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Allow to_timestamp(float8) to convert float infinity to timestamp infinity.

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With the original SQL-function implementation, such cases failed because
we don't support infinite intervals.  Converting the function to C lets
us bypass the interval representation, which should be a bit faster as
well as more flexible.

Vitaly Burovoy, reviewed by Anastasia Lubennikova
This commit is contained in:
Tom Lane
2016-03-29 17:09:21 -04:00
parent 96f8373cad
commit e511d878f3
7 changed files with 149 additions and 26 deletions
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50
doc/src/sgml/func.sgml
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@ -5579,15 +5579,6 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
argument is the value to be formatted and the second argument is a
template that defines the output or input format.
</para>
<para>
A single-argument <function>to_timestamp</function> function is also
available; it accepts a
<type>double precision</type> argument and converts from Unix epoch
(seconds since 1970-01-01 00:00:00+00) to
<type>timestamp with time zone</type>.
(<type>Integer</type> Unix epochs are implicitly cast to
<type>double precision</type>.)
</para>
<table id="functions-formatting-table">
<title>Formatting Functions</title>
@ -5670,16 +5661,17 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
<entry>convert string to time stamp</entry>
<entry><literal>to_timestamp('05&nbsp;Dec&nbsp;2000', 'DD&nbsp;Mon&nbsp;YYYY')</literal></entry>
</row>
<row>
<entry><literal><function>to_timestamp(<type>double precision</type>)</function></literal></entry>
<entry><type>timestamp with time zone</type></entry>
<entry>convert Unix epoch to time stamp</entry>
<entry><literal>to_timestamp(1284352323)</literal></entry>
</row>
</tbody>
</tgroup>
</table>
<note>
<para>
There is also a single-argument <function>to_timestamp</function>
function; see <xref linkend="functions-datetime-table">.
</para>
</note>
<para>
In a <function>to_char</> output template string, there are certain
patterns that are recognized and replaced with appropriately-formatted
@ -7060,8 +7052,8 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
<entry><type>timestamp with time zone</type></entry>
<entry>
Create timestamp with time zone from year, month, day, hour, minute
and seconds fields. When <parameter>timezone</parameter> is not specified,
then current time zone is used.
and seconds fields; if <parameter>timezone</parameter> is not
specified, the current time zone is used
</entry>
<entry><literal>make_timestamptz(2013, 7, 15, 8, 15, 23.5)</literal></entry>
<entry><literal>2013-07-15 08:15:23.5+01</literal></entry>
@ -7127,6 +7119,19 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
<entry></entry>
<entry></entry>
</row>
<row>
<entry>
<indexterm>
<primary>to_timestamp</primary>
</indexterm>
<literal><function>to_timestamp(<type>double precision</type>)</function></literal>
</entry>
<entry><type>timestamp with time zone</type></entry>
<entry>Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to
timestamp</entry>
<entry><literal>to_timestamp(1284352323)</literal></entry>
<entry><literal>2010-09-13 04:32:03+00</literal></entry>
</row>
</tbody>
</tgroup>
</table>
@ -7377,16 +7382,13 @@ SELECT EXTRACT(EPOCH FROM INTERVAL '5 days 3 hours');
</screen>
<para>
Here is how you can convert an epoch value back to a time
stamp:
You can convert an epoch value back to a time stamp
with <function>to_timestamp</>:
</para>
<screen>
SELECT TIMESTAMP WITH TIME ZONE 'epoch' + 982384720.12 * INTERVAL '1 second';
SELECT to_timestamp(982384720.12);
<lineannotation>Result: </lineannotation><computeroutput>2001-02-17 04:38:40.12+00</computeroutput>
</screen>
<para>
(The <function>to_timestamp</> function encapsulates the above
conversion.)
</para>
</listitem>
</varlistentry>