Performance implications of using "SET INDICATORS"

[hbehrens]

I have to update a db table (HANA column store) from a very large itab (millions of rows), but only want to update very few columns - always the same columns, but different values for every row.

I figured I'd use the "INDICATORS" keyword, but the performance is abysmal when compared to the regular version.

TYPES type_db_ind TYPE dbtab WITH INDICATORS update_indicators.
TYPES type_dbtab
  TYPE SORTED TABLE OF type_db_ind 
        WITH UNIQUE KEY ....
DATA large_itab TYPE type_dbtab. "some non-key fields will be initial!
...
UPDATE dbtab
FROM TABLE @large_itab
INDICATORS SET STRUCTURE update_indicators.

Shouldn't it be *faster* considering it's only changing 4 columns of a 60 col table? It seems as if it is doing single updates, one row at a time.

TYPES type_dbtab TYPE SORTED TABLE OF dbtab
  WITH UNIQUE KEY ....

DATA large_itab TYPE type_dbtab. "*all* fields have to be read from dbtab first
...
UPDATE dbtab
FROM TABLE @large_itab.

Is there any way (maybe a parameter) to speed this up or do I still have to read the db table in whole just to update a few columns?

[horst_keller]

In your code, it is not shown how the indicator structure is filled.

You say "some non-key fields will be initial!

Where? Can you show, how you fill the indicator structure with value hexadecimal 1 for the fields to be updated?

[hbehrens]

Thanks for your reply! I'll try to elaborate:

"some non-key fields will be initial"

A) Some non-key fields I know will never change ("created by" won't change in an update)

===> Indicator field is always "00", field in abap struct is initial.

B) Some fields will always be updated (changed_by, cond_value...)

===> Indicator field is always "01", field in abap struct is never initial.

"How is the indicator structure filled?"

This is being done in a loop over all rows of the itab which will be used during the UPDATE. Because I know exactly what fields will be changed during an update I can set them like this:

CONSTANTS gc_update_set TYPE x VALUE '01'.
...
    cs_update_price-update_indicators = VALUE #(
      cond_value = gc_update_set
      cond_curr = gc_update_set
      base_quan = gc_update_set
      base_unit = gc_update_set
      delete_flag = gc_update_set
      changed_at = gc_update_set
      changed_by = gc_update_set
      changed_in = gc_update_set ).

This is the actual dbtab, fields that will have their indicator = '01' are highlighted in green, all other non-key fields will be initial in the itab during the UPDATE: