How to enhance performance of tables combination? - powerbi

Question

I have a list of tables (in actual data) with different columns for which, after to combine, I get a table of 15 columns. In actual data, the list of tables is get from several previous steps and each step takes less than a second, but only Table.Combine() takes almost 2 minutes with an input of about 1200 rows. In order to show the example, I show below an output of 4 columns only,
Is there a faster alternative way to get the same output given by Table.Combine()? Thanks for any help.
This is the code of the query I has so far.
let
Tables = {
Table.FromRecords({[Name = "Bob", Phone = "123-4567"],
[Name = "",Phone = ""]
}),
Table.FromRecords({[Fax = "987-6543", Phone = "838-7171"],
[Fax = "", Phone = "233-687"],
[Fax = "", Phone = "544-778"]
}),
Table.FromRecords({[Cell = "543-7890"],
[Cell = ""],
[Cell = ""]
})
},
CombinedTable = Table.Combine(Tables)
in
CombinedTable
The current output is:
UPDATE
This is the entire query, with Table.Buffer() added in step group5
let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("jVNdb4JAEPwvPFty3KHUR1C4Sg+0x5lqqSF+tGlqH5q0mv787hkal41FEsLNLjczu5NQlk6kpqP7yixnceU5Pad+Vr3SCQF4qI4A9FE9AiBQXcyj6qTWlBkDYKiOSd1C8wkNTyPpdK174DntHpzscUucB8R5iOqE6rU6B1ecOXEeEueOUXmE5nejBS1uCZHt6C5JnCge3mReiiMLJ/mNELidARgZreMCNTWAsQozPMgC0N2DFbHK8unUTTOr9XxgTGzzuVIn9AKtRZrDe7M5uod3xrj7uf8I2MD9Or7u1t9rxA2VmsJRGIPui//vX/CK8rOX7zHLFXBgbntM9L+T01koSUaRnvQNiciEanw1Ir37gSLZ7mx/Uw/qcbFvDKjjFD7Bijq1Eywf64uC87egWwzS/xP3hmfG6hc=", BinaryEncoding.Base64), Compression.Deflate)),
let
_t = ((type nullable text) meta [Serialized.Text = true])
in
type table [COL1 = _t, COL2 = _t, COL3 = _t, COL4 = _t]
),
fx = each not List.IsEmpty(List.RemoveItems(_,{"",null})),
group0 = Table.Group(Source, "COL2", {"n", each _}, 0, (x, y) => Byte.From(y = "" or y = null)),
group1 = Table.TransformColumns(
group0,
{
"n",
each
let
a = Table.Skip(_),
b = Table.FirstN(a, each [COL3] = "" or [COL3] = null),
c = Table.Skip(a, Table.RowCount(b))
in
[a = a, b = b, c = c]
}
),
group2 = Table.TransformColumns(
group1,
{"n", each Table.ToColumns(Table.Transpose([b])) & Table.ToColumns([c])}
),
group3 = Table.TransformColumns(group2, {"n", each List.Select(_, fx)}),
group4 = Table.TransformColumns(group3, {"n", each Table.FromColumns(_)}),
group5 = Table.Buffer( Table.TransformColumns(group4, {"n", each Table.PromoteHeaders(_)}) ) ,
combine = Table.Combine(group5[n]),
Custom1 = Table.SelectRows(combine, each fx(Record.ToList(_)))
in
Custom1
The purpose of this query is to tabulate data that appears in repeated blocks and subblock in the way I show below.
This is the output given by the query.

Answer 1

No, but try wrapping the initial table definitions as you go along in Table.Buffer()
let
a= Table.Buffer(Table.FromRecords({[Name = "Bob", Phone = "123-4567"],[Name = "",Phone = ""]})),
b= Table.Buffer(Table.FromRecords({[Fax = "987-6543", Phone = "838-7171"], [Fax = "", Phone = "233-687"],[Fax = "", Phone = "544-778"]})),
c= Table.Buffer(Table.FromRecords({[Cell = "543-7890"],[Cell = ""],[Cell = ""]})),
CombinedTable = Table.Combine({a,b,c})
in CombinedTable