Re[2]: Suggestion for docs, section "4.2.3 Subscripts": bounds and base

On Thu, 2025-04-03 at 18:22 +0000, PG Doc comments form wrote:

Page: https://www.postgresql.org/docs/17/sql-expressions.html

Description:

 

I skimmed over section 4.2 while waiting for a meeting to start and found no

mention of the following two questions that immediately pop up in my mind

when subscripts are mentionned:

 

Are subscripts 0-based or 1-based?

 

This question is answered in the documentation of the array data types:

https://www.postgresql.org/docs/current/arrays.html

 

The array subscript numbers are written within square brackets. By default

PostgreSQL uses a one-based numbering convention for arrays, that is, an

array of n elements starts with array[1] and ends with array[n].

 

Are slice boundaries inclusive or exclusive?

 

That becomes clear on the same page:

 

We can also access arbitrary rectangular slices of an array, or subarrays.

An array slice is denoted by writing lower-bound:upper-bound for one or

more array dimensions. For example, this query retrieves the first item

on Bill's schedule for the first two days of the week:

 

SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = 'Bill';

 

schedule

------------------------

{{meeting},{training}}

(1 row)

 

Admittedly, there is no exact definition, but the example makes clear that

the boundaries are inclusive.

 

I don't think that we need to repeat that information.

 

Yours,

Laurenz Albe