Re: Performance hit with trigger program

You don’t say what AG you are using but that would also potentially have
an impact. It is the constant close/open of the file that is killing you
when setting LR on.

No need to set on LR each time but without it you need to decide how you
are going to close the file.


Jon Paris

www.partner400.com
www.SystemiDeveloper.com

On Apr 7, 2016, at 11:25 AM, Dan <dan27649@xxxxxxxxx> wrote:

I'm testing the trigger app I developed with help from some of you here
these past few days.

I ran an iteration of performance tests. A simple program that reads (by
key) the OWNER table, updates a field, and updates the OWNER record,

inside

a FOR X = 1 TO 100000 loop. I ran this program 20 times; odd-numbered

runs

without a trigger, even-numbered runs with a trigger. The difference was
significant. Without a trigger, the 10 runs averaged 3.4 seconds. With

a

trigger, the 10 runs averaged 198.9 seconds. The 100,000 records is
representative of the batch job volumes they have here. The OWNER table

is

updated in interactive programs as well.

Reviewing several examples of trigger programs online, I noticed that all
of them turned on the LR indicator. For testing, I no-op'd the EVAL
*INLR=*ON so the program would compile, but never have LR turned on.
Duplicating the previous test cycle, without a trigger, the 10 runs
averaged 3.6 seconds. With a trigger, the 10 runs averaged 11.8 seconds.
Yeah, about 16 times faster than when turning LR on.

As you can tell by the program source I've included below, this is a

simple

app that basically acts like a journal, so there's no need for
initialization each time it's called. I was concerned that each of the
100,000 calls would put 100,000 instances of the trigger program in the
job's call stack, but that was not the case. The output file in the
trigger program remained open after my test run completed. I'm not sure
whether this a concern, because there are about 200 interactive users who
will be doing something throughout their day that updates the OWNER

table.

CAN ANYONE ADVISE WHETHER THERE ARE ANY PROBLEMS WITH THIS APPROACH?

Oh, and for those who will inevitably ask, I was told that we cannot turn
on journaling. This is my second week here, and I don't have enough

clout

to delve into the why.

fTRG001H o e disk
d pi ExtPgm( 'TRG001R' )
d eTrgBuffer LikeDS( TrgBuffer )
d eTrgBufferLen Like( TrgBufferLen )
/copy TRGBUFCOPY
d TriggerPtr s *
d TriggerRecord e ds ExtName( OWNER )
d Based( TriggerPtr )
d Prefix( T_ )
d OutputRecord e ds ExtName( OWNER )

Select;
When eTrgBuffer.tbEvent = '1'; // Insert
TriggerPtr = %addr( eTrgBuffer ) + eTrgBuffer.tbNewOffset ;
TrgType = 'I';
When eTrgBuffer.tbEvent = '2'; // Delete
TriggerPtr = %addr( eTrgBuffer ) + eTrgBuffer.tbOldOffset ;
TrgType = 'D';
When eTrgBuffer.tbEvent = '3'; // Update
TriggerPtr = %addr( eTrgBuffer ) + eTrgBuffer.tbNewOffset ;
TrgType = 'C';
Endsl;

TrgTmStamp = %timestamp;

OutputRecord = TriggerRecord;
Write TRG001Hr;

If *inLR <> *inLR; // Test for performance by not turning LR on
*inLR = *on;
Endif;
Return;

copy member TRGBUFCOPY:
d TrgBuffer ds
d tbFileName 10
d tbLibraryName 10
d tbMemberName 10
d tbEvent 1
d tbTime 1
d tbCommitLock 1
d tbFill01 3
d tbCCSID 10i 0
d tbRRN 10i 0
d tbFill02 10i 0
d tbOldOffset 10i 0
d tbOldLength 10i 0
d tbOldNullOff 10i 0
d tbOldNullLen 10i 0
d tbNewOffset 10i 0
d tbNewLength 10i 0
d tbNewNullOff 10i 0
d tbNewNullLen 10i 0
d tbBufChar 1 32767
d tbBufArry 1 Overlay( tbBufChar )
d Dim( %size( tbBufChar ))

d TrgBufferLen s 10i 0
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