Row vs. tuple

In some places the documentation uses the term "tuple" to mean "row
version" (in the MVCC sense). This choice of terms is puzzling me; where
does it come from? In the literature available to me, the term "tuple" is
used as the mathematical equivalent of "row", meaning that
table/row/column parallels relation/tuple/attribute. This terminology is
also used in other parts of PostgreSQL. For example, libpq and derived
interfaces use "tuple" in function names to refer to rows. Should we not
make this usage consistent? I suggest we use "row version" when we mean
row version, which will also make things clearer to less experienced
users.

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Peter Eisentraut peter_e(at)gmx(dot)net