References
Data Types
Interval

Reference: Interval Data Types

Intervals are a convenient way for arithmetic on date, time, and timestamp data. You can specify intervals in quantities of calendar units like day or month, with at most microseconds granularity. You can find a complete list of input units and options in the PostgreSQL docs.

Usage Example 

create table example (
    duration interval
);
insert into example
    values (interval '90' day), (interval '3 week'), (interval '1 month 1 day');
select * from example;
  duration
-------------
 90 days
 21 days
 1 mon 1 day
(3 rows)
By default, CedarDB prints intervals in the PostgreSQL style shown above. You can change the output format with the IntervalStyle setting, for example to the terse SQL standard format:
set IntervalStyle to 'sql_standard';
CedarDB supports the styles postgres, postgres_verbose, sql_standard, and iso_8601.

Why Intervals?

Date arithmetic with intervals automatically handle edge-cases like the irregular month lengths and leap years by using CedarDBs calendar for calculations.

select date '2024-05-31' + interval '1' month, date '2024-05-31' + interval '2' month;
      ?column?       |      ?column?       
---------------------+---------------------
 2024-06-30 00:00:00 | 2024-07-31 00:00:00
(1 row)
select date '2024-02-28' + interval '2' day;
      ?column?       
---------------------
 2024-03-01 00:00:00
(1 row)

PostgreSQL Differences

  • A fractional value combined with a separate field qualifier, such as interval '1.5' day, is rejected. PostgreSQL accepts it.
  • CedarDB accepts a fractional-second precision such as interval(0) but ignores it: values always keep microsecond resolution.
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