/// <summary>
/// Generate partitions based on table statistics.
/// </summary>
/// <param name="partitionCount"></param>
/// <param name="stat"></param>
private void GeneratePartitions(int partitionCount, SqlParser.TableStatistics stat)
{
SqlQueryPartition qp = null;
int s = stat.KeyValue.Count / partitionCount;
if (s == 0)
{
qp = new SqlQueryPartition(this, this.Context);
qp.PartitioningKeyFrom = double.NegativeInfinity;
qp.PartitioningKeyTo = double.PositiveInfinity;
AppendPartition(qp);
}
else
{
for (int i = 0; i < partitionCount; i++)
{
qp = new SqlQueryPartition(this, this.Context);
qp.PartitioningKeyTo = stat.KeyValue[Math.Min((i + 1) * s, stat.KeyValue.Count - 1)];
if (i == 0)
{
qp.PartitioningKeyFrom = double.NegativeInfinity;
}
else
{
qp.PartitioningKeyFrom = Partitions[i - 1].PartitioningKeyTo;
}
AppendPartition(qp);
}
Partitions[Partitions.Count - 1].PartitioningKeyTo = double.PositiveInfinity;
}
}
public override void GeneratePartitions(int partitionCount)
{
// Partitioning is only supperted using Graywulf mode, single server mode always
// falls back to a single partition
switch (ExecutionMode)
{
case ExecutionMode.SingleServer:
{
var sqp = new SqlQueryPartition(this, null);
AppendPartition(sqp);
}
break;
case ExecutionMode.Graywulf:
if (!SelectStatement.IsPartitioned)
{
var sqp = new SqlQueryPartition(this, this.Context);
AppendPartition(sqp);
}
else
{
// --- determine partition limits based on the first table's statistics
if (TableStatistics == null || TableStatistics.Count == 0)
{
throw new InvalidOperationException();
}
var stat = TableStatistics[0].Statistics;
GeneratePartitions(partitionCount, stat);
}
break;
default:
throw new NotImplementedException();
}
}
private void CopyMembers(SqlQueryPartition old)
{
}
public SqlQueryPartition(SqlQueryPartition old)
: base(old)
{
CopyMembers(old);
}
private void CopyMembers(SqlQueryPartition old)
{
}
public SqlQueryPartition(SqlQueryPartition old)
: base(old)
{
CopyMembers(old);
}
public override void GeneratePartitions(int partitionCount)
{
// Partitioning is only supperted using Graywulf mode, single server mode always
// falls back to a single partition
switch (ExecutionMode)
{
case ExecutionMode.SingleServer:
{
SqlQueryPartition sqp = new SqlQueryPartition(this, null);
sqp.ID = 0;
AppendPartition(sqp);
}
break;
case ExecutionMode.Graywulf:
if (!SelectStatement.IsPartitioned)
{
SqlQueryPartition sqp = new SqlQueryPartition(this, this.Context);
sqp.ID = 0;
AppendPartition(sqp);
}
else
{
// --- determine partition limits based on the first table's statistics
if (TableStatistics == null || TableStatistics.Count == 0)
{
throw new InvalidOperationException();
}
var stat = TableStatistics[0].Statistics;
GeneratePartitions(partitionCount, stat);
}
break;
default:
throw new NotImplementedException();
}
}
public override void GeneratePartitions(int partitionCount)
{
// Partitioning is only supperted using Graywulf mode, single server mode always
// falls back to a single partition
switch (ExecutionMode)
{
case ExecutionMode.SingleServer:
{
SqlQueryPartition sqp = new SqlQueryPartition(this, null);
sqp.ID = 0;
AppendPartition(sqp);
}
break;
case ExecutionMode.Graywulf:
if (!SelectStatement.IsPartitioned)
{
SqlQueryPartition sqp = new SqlQueryPartition(this, this.Context);
sqp.ID = 0;
AppendPartition(sqp);
}
else
{
// --- compute table statistics
decimal binsize = 1.0m; // histogram bin size in Dec
TableStatistics stat;
// Partitioning is always done on the table specified right after the FROM keyword
// TODO: what if more than one SQ?
var qs = SelectStatement.EnumerateQuerySpecifications().FirstOrDefault();
// *** TODO: test this here, will not work with functions etc!
var ats = qs.EnumerateTableSources(false).First();
var ts = ats.FindDescendant<TableSource>();
// **** tweak this to get appropriate histogram resolution and be compatible with small search areas with few object
/*do
{
stat = ComputeTableStatistics(qs, ts, binsize);
if (stat.BinCount.Count == 0) break;
binsize /= 10.0m;
}
while (stat.BinCount.Count / partitionCount < 10 && binsize > 0);*/
stat = ComputeTableStatistics(qs, ts, binsize);
// --- determine partition limits based on the first table's statistics
SqlQueryPartition qp = null;
int cnt = 0;
int bin = 0;
while (bin < stat.BinCount.Count)
{
if (qp == null)
{
cnt = 0;
qp = new SqlQueryPartition(this, this.Context);
qp.ID = Partitions.Count;
qp.PartitioningKeyFrom = (double)stat.BinMin[bin];
}
cnt += stat.BinCount[bin];
if (cnt >= (int)(stat.RowCount / (double)partitionCount) || (bin == stat.BinCount.Count - 1))
{
qp.PartitioningKeyTo = (double)stat.BinMax[bin];
AppendPartition(qp);
qp = null;
}
bin++;
}
}
break;
default:
throw new NotImplementedException();
}
}
private void GeneratePartitions(int partitionCount, SqlParser.TableStatistics stat)
{
SqlQueryPartition qp = null;
int s = stat.KeyValue.Count / partitionCount;
for (int i = 0; i < partitionCount; i++)
{
qp = new SqlQueryPartition(this, this.Context);
qp.ID = Partitions.Count;
qp.PartitioningKeyTo = stat.KeyValue[(i + 1) * s];
if (i == 0)
{
qp.PartitioningKeyFrom = double.NegativeInfinity;
}
else
{
qp.PartitioningKeyFrom = Partitions[i - 1].PartitioningKeyTo;
}
AppendPartition(qp);
}
Partitions[Partitions.Count - 1].PartitioningKeyTo = double.PositiveInfinity;
}