Interval resolution

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Hi,

I'm running PostgreSQL 7.4.6 on RHEL 4 Beta 2. There seems to be a
bug, or call it inconsistentcy with the documentation, in the
interval data type. According to
http://www.postgresql.org/docs/7.4/static/datatype-datetime.html, the
resolution of interval is 1 microsecond with a range from -178000000
to 178000000 years. In the example below, this resolution is not
provided:

<quote>
geertj(at)greet:~> psql
Welcome to psql 7.4.6, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help on internal slash commands
\g or terminate with semicolon to execute query
\q to quit

geertj=> create table test (iv interval);
CREATE TABLE
geertj=> insert into test values ('701868 days, 1:26:00.685041');
INSERT 22447 1
geertj=> select * from test;
iv
- --------------------------------
701868 days 01:26:00.685043335
(1 row)
</quote>

As you can see, there's an error of 2 microseconds. After a bit of
experimentation I've noticed that the error becomes larger when the
interval becomes bigger.

Now I don't know if this is a serious bug, and I only found it when
doing unit testing with random data. However, it is an inconsistency
with the documentation that states microsecond resolution is provided
over the entire range.

Regards,
Geert Jansen

- --
Geert Jansen <geert(at)boskant(dot)nl>
PGP fingerprint: 97FA CE01 F760 4FA9 A0EC F7F9 9ACF 9153 95E2 50E0

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