需要优化选择查询

Question

I have a query that does a select with joins from multiple tables that contains in total about 90 million rows. I only need data from the last 30 days. The problem is that when I run the select query the sql server throws a timeout while the query is running and new records are not created during this time frame. This query takes about 5 seconds to complete.

I would like to optimise this query so that it wont go through the entire tables looking at the datetime and would only search from the latest entries.

Right now it seems that I would need to index datetime column. Please advise if I need to create indexes or if there is another way to optimise this query.

SELECT [table1].Column1 AS InvoiceNo,
       'ND' AS VATRegistrationNumber,
       'ND' AS RegistrationNumber,
       Column2 AS Country,
       [table2].Column3 + ' ' + [table2].Column4 AS Name,
       CAST([table1].Column5 AS date) AS InvoiceDate,
       'SF' AS InvoiceType,
       '' AS SpecialTaxation,
       '' AS VATPointDate,
       ROUND([table1Line].Column6, 2) AS TaxableValue,
       CASE
            WHEN [table1Line].Column7 = 9 THEN 'PVM2'
            WHEN [table1Line].Column7 = 21 THEN 'PVM1'
            WHEN [table1Line].Column7 = 0 THEN 'PVM14'
       END AS TaxCode,
       CAST([table1Line].Column7 AS int) AS TaxPercentage,
       table1Line.Column8 - ROUND([table1Line].Column6, 2) AS Amount,
       '' AS VATPointDate2,
       [table1].Column1 AS InvoiceNo,
       '' AS ReferenceNo,
       '' AS ReferenceDate,
       [table1].CustomerPersonID AS CustomerID
FROM [table1]
     INNER JOIN [table2] ON [table1].CustomerPersonID = [table2].ID
     INNER JOIN [table3] ON [table2].Column9 = [table3].ID
     INNER JOIN [table1Line] ON [table1].ID = [table1Line].table1ID
     INNER JOIN [table4] ON table1Line.TaxID = Tax.ID
     INNER JOIN [table5] ON [table1].CompanyID = Company.ID
     INNER JOIN table6 ON [table1].SalesChannelID = table6.ID
WHERE Column5 LIKE '%date%'
  AND table6.id = 5
   OR table6.id = 2
  AND Column5 LIKE '%date%'
ORDER BY Column5 DESC;

Answer 1

First things first, each database runs a little differently because the optimizer has been running and figuring out how the unique circumstances can be improved and continuously tries to make common things run better.

There's also versioning differences that also play a part is the performance of the server.

Besides that stuff, Here's a few things to do to optimize this query. When working with Joins, Your Joined table comes first then compare against the already specified table.

For example t2 checks against t1:

select t1.name, t2.car
from customers as t1
left join purchases as t2
on t2.customerid = t1.customerid

The next thing I see is the Like condition in the Where part of the code.
The stored date that it's finding is stored as text in your example.
I would recommend processing the date as a datetime instead of a string type of datatype.

I would include that in the code below, but I'm not sure what the format looks like for your string of text.

%date% is the same thing as saying "Contains date".
This takes the date string, and tries to see if it matches in every position of characters from left to right.

So if your date text is 20200130, it will check to see if it matches 2date0200130, then tries 20date200130, then tries 202date00130, etc.
It will significantly increase the time it takes to process.

I also see that the date is being searched accidently two times instead of one.

I would recommend doing:

WHERE LTRIM(RTRIM(Column5)) LIKE 'date'

As for the Inner Joins, I would not use them. Use the Left join, and then in the Where, I would make sure it had no Null values for that joined data.
This makes the Left Join work the same as the Inner Join and runs more optimally when you are running the query.

For Instance, the first Join would look like this:

FROM [table1]
LEFT JOIN [table2] ON [table2].ID = [table1].CustomerPersonID
WHERE table2.id IS NOT NULL

I see an error in the code in the Where statement:

AND table6.id = 5
OR tables6.id = 2

This should be:

AND (tables6.id = 5 OR tables6.id = 2)

So here should be an optimized version of your code:

SELECT [table1].Column1 AS InvoiceNo,
'ND' AS VATRegistrationNumber,
'ND' AS RegistrationNumber,
Column2 AS Country,
[table2].Column3 + ' ' + [table2].Column4 AS Name,
CAST([table1].Column5 AS date) AS InvoiceDate,
'SF' AS InvoiceType,
'' AS SpecialTaxation,
'' AS VATPointDate,
ROUND([table1Line].Column6, 2) AS TaxableValue,
(CASE WHEN [table1Line].Column7 = 9 THEN 'PVM2'
      WHEN [table1Line].Column7 = 21 THEN 'PVM1'
      WHEN [table1Line].Column7 = 0 THEN 'PVM14'
      ELSE '' END ) AS TaxCode,
CAST([table1Line].Column7 AS int) AS TaxPercentage,
table1Line.Column8 - ROUND([table1Line].Column6, 2) AS Amount,
'' AS VATPointDate2,
[table1].Column1 AS InvoiceNo,
'' AS ReferenceNo,
'' AS ReferenceDate,
[table1].CustomerPersonID AS CustomerID
FROM [table1]
LEFT JOIN [table2] ON [table2].ID = [table1].CustomerPersonID
LEFT JOIN [table3] ON [table3].ID = [table2].Column9
LEFT JOIN [table1Line] ON [table1Line].table1ID = [table1].ID
LEFT JOIN [table4] ON [table4].ID = table1Line.TaxID
LEFT JOIN [table5] ON [table5].ID = [table1].CompanyID
LEFT JOIN [table6] ON table6.ID = [table1].SalesChannelID
WHERE table2.ID IS NOT null
AND table3.ID IS NOT null
AND table1Line.ID IS NOT null
AND table4.ID IS NOT null
AND table5.ID IS NOT null
AND table6.ID IS NOT null
AND LTRIM(RTRIM(Column5)) LIKE 'date'
AND (table6.id = 5 OR table6.id = 2)
ORDER BY Column5 DESC;