Query Exceeded Available Resource

Hi rehansaeed2468 ,

Create the helper table first:

IndexTable =
DISTINCT (
SELECTCOLUMNS (
'Table B',
"RowIndex", 'Table B'[Row Index_TableB]))

Now create the DecayFactor column inside IndexTable (not Table B):

DecayFactor =
POWER ( 0.964783, IndexTable[RowIndex] )

This will work because of no circular dependency.

Final Measure =
VAR CurrentIndex =
SELECTEDVALUE ( 'Table B'[Row Index_TableB column] )

RETURN
IF (
ISBLANK ( CurrentIndex ),
BLANK (),
SUMX (
FILTER (
IndexTable,
IndexTable[RowIndex] <= CurrentIndex
),
IndexTable[DecayFactor]
* CALCULATE (
SUM ( 'Table B'[Product Cost] ),
'Table B'[Row Index_TableB] = IndexTable[RowIndex]
)))

Hope this helps.
Chaithra E