OracleDataAdapter.Fill Is Slow

Question

All,
Can anyone help me understand why the call to oda.Fill in this function is so slow, about 8 to 10 seconds? If I execute the same SQL in Toad, it executes reliably about 500 milliseconds. I'm using Oracle.DataAccess v4.
Public Shared Function Get24() As Data.DataTable
Dim EndDT As Date = Now
Dim StartDT As Date = EndDT.AddHours(-24)
Dim sb As New System.Text.StringBuilder
sb.Append("SELECT TO_TIMESTAMP(TO_CHAR(completed_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM') || TO_TIMESTAMP(TO_CHAR(rejected_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM') As DTS," & Space)
sb.Append("DECODE(mes_srno_status,'03',0,'04',1) AS VALS," & Space)
sb.Append("MES_ASSY_JOB_INFO.*" & Space)
sb.Append("FROM MES_ASSY_JOB_INFO" & Space)
sb.Append("WHERE" & Space)
sb.Append("mes_srno_status IN ('03','04')" & Space)
sb.Append("AND TO_TIMESTAMP(TO_CHAR(completed_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM')" & Space)
sb.Append("|| TO_TIMESTAMP(TO_CHAR(rejected_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM')" & Space)
sb.Append("BETWEEN :StartDate AND :EndDate" & Space)
Using oc As New OracleCommand(sb.ToString, DAL.ODP.GetConnectionPMESDB)
Dim p1 As New OracleParameter("StartDate", OracleDbType.TimeStamp, StartDT, ParameterDirection.Input)
Dim p2 As New OracleParameter("EndDate", OracleDbType.TimeStamp, EndDT, ParameterDirection.Input)
oc.Parameters.Add(p1)
oc.Parameters.Add(p2)
Using oda As New Oracle.DataAccess.Client.OracleDataAdapter(oc)
Dim tempDT As New Data.DataTable
oda.Fill(tempDT)
Dim dt As New Data.DataTable
Dim dc As DataColumnCollection = tempDT.Columns
For Each c As Data.DataColumn In dc
dt.Columns.Add(c.ColumnName, c.DataType)
Next
dt.Columns(0).DataType = GetType(Date)
For Each dr As Data.DataRow In tempDT.Rows
Dim dr1 As Data.DataRow = dt.Rows.Add
Dim d As Date = Oracle.DataAccess.Types.OracleTimeStamp.Parse(dr(0))
dr1(0) = d
For i As Integer = 1 To dr.Table.Columns.Count - 1
dr1(i) = dr(i)
Next
Next
Return dt
End Using
End Using
End Function
The string builder produces the following SQL:
SELECT TO_TIMESTAMP(TO_CHAR(completed_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM')
|| TO_TIMESTAMP(TO_CHAR(rejected_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM') AS DTS,
DECODE(mes_srno_status,'03',0,'04',1) AS VALS,
MES_ASSY_JOB_INFO.*
FROM MES_ASSY_JOB_INFO
WHERE mes_srno_status IN ('03','04')
AND TO_TIMESTAMP(TO_CHAR(completed_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM')
|| TO_TIMESTAMP(TO_CHAR(rejected_time,'DD/MM/YY HH:MI:SS PM'),'DD/MM/YY HH:MI:SS PM') BETWEEN :StartDate AND :EndDate

Answer 1

Is it the Fill method that is slow or something else, such as creating the connection pool? It would be easier to diagnose what the potential problem could be if we know which API calls are operating inordinately slowly.