internal CompressedRecordPage GetCompressedRecordPage(PagePointer loc, CompressionContext compression)
{
if (compression.CompressionLevel == CompressionLevel.None)
{
throw new ArgumentException("Can't load compressed page with a compression level of none.");
}
Debug.WriteLine("Loading compressed record page " + loc);
return(new CompressedRecordPage(bufferManager.GetPageBytes(loc.FileID, loc.PageID), compression, this));
}
/// <summary>
/// Starts at the data page (loc) and follows the NextPage pointer chain till the end.
/// </summary>
internal IEnumerable <Row> ScanLinkedDataPages(PagePointer loc, Row schema, CompressionContext compression)
{
while (loc != PagePointer.Zero)
{
var recordParser = RecordEntityParser.CreateEntityParserForPage(loc, compression, Database);
foreach (var dr in recordParser.GetEntities(schema))
{
yield return(dr);
}
loc = recordParser.NextPage;
}
}
private void scanPartition(long partitionID, int partitionNumber, Row schema)
{
// Lookup partition
var partition = Database.Dmvs.Partitions
.Where(p => p.PartitionID == partitionID && p.PartitionNumber == partitionNumber)
.SingleOrDefault();
if (partition == null)
{
throw new ArgumentException("Partition (" + partitionID + "." + partitionNumber + " does not exist.");
}
// Get allocation unit for in-row data
var au = Database.Dmvs.SystemInternalsAllocationUnits
.Where(x => x.ContainerID == partition.PartitionID && x.Type == 1)
.SingleOrDefault();
if (au == null)
{
throw new ArgumentException("Partition (" + partition.PartitionID + "." + partition.PartitionNumber + " has no HOBT allocation unit.");
}
// Before we can scan either heaps or indices, we need to know the compression level as that's set at the partition level, and not at the record/page level.
// We also need to know whether the partition is using vardecimals.
var compression = new CompressionContext((CompressionLevel)partition.DataCompression, MetaData.PartitionHasVardecimalColumns(partition.PartitionID));
// Heap tables won't have root pages, thus we can check whether a root page is defined for the HOBT allocation unit
if (au.RootPage != PagePointer.Zero)
{
var Index = 0;
foreach (var row in ScanLinkedDataPages(au.FirstPage, schema, compression))
{
addRow(row, Index);
Index++;
}
}
else
{
var index = 0;
foreach (var row in scanHeap(au.FirstIamPage, schema, compression))
{
addRow(row, index);
index++;
}
}
}
/// <summary>
/// Scans a heap beginning from the provided IAM page and onwards.
/// </summary>
private IEnumerable <Row> scanHeap(PagePointer loc, Row schema, CompressionContext compression)
{
// Traverse the linked list of IAM pages untill the tail pointer is zero
while (loc != PagePointer.Zero)
{
// Before scanning, check that the IAM page itself is allocated
var pfsPage = Database.GetPfsPage(PfsPage.GetPfsPointerForPage(loc));
// If IAM page isn't allocated, there's nothing to return
if (!pfsPage.GetPageDescription(loc.PageID).IsAllocated)
{
yield break;
}
var iamPage = Database.GetIamPage(loc);
// Create an array with all of the header slot pointers
var iamPageSlots = new[]
{
iamPage.Slot0,
iamPage.Slot1,
iamPage.Slot2,
iamPage.Slot3,
iamPage.Slot4,
iamPage.Slot5,
iamPage.Slot6,
iamPage.Slot7
};
// Loop each header slot and yield the results, provided the header slot is allocated
foreach (var slot in iamPageSlots.Where(x => x != PagePointer.Zero))
{
var recordParser = RecordEntityParser.CreateEntityParserForPage(slot, compression, Database);
foreach (var dr in recordParser.GetEntities(schema))
{
yield return(dr);
}
}
// Then loop through allocated extents and yield results
foreach (var extent in iamPage.GetAllocatedExtents())
{
// Get PFS page that tracks this extent
var pfs = Database.GetPfsPage(PfsPage.GetPfsPointerForPage(extent.StartPage));
foreach (var pageLoc in extent.GetPagePointers())
{
// Check if page is allocated according to PFS page
var pfsDescription = pfs.GetPageDescription(pageLoc.PageID);
if (!pfsDescription.IsAllocated)
{
continue;
}
var recordParser = RecordEntityParser.CreateEntityParserForPage(pageLoc, compression, Database);
foreach (var dr in recordParser.GetEntities(schema))
{
yield return(dr);
}
}
}
// Update current IAM chain location to the tail pointer
loc = iamPage.Header.NextPage;
}
}
/// <summary>
/// Will scan any table - heap or clustered - and return an IEnumerable of typed rows with data & schema
/// </summary>
//internal IEnumerable<TDataRow> ScanTable<TDataRow>(string tableName) where TDataRow : Row, new()
//{
// //var schema = new TDataRow();
// //return scanTable(tableName, schema).Cast<TDataRow>();
//}
/// <summary>
/// Scans a linked list of pages returning an IEnumerable of typed rows with data & schema
/// </summary>
internal IEnumerable <TDataRow> ScanLinkedDataPages <TDataRow>(PagePointer loc, CompressionContext compression) where TDataRow : Row, new()
{
return(ScanLinkedDataPages(loc, new TDataRow(), compression).Cast <TDataRow>());
}
internal PrimaryRecordPage GetPrimaryRecordPage(PagePointer loc, CompressionContext compression)
{
Debug.WriteLine("Loading Primary Record Page " + loc);
return(new PrimaryRecordPage(bufferManager.GetPageBytes(loc.FileID, loc.PageID), compression, this));
}
/// <summary>
/// Starts at the data page (loc) and follows the NextPage pointer chain till the end.
/// </summary>
internal IEnumerable <Row> ScanLinkedNonclusteredIndexPages(PagePointer loc, Row schema, CompressionContext compression)
{
while (loc != PagePointer.Zero)
{
var page = Database.GetNonclusteredIndexPage(loc);
foreach (var dr in page.GetEntities(schema, compression))
{
yield return(dr);
}
loc = page.Header.NextPage;
}
}
