From e511d878f3bbc205cd260a79740e646eea3c1cd3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 29 Mar 2016 17:09:21 -0400
Subject: Allow to_timestamp(float8) to convert float infinity to timestamp
 infinity.

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
---
 doc/src/sgml/func.sgml | 50 ++++++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index e6c4ee52ee1..1bc9fbc4f51 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -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>
 
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