Incredibly slow performance with this query - sql

Question

I am getting incredibly slow performance when executing this query,
i cannot see anything obvious,can any one suggest me the best way to get through it
CREATE TABLE #tmp_NominalPurchase (
NomCode varchar(16),
NomDesc varchar(61),
GoodsSold money
)
declare #Pos Int
select #Pos = 1
while #Pos <= (select max(dbo.fn_DCount(NValues,'~')) from pledger)
begin
INSERT INTO #tmp_NominalPurchase (NomCode, NomDesc, GoodsSold) (
select
a.keyCode NomCode,
a.descr NomDesc,
sum(convert(money, dbo.fn_Field(pl.NValues,'~', #Pos) )) GoodsSold
from pledger pl
inner join accts a
On dbo.fn_Field(pl.NCodes,'~', #Pos) = a.keycode
and (acctType='N' and pb='P' and category='cs')
where convert(datetime, pl.batch) >='2014-01-01'
and convert(datetime, pl.batch) <'2014-06-25'
group by a.keyCode, a.descr)
select #Pos = #Pos + 1
end
select o.* FROM
(
select t.NomCode,
t.NomDesc,
0 GoodsCost,
0 GoodsDisc,
sum(t.GoodsSold) GoodsSold,
'24/06/2014 05:01:14 PM' as LocalDateAndTime
from #tmp_NominalPurchase t
group by
t.NomCode,
t.NomDesc
) o
Order By o.NomCode Asc
DROP TABLE #tmp_NominalPurchase

Answer 1

One obvious thing I see is you are converting pl.batch to a string before you do the comparison in the where clause. That would defeat any indices that might prevent a table scan.
You are also doing a join on a user defined function fn_field. Not knowing the purpose of that function, I'm wondering if that is creating an issue. When I see things like that, I suspect it's there because the data schema isn't well thought out.

Answer 2

No rewritten query and performance has increased majorly, this has reduced the query runtime from 12 seconds to < 1 second
added a function to get the count
SQL rewritten to use the count
The Improved SQL
SELECT dbo.fn_Field(pl.NValues,'~',1) AS [nVals1], dbo.fn_Field(pl.Ncodes,'~',1) as [nCodes1], dbo.fn_Field(pl.NValues,'~',2) as [nVals2], dbo.fn_Field(pl.Ncodes,'~',2) as [nCodes2],
'x' AS x INTO #tmp_NominalPurchase
FROM pledger pl
WHERE convert(datetime, pl.batch) >='2014-06-01'
AND convert(datetime, pl.batch) <'2014-06-28'
SELECT a.keycode AS NomCode,
a.descr AS NomDesc,
max(0) AS goodsCost,
max(0) AS GoodsDisc,
sum(CAST (NValue AS money)) AS GoodsSold ,
'06/27/2014 11:44:47 AM' AS LocalDateAndTime
FROM
(SELECT [nVals1] AS NValue,[nCodes1] AS NCode
FROM dbo.#tmp_NominalPurchase tnp
UNION ALL SELECT [nVals2]AS NValue,[nCodes2] AS NCode
FROM dbo.#tmp_NominalPurchase tnp) x
INNER JOIN dbo.Accts a ON x.Ncode = a.keycode
AND acctType='N'
AND category='cs'
AND pb='P'
GROUP BY a.keycode,
a.descr
ORDER BY NomCode
DROP TABLE #tmp_NominalPurchase
Function to get count
Public Function getNCodeCount(ByVal sWhere) As Integer '00528591
Dim Ds As DataSet
Dim sqlSb As StringBuilder = New StringBuilder
Dim nCodesCount As Integer = 0
sqlSb.Append("SELECT isnull(max(dbo.fn_DCount(NValues,'~')),0) FROM PLEDGER PL with (nolock)" & sWhere)
Ds = SqlConnect.SqlNet.OpenSQLdataset(sqlSb.ToString)
If Ds Is Nothing Then GoTo report_failed
If Ds.Tables.Count < 1 Then
GoTo report_failed
End If
With Ds.Tables(0)
For Each r In .Rows
nCodesCount = r(0)
Next
End With
Return nCodesCount
Exit Function
report_failed:
Return 0
'00528591 END
End Function
Function to build the SQL string and output the report
Public Function LedgerNominalListingReportPurchase(ByVal DateFrom As String, ByVal DateTo As String, ByVal SortType As String, Optional ByVal DetailReport As Boolean = False, Optional ByVal NominalCode As String = "") As DataView 'L754303 (163.47)
Dim sql As String = ""
Dim gs As New GeneralSQL
Dim aWhere As New ArrayList
Dim sWhere As String = ""
If IsDate(DateFrom) Then aWhere.Add("convert(datetime, pl.batch) >=" & gs.SqlDate(CDate(DateFrom)))
If IsDate(DateTo) Then aWhere.Add("convert(datetime, pl.batch) <" & gs.SqlDate(CDate(DateTo).AddDays(1)))
For Each s As String In aWhere
If sWhere = "" Then
sWhere &= " where "
Else
sWhere &= " and "
End If
sWhere &= s
Next
If Not DetailReport Then 'L754303 (163.47)
'NEW SQL (FASTER) 00528591
sql &= "SELECT max(dbo.fn_DCount(NValues,'~')) FROM PLEDGER"
Dim nCodeCount As Integer = (getNCodeCount(sWhere))
If nCodeCount = Nothing Or 0 Then
sql = "CREATE TABLE #tmp_NominalPurchase (NomCode varchar(16), NomDesc varchar(61), GoodsCost money, GoodsDisc money, GoodsSold money) SELECT * FROM #tmp_NominalPurchase DROP TABLE #tmp_NominalPurchase"
Else
Dim qCount As Integer = 1
sql = "SELECT "
While qCount <= nCodeCount
sql &= "dbo.fn_Field(pl.NValues,'~'," + qCount.ToString
sql &= ") "
sql &= " as [nVals" + qCount.ToString
sql &= "], "
sql &= "dbo.fn_Field(pl.Ncodes,'~'," + qCount.ToString
sql &= ") "
sql &= " as [nCodes" + qCount.ToString
sql &= "], "
qCount += 1
End While
sql &= " 'x' as x "
sql &= "INTO #tmp_NominalPurchase FROM pledger pl " & sWhere
sql &= "SELECT a.keycode as NomCode, a.descr as NomDesc,max(0) AS goodsCost,max(0) AS GoodsDisc, sum(cast (NValue AS money) ) AS GoodsSold "
sql &= String.Format(", '{0}' as LocalDateAndTime", Format(General.UserNow, vars.Ses.FmtDate & " " & "hh:mm:ss tt")) 'V759658 (163.31) - format the date column based on the CountryMode setting
sql &= " FROM ("
sql &= "SELECT [nVals1] AS NValue,[nCodes1] AS NCode FROM dbo.#tmp_NominalPurchase tnp "
qCount = 2
While qCount <= nCodeCount
sql &= " UNION all "
sql &= "SELECT [nVals" + qCount.ToString
sql &= "]AS NValue,[nCodes" + qCount.ToString
sql &= "] AS NCode FROM dbo.#tmp_NominalPurchase tnp"
qCount += 1
End While
sql &= ") x inner join dbo.Accts a on x.Ncode = a.keycode and acctType='N' AND category='cs' AND pb='P' group by a.keycode,a.descr "
sql &= "ORDER BY " & SortType
sql &= " DROP TABLE #tmp_NominalPurchase"
End If
End If
Return SqlConnect.SqlNet.OpenSQLdataset(sql).Tables(0).DefaultView '00529265
End Function