private static void LoadCompressionInfo(CompressionInformation ci)
{
ci.StatusBits = new BitArray(new byte[] { ci.Page.PageData[ci.SlotOffset] });
ci.Mark("StatusDescription", ci.SlotOffset, 1);
ci.HasAnchorRecord = ci.StatusBits[1];
ci.HasDictionary = ci.StatusBits[2];
ci.PageModCount = BitConverter.ToInt16(ci.Page.PageData, ci.SlotOffset + 1);
ci.Mark("PageModCount", ci.SlotOffset + sizeof(byte), sizeof(short));
ci.Length = BitConverter.ToInt16(ci.Page.PageData, ci.SlotOffset + 3);
ci.Mark("Length", ci.SlotOffset + sizeof(byte) + sizeof(short), sizeof(short));
if (ci.HasDictionary)
{
ci.Size = BitConverter.ToInt16(ci.Page.PageData, ci.SlotOffset + 5);
ci.Mark("Size", ci.SlotOffset + sizeof(byte) + sizeof(short) + sizeof(short), sizeof(short));
}
if (ci.HasAnchorRecord)
{
LoadAnchor(ci);
}
if (ci.HasDictionary)
{
LoadDictionary(ci);
}
}
private static void LoadAnchor(CompressionInformation ci)
{
var startOffset = (ci.HasDictionary ? 7 : 5) + ci.SlotOffset;
int records = ci.Page.PageData[startOffset + 1];
var structure = CreateTableStructure(records, ci);
ci.AnchorRecord = new CompressedDataRecord(ci.Page, (ushort)startOffset, structure);
}
private static TableStructure CreateTableStructure(int records, CompressionInformation ci)
{
var structure = new TableStructure(ci.Page.Header.AllocationUnitId, ci.Page.Database);
var fields = new List <RecordField>();
for (short i = 0; i < records; i++)
{
var column = new Column();
column.ColumnName = $"Column {i}";
column.ColumnId = i;
column.LeafOffset = i;
column.DataType = SqlDbType.VarBinary;
column.DataLength = 8000;
structure.Columns.Add(column);
}
return(structure);
}
private static void LoadDictionary(CompressionInformation ci)
{
ci.CompressionDictionary = new Dictionary(ci.Page.PageData, Offset + ci.Length);
}