Re: [HACKERS] [PATCH] Fix for documentation of timestamp type

[Robert Haas]

On Tue, Dec 13, 2016 at 10:46 AM, Robert Haas  wrote:
> On Tue, Dec 13, 2016 at 10:41 AM, Tom Lane  wrote:
>> Robert Haas  writes:
>>> I find this a bit unclear, because the revised text kind of jumps back
>>> and forth between the floating-point and integer formats.  Perhaps
>>> something like this:
>>
>> Your wording seems OK to me, although I'd drop the "instead".
>
> Good idea.

Committed.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] [PATCH] Fix for documentation of timestamp type

[Cynthia Shang]

The latest patch attachment has a couple typos in it ("storead" instead of 
"stored"). I interpreted the final suggestion in the thread to mean 1) default 
stores in microseconds 2) deprecated compile-time option stores as seconds.  If 
these assumptions are correct then the suggestion in the thread (minus 
"instead" as Tom suggested) provided below should be incorporated and attached 
as a patch to this thread. Therefore I recommend an "Awaiting Author" status.

When timestamp values are stored as eight-byte integers (currently the 
default), microsecond precision is available over the full range of values.  In 
this case, the internal representation is the number of microseconds before or 
after midnight 2000-01-01. When timestamp values are stored as double 
precision floating-point numbers (a deprecated compile-time option), the 
internal representation is the number of seconds before or after midnight 
2000-01-01.  With this representation, the effective limit of precision might 
be less than 6; in practice, microsecond precision is achieved for dates within 
a few years of 2000-01-01, but the precision degrades for dates further away. 
Note that using floating-point datetimes allows a larger range of 
timestamp values to be represented than shown above: from 4713 BC 
up to 5874897 AD.

Thanks,
-Cynthia


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Re: [HACKERS] [PATCH] Fix for documentation of timestamp type

[Robert Haas]

On Tue, Dec 13, 2016 at 10:41 AM, Tom Lane  wrote:
> Robert Haas  writes:
>> I find this a bit unclear, because the revised text kind of jumps back
>> and forth between the floating-point and integer formats.  Perhaps
>> something like this:
>
> Your wording seems OK to me, although I'd drop the "instead".

Good idea.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] [PATCH] Fix for documentation of timestamp type

[Tom Lane]

Robert Haas  writes:
> I find this a bit unclear, because the revised text kind of jumps back
> and forth between the floating-point and integer formats.  Perhaps
> something like this:

Your wording seems OK to me, although I'd drop the "instead".

regards, tom lane


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Re: [HACKERS] [PATCH] Fix for documentation of timestamp type

[Robert Haas]

On Mon, Dec 12, 2016 at 8:50 AM, Aleksander Alekseev
 wrote:
> I suggest to rewrite the documentation a bit to make it more clear that
> by default timestamp is stored in microseconds. Corresponding patch is
> attached.

I find this a bit unclear, because the revised text kind of jumps back
and forth between the floating-point and integer formats.  Perhaps
something like this:

When timestamp values are stored as eight-byte integers
(currently the default), microsecond precision is available over
the full range of values.  In this case, the internal representation is the
number of microseconds before or after midnight 2000-01-01.
When timestamp values are
stored as double precision floating-point numbers instead (a
deprecated compile-time option), the internal representation is the number
of seconds before or after midnight 2000-01-01.  With this representation,
the effective limit of precision might be less than 6; in practice,
microsecond precision is achieved for dates within a few
years of 2000-01-01, but the precision degrades for dates further
away. Note that using floating-point datetimes allows a larger
range of timestamp values to be represented than
shown above: from 4713 BC up to 5874897 AD.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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