Introduction –
In this blog, you are going to see how performance can be improved using ‘WITH’ Clause in CDS Table function when you have multiple selects.
I will use below Problem Statement as an example and try same solution in 3 ways.
Problem Statement – Need to find the last person who changed CU Order Basic Start Date and when (i.e. ‘Changed By’ and ‘Changed on’ for Field AFKO-GSTRP).
Expected Result –
Solution –
First Read table CDHDR to get only latest change against AFKO-GSTRP
Then pass CDHDR-CHANGENR to CDPOS-CHANGER along with other keys in order to get User id and changed on.
Let’s begin –
OPTION 1: Using Multiple CDS Views
Step 1: Get the latest change on AFKO-GSTRP
Step 2: Get Change By (cdhdr-username) and changed on(cdhdr-udate / utime).
Result 1 - 1345ms for 100 records
OPTION 2: CDS Table Function
Here I have used 2 selects, 1st as highlighted to get latest ‘CHANGENR’ on AFKO-GSTRP and then get CDHDR-USERNAME and CDHDR-UDATE/UTIME.
Result 2: 883ms for 100 records
OPTION 3: CDS Table Function using ‘WITH’ Clause
Now here if you compare with Option 2, 1st select statement is now moved out using ‘WITH’ clause.
WITH Clause – stores the data in a buffer or temporary table (just like ABAP Internal Table) which boosts the performance.
Result 3: 316ms for 100 records
Code for Option 3:
1.CDS Table Function –
@EndUserText.label: 'CDHDR Logs'
define table function ZTF_CDHDR_LOGS
returns {
key client : abap.clnt;
key aufnr: aufnr;
username: cdusername;
FNAME: fieldname;
UpdateDate: abap.dats;
UpdateTime: abap.tims;
}
implemented by method zclget_cdhdr_logs=>zget_cdhdr_logs;
2. Class –
class ZCLGET_CDHDR_LOGS definition
public
final
create public .
public section.
interfaces if_amdp_marker_hdb.
class-methods zget_cdhdr_logs for table function ZTF_CDHDR_LOGS.
protected section.
private section.
ENDCLASS.
CLASS ZCLGET_CDHDR_LOGS IMPLEMENTATION.
method zget_cdhdr_logs
by database function for hdb
language sqlscript
options read-only
using cdhdr cdpos.
return
with pos as ( select max( changenr ) as chnr, FNAME from cdpos
where objectclas = 'ORDER' and
tabname = 'AFKO' and
fname = 'GSTRP'
group by objectid, FNAME)
select
hdr.mandant as client,
substring(hdr.objectid,6,12) as aufnr,
hdr.username,
pos.FNAME,
hdr.udate as UpdateDate,
hdr.utime as UpdateTime
from cdhdr as hdr , pos
where hdr.objectclas = 'ORDER' and
hdr.changenr = pos.chnr
;
endmethod.
ENDCLASS.
Conclusion:
Below are the performance results and this is just an example as I have not compared like to like records but still i can see improved response time on CDS Table Function using ‘WITH’ Clause.
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