For all entries in sap abap

The for all entries creates a where clause, where all the entries in the driver table are combined with OR. If the number of
entries in the driver table is larger than rsdb/max_blocking_factor, several similar SQL statements are executed to limit the
length of the WHERE clause.

The plus

• Large amount of data
• Mixing processing and reading of data
• Fast internal reprocessing of data
• Fast

The Minus

• Difficult to program/understand
• Memory could be critical (use FREE or PACKAGE size)

Some steps that might make FOR ALL ENTRIES more efficient:

• Removing duplicates from the the driver table
• Sorting the driver table

If possible, convert the data in the driver table to ranges so a BETWEEN statement is used instead of and OR statement:
FOR ALL ENTRIES IN i_tab
WHERE mykey >= i_tab-low and
mykey <= i_tab-high.

Nested selects

The plus:

• Small amount of data
• Mixing processing and reading of data
• Easy to code - and understand

The minus:

• Large amount of data
• when mixed processing isn’t needed
• Performance killer no. 1