load(
/*This rule queryEntityRule1 should have only one column to fetch. This is used just to know the total count of DB data */
local!dataSubset: rule!queryEntityRule1(
              pagingInfo: a!pagingInfo(
                startIndex: 1,
                batchSize: - 1
              )
            ),
local!isModValue: if(mod(local!dataSubset.totalCount, cons!EXPORT_TO_EXCEL_BATCH_SIZE)>0, true, false), /*This batch size constant signifies how many rows the query will pull in one batch. you can configure this batch size based on your need. In my case I have set it up with 100 */
local!totalPageCount: int(local!dataSubset.totalCount/cons!EXPORT_TO_EXCEL_BATCH_SIZE),

with(
local!data: apply(rule!getDataForExcelExport, enumerate(local!totalPageCount)), /* This rule!getDataForExcelExport takes the batch number as input and calls the query per batch. I have the details of this rule separately. */
local!records: reduce(fn!append,{},local!data),
local!allData: if(local!isModValue, append(local!records, rule!getDataForExcelExport(local!totalPageCount)), local!records),
'type!{urn:appian:plugin:datasubsetdownload:types}ExportableDataSubset'(
    datasubset: todatasubset(local!allData, a!pagingInfo(startIndex: 1, batchSize: -1)),
    fieldNames: {<put field names as per your requirement>
	},
	fieldLabels: {<put field labels as per your requirement>
	},
    filename: "Excel file"
	)
)
)