Power Query Doesn't Load my 6GB / 200K Rows into Excel's View, Even With Data Loading in Power Query

bubbledep Let's try with:

let
Source = Table.Combine({PRICES_A, PRICES_B, PRICES_C, PRICES_D, PRICES_E, PRICES_F, PRICES_G, PRICES_H, PRICES_I, PRICES_J, PRICES_K, PRICES_L, PRICES_M, PRICES_N, PRICES_O, PRICES_P}),

// Sort by DATE in ascending order
SortedTable = Table.Sort(Source, {{"DATE", Order.Ascending}}),

// Group by all condition columns to ensure we find previous prices within the same group
GroupedTable = Table.Group(SortedTable, {"columnCONDITION1", "columnCONDITION2", "columnCONDITION3"},
{{"All Data", each _, type table [DATE=nullable date, PRICE=nullable number]}}),

// Add a column to find previous DATE and PRICE
AddPreviousPrice = Table.AddColumn(GroupedTable, "All Data", each
let
Grouped = [All Data],
Sorted = Table.Sort(Grouped, {{"DATE", Order.Ascending}}),
AddPrevious = Table.AddColumn(Sorted, "Prev Date", each try Sorted[DATE]{List.PositionOf(Sorted[DATE], [DATE])-1} otherwise null),
AddPrevPrice = Table.AddColumn(AddPrevious, "Prev Price", each try Sorted[PRICE]{List.PositionOf(Sorted[DATE], [DATE])-1} otherwise null)
in
AddPrevPrice, type table [DATE=nullable date, PRICE=nullable number, Prev Date=nullable date, Prev Price=nullable number]
),

// Expand back the grouped data
ExpandedTable = Table.ExpandTableColumn(AddPreviousPrice, "All Data", {"DATE", "PRICE", "Prev Date", "Prev Price"}),

// Rename columns for clarity
RenamedColumns = Table.RenameColumns(ExpandedTable, {{"Prev Date", "DATE D-1"}, {"Prev Price", "PRICE D-1"}})

in
RenamedColumns

BBF