Developed 'period'

Redundancy of syntax consist of two items:

superfluous service word 'valid'
~~valid period~~
period

also quotes around array is redundant

'[09/09/07 - now]'

[2009.01.01/05.00, now]

Besides this, syntax is not usable to extract invisible records by force, especially if time interval is specified not by constants, but by sub-query

it is much more usable to mark usual fields of data type 'datetime' by service word 'period'

create table figure (id   number,
                     time datetime array[2] period,
                     more varchar);

Earlier service words 'union, intersect, except' used for operations upon time ranges, and coincides by names with operations for records - what was simply criminal, because it created cognitive dissonance (different intities must not be designated by identical name).

it was required to change names for operations upon ranges

Use of usual arrays refers to operations upon arrays which names do not coincide with 'union, intersect, except', and thus reduce cognitive dissonance elegantly.

P.S.

Article clirifies p.223-224, 268-269 of pdf-document.

Dima Turin, dmitryturin@yandex.ru

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