", region.Offset.ToString());
using(Stream dataStream = region.GetStream())
{
byte[] data = new byte[dataStream.Length];
dataStream.Read(data, 0, data.Length);
writer.WriteElementString("data", Convert.ToBase64String(data));
}
writer.WriteEndElement();
}
writer.WriteEndElement();
writer.Close();
logStore.SetArchiveTail(snapshot.LastSequenceNumber);
}
static void RestoreFromXML(string fileName)
{
using(XmlTextReader reader = new XmlTextReader(fileName))
{
reader.ReadStartElement("logArchive");
while(reader.IsStartElement())
{
string path = reader.ReadElementString("path");
long length = Int64.Parse(reader.ReadElementString("length"));
long offset = Int64.Parse(reader.ReadElementString("offset"));
string dataString = reader.ReadElementString("data");
byte[] data = Convert.FromBase64String(dataString);
FileStream fileStream;
using(fileStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write))
{
fileStream.SetLength(length);
fileStream.Position = offset; fileStream.Write(data, 0, data.Length);
}
}
reader.ReadEndElement();
}
}
}
Friend Class LogBackup
Private Shared Sub ArchiveToXML(ByVal logStore As LogStore, ByVal fileName As String)
Dim snapshot As LogArchiveSnapshot = logStore.CreateLogArchiveSnapshot()
Dim writer As New XmlTextWriter(fileName, Encoding.ASCII)
writer.WriteStartElement("logArchive")
For Each region As FileRegion In snapshot.ArchiveRegions
writer.WriteStartElement("fileRegion")
writer.WriteElementString("path", region.Path)
writer.WriteElementString("length", region.FileLength.ToString())
writer.WriteElementString("offset", region.Offset.ToString())
Using dataStream As Stream = region.GetStream()
Dim data(dataStream.Length - 1) As Byte
dataStream.Read(data, 0, data.Length)
writer.WriteElementString("data", Convert.ToBase64String(data))
End Using
writer.WriteEndElement()
Next region
writer.WriteEndElement()
writer.Close()
logStore.SetArchiveTail(snapshot.LastSequenceNumber)
End Sub
Private Shared Sub RestoreFromXML(ByVal fileName As String)
Using reader As New XmlTextReader(fileName)
reader.ReadStartElement("logArchive")
Do While reader.IsStartElement()
Dim path = reader.ReadElementString("path")
Dim length = Int64.Parse(reader.ReadElementString("length"))
Dim offset = Int64.Parse(reader.ReadElementString("offset"))
Dim dataString = reader.ReadElementString("data")
Dim data() = Convert.FromBase64String(dataString)
Dim fileStream As FileStream
fileStream = New FileStream(path, FileMode.OpenOrCreate, FileAccess.Write)
Using fileStream
fileStream.SetLength(length)
fileStream.Position = offset
fileStream.Write(data, 0, data.Length)
End Using
Loop
reader.ReadEndElement()
End Using
End Sub
End Class
Applies to
CreateLogArchiveSnapshot(SequenceNumber, SequenceNumber)
Takes a snapshot of the log store state between the specified sequence numbers for making a backup.
public:
System::IO::Log::LogArchiveSnapshot ^ CreateLogArchiveSnapshot(System::IO::Log::SequenceNumber first, System::IO::Log::SequenceNumber last);public System.IO.Log.LogArchiveSnapshot CreateLogArchiveSnapshot (System.IO.Log.SequenceNumber first, System.IO.Log.SequenceNumber last);member this.CreateLogArchiveSnapshot : System.IO.Log.SequenceNumber * System.IO.Log.SequenceNumber -> System.IO.Log.LogArchiveSnapshotPublic Function CreateLogArchiveSnapshot (first As SequenceNumber, last As SequenceNumber) As LogArchiveSnapshotParameters
- first
- SequenceNumber
The starting sequence number in the range to archive.
- last
- SequenceNumber
The ending sequence number in the range to archive.
Returns
A LogArchiveSnapshot object that contains the state necessary to make an archive.
Exceptions
first or last is not between the base and last sequence numbers of this sequence.
first is larger than last.
An invalid operation has been executed.
An I/O error occurs when creating the archive snapshot.
The log store is not archivable.
The method was called after the sequence has been disposed of.
There is not enough memory to continue the execution of a program.
The record sequence is full.
Access for the specified log store is denied by the operating system.
Remarks
The archive snapshot returned from this method encompasses information from either the base sequence number or the archive sequence number, whichever is lower, to the last sequence number. It is not inclusive for the last sequence number, which means that the archive only includes records up to but not including last. In addition, when using this method, the start SequenceNumber must be equal to the BaseSequenceNumber in order for the archive to be consistent.
