Performance improvement hints: date, time, timestamps

[harry_dietz]

To glue date and time to a timestamp or to split a timestamp into date and time it is possible to do this in a various ways. (By "glue" I mean to create a timestamp out of a date and a time so the time zone stays the same and by "split" I mean to split up a timestamp so a date and a time is created with the same time zone; So this blog concentrates on no time zones...if you need time zone conversion, you have to use CONVERT) I show which one takes which time.

From date and time to a timestamp

via convert date time

data:  lv_timestamp type timestamp.convert date sy-datum time sy-uzeit into time stamp lv_timestamp time zone 'UTC   '.

via concatenate

data:   lv_char14 type char14,   lv_timestamp type timestamp.concatenate sy-datum sy-uzeit into lv_char14.lv_timstamp = lv_char14.

via char modification (1)

data:   lv_char14 type char14,   lv_timestamp type timestamp.lv_char14(8) = sy-datum.lv_char14+8(6) = sy-uzeit.lv_timstamp = lv_char14.

via char modification (2)

data:   lv_char14 type char14,   lv_timestamp type timestamp.lv_char14 = sy-datum.lv_char14+8 = sy-uzeit.lv_timstamp = lv_char14.

via structure

types:  begin of datetimestr,    datum type sydatum,    uzeit type syuzeit,  end of datetimestr.data:   ls_datetimestr type datetimestr,   lv_timestamp type timestamp.ls_datetimestr-datum = sy-datum.ls_datetimestr-uzeit = sy-uzeit.lv_timestamp = ls_datetimestr.

Comparison of the different types

And now for the comparison of the different types of date and time to timestamp conversions I measured these times:

conversion type	time consumed (no real times)
convert date time	21227
concatenate	2957
char modification (1)	2599
char modification (2)	2727
structure	2594

So this means that we should go for the "char modification (1)" or the "structure" conversion. But what this also means is, that the CONVERT DATE TIME INTO TIME STAMP TIME ZONE is a very very bad idea. Never use CONVERT!
So either do something like this
lv_char14(8) = sy-datum.
lv_char14+8(6) = sy-uzeit.
or something like this
types:
begin of datetimestr,
datum type sydatum,
uzeit type syuzeit,
end of datetimestr.
ls_datetimestr-datum = sy-datum.
ls_datetimestr-uzeit = sy-uzeit.

From timestamp to date and time

To do the split from timestamp to date and time, you can use nearly the same options as above: convert time stamp, char modifications and the structure thing.

via convert time stamp

data:  lv_timestamp type timestamp,  lv_datum type sydatum,  lv_uzeit type syuzeit.convert time stamp lv_timestamp time zone 'UTC   ' into date lv_datum time lv_uzeit.

via char modification

data:  lv_timestamp type timestamp,  lv_char14 type char14,  lv_datum type sydatum,  lv_uzeit type syuzeit.lv_char14 = lv_timestamp.lv_datum = lv_char14(8).lv_uzeit = lv_char14+8(6).

via structure

types:  begin of datetimestr,    datum type sydatum,    uzeit type syuzeit,  end of datetimestr.data:   ls_datetimestr type datetimestr,   lv_timestamp type timestamp,  lv_datum type sydatum,  lv_uzeit type syuzeit.ls_datetimestr = lv_timestamp.lv_datum = ls_datetimestr-datum.lv_uzeit = ls_datetimestr-uzeit.

Comparison of the different types

And now for the comparison of the different types of timestamp to date and time conversions I measured these times:

conversion type	time consumed (no real times)
convert date time	16250
char modification	10665
structure	10287

So this means that we should go for the "char modification (1)" or the "structure" conversion (the difference is not really big). And again never use CONVERT, it is not this bad in this example, but it is bad enough.
So either do something like this
lv_datum = lv_char14(8).
lv_uzeit = lv_char14+8(6).
or something like this
types:
begin of datetimestr,
datum type sydatum,
uzeit type syuzeit,
end of datetimestr.
ls_datetimestr = lv_timestamp.
lv_datum = lv_datetimestr-datum.
lv_uzeit = ls_datetimestr-uzeit.

Code for the measurement

And finally here is the code I used to measure the times (the naming in the coding is different):
TYPES:  BEGIN OF splitter,    datum TYPE sydatum,    uzeit TYPE syuzeit,  END OF splitter.DATA:  lv_start TYPE i,  lv_end TYPE i,  lv_c TYPE char14,  lv_cc TYPE char32,  ls_splitter TYPE splitter,  lv_timestamp1 TYPE timestamp,  lv_timestamp2 TYPE timestamp.DO 10 TIMES.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    CONCATENATE sy-datum sy-uzeit INTO lv_c.    lv_timestamp1 = lv_c.    WRITE lv_timestamp1 TO lv_cc.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'concat ', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    lv_c(8) = sy-datum.    lv_c+8(6) = sy-uzeit.    lv_timestamp1 = lv_c.    WRITE lv_timestamp1 TO lv_cc.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'copy 1 ', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    lv_c = sy-datum.    lv_c+8 = sy-uzeit.    lv_timestamp1 = lv_c.    WRITE lv_timestamp1 TO lv_cc.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'copy 2 ', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    ls_splitter-datum = sy-datum.    ls_splitter-uzeit = sy-uzeit.    lv_timestamp1 = lv_c.    WRITE lv_timestamp1 TO lv_cc.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'direct ', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    CONVERT      DATE sy-datum      TIME sy-uzeit      INTO      TIME STAMP lv_timestamp1      TIME ZONE 'UTC   '.    WRITE lv_timestamp1 TO lv_cc.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'convert', lv_end.ENDDO.WRITE: / sy-uline.DO 10 TIMES.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    GET TIME STAMP FIELD lv_timestamp1.    CONVERT      TIME STAMP lv_timestamp1      TIME ZONE 'UTC   '      INTO      DATE ls_splitter-datum      TIME ls_splitter-uzeit.    IF ls_splitter-datum > 0 AND ls_splitter-uzeit > 0.      ADD 1 TO ls_splitter-datum.      ADD 1 TO ls_splitter-uzeit.    ENDIF.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'convert ', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    GET TIME STAMP FIELD lv_timestamp1.    lv_c = lv_timestamp1.    ls_splitter-datum = lv_c(8).    ls_splitter-uzeit = lv_c+8(6).    IF ls_splitter-datum > 0 AND ls_splitter-uzeit > 0.      ADD 1 TO ls_splitter-datum.      ADD 1 TO ls_splitter-uzeit.    ENDIF.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'viachar1', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    GET TIME STAMP FIELD lv_timestamp1.    lv_c = lv_timestamp1.    ls_splitter-datum = lv_c.    ls_splitter-uzeit = lv_c+8.    IF ls_splitter-datum > 0 AND ls_splitter-uzeit > 0.      ADD 1 TO ls_splitter-datum.      ADD 1 TO ls_splitter-uzeit.    ENDIF.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'viachar2', lv_end.  GET RUN TIME FIELD lv_start.  DO 99999 TIMES.    GET TIME STAMP FIELD lv_timestamp1.    ls_splitter = lv_timestamp1.    IF ls_splitter-datum > 0 AND ls_splitter-uzeit > 0.      ADD 1 TO ls_splitter-datum.      ADD 1 TO ls_splitter-uzeit.    ENDIF.  ENDDO.  GET RUN TIME FIELD lv_end.  SUBTRACT lv_start FROM lv_end.  WRITE: / 'direct  ', lv_end.ENDDO. (use this to copy and paste in a test report)

...and something at the end on the CONVERT which has nothing to do with performance: please remember that the TIME ZONE is always related to the DATE and TIME parts. The TIME STAMP is always always always in UTC. There is no possibility that you can convert to or from a non-UTC timestamp with CONVERT!