Help with Analytics Query - Optimize and Index

Analytics
2

I am not analytic expert. Checkout Analytics Index with IN - #2 by dmitry.lychagin

Can you rewrite as follows without repeatedly scan of the data?

WITH available_report_docs AS (
        SELECT td.DocNum, td.`$MdfdTmstmp` AS timestamp
        FROM tranData td
        WHERE td.`$MdfdTmstmp` BETWEEN "{report_date}" and "{report_end_date}"
        AND td.RteId = "{report_route}"
        AND td.`$Type`="DailyReport"
        UNION ALL
        SELECT mch.DocNum, td.`$MdfdTmstmp` AS timestamp
        FROM tranData td
        UNNEST td.ActvCustOrdr AS mch
        WHERE td.`$MdfdTmstmp` BETWEEN "{report_date}" and "{report_end_date}"
        AND td.RteId = "{report_route}"
        AND td.`$Type`="DailyReport"
    ),
    available_cb_docs AS ( SELECT DISTINCT RAW c.DocNum
                           FROM available_report_docs AS c
                           WHERE c.timestamp BETWEEN "{previous_date}" and "{report_end_date}"),
    available_daily_report_docs AS ( SELECT DISTINCT RAW c.DocNum FROM available_report_docs AS c)
    SELECT ARRAY_SYMDIFF(available_daily_report_docs, available_cb_docs) AS cust_order_missing_docs;

adjust based on which date is earliest {previous_date} or “{report_date}”
If Analytic supports EXCEPT see if works for you

...............
SELECT RAW c1.DocNum FROM available_report_docs AS c1
 EXCEPT
 SELECT RAW c.DocNum FROM available_report_docs AS c WHERE c.timestamp BETWEEN "{previous_date}" and "{report_end_date}"