feat: support specifying columns to include in the "Attach table" statement #17442
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Summary
Allow optionally specifying which columns to include in the 'Attach table' statement.
e.g.
To create a table named
test_tbl
that attaches to the path 's3://databend-toronto/1/556/' and includes only the columnscol1
andcol2
, you can use the following SQL statement:Suppose the table
base
is being attached:base
table will faile.g.
attach table attach_tbl (c2, c_not_exist) ....
will failDropping non-included columns from
base
does not mattere.g.
Renaming included columns of
base
does not mattere.g.
Column that have been dropped from
base
table will be inaccessiblee.g.
select *
should still work, as long as there is at least one column left:if all the attached columns have been dropped from the
base
table,attach_tbl
can no longer be scanned:fixes: Feature: Support specifying columns to include in the "Attach table" statement. #17439
Tests
Type of change
This change is![Reviewable](https://camo.githubusercontent.com/1541c4039185914e83657d3683ec25920c672c6c5c7ab4240ee7bff601adec0b/68747470733a2f2f72657669657761626c652e696f2f7265766965775f627574746f6e2e737667)