Display a metric differently only on last day of the month.

Question

Have a Daily transaction fact where unit cost of product is stored at a day/part num /business unit level.
When we drag and drop date column and unit cost in the report like below we will have
Date      cost
Sep29     $10
sep30     $12
Oct1       $12
Oct2       $14
..........ans so on
The source sustem program runs on last day of the month around 8pm for setting up cost to reflect on 1st of every month
But the nighly OBI load ( Runs at 2am every day) when incrementally updating Sep30 data picks up $12 from the erp and populates in OBI.
But actually speaking, on Sep30 the cost was $10.
There is no way of running the ERP program to run afer OBI load. Hence we need an expression in the RPD (not answers) saying
when last day of the month (any month) the standard cost must be a previous day value.All other days the same value should be returned.
Is this possible without impacting report performance ?
So, when we drag and drop date and cost value the above report should change as
Date        Cost
sep29     $10
sep30     $10
Oct1       $12
Oct2       $14
Oct30     $12.5
Oct31     $12.5
Nov1      $13.5

Answer 1

You can achieve the above requirement for current month alone with below steps:
The solution requires to have a union report
First part of the report will have Date and Cost fields with a report level date filter, Date NOT IN (TIMESTAMPADD( SQL_TSI_DAY , -(1), TIMESTAMPADD( SQL_TSI_MONTH , 1, TIMESTAMPADD( SQL_TSI_DAY , DAYOFMONTH( CURRENT_DATE) * -(1) + 1, CURRENT_DATE))))
Second part of the report will have Date and Cost fields with a report level date filter Date IN (TIMESTAMPADD( SQL_TSI_DAY , -(1), TIMESTAMPADD( SQL_TSI_MONTH , 1, TIMESTAMPADD( SQL_TSI_DAY , DAYOFMONTH( CURRENT_DATE) * -(1) + 1, CURRENT_DATE))))In the second part of the report,
Change the column formula for Date to display only Current_Date
Change the column formula for Cost field with FILTER(Cost USING Date = Current_Date-1)
Pls mark if correct/helpful.