De-support floating-point timestamps.

Per discussion, the time has come to do this.  The handwriting has been
on the wall at least since 9.0 that this would happen someday, whenever
it got to be too much of a burden to support the float-timestamp option.
The triggering factor now is the discovery that there are multiple bugs
in the code that attempts to implement use of integer timestamps in the
replication protocol even when the server is built for float timestamps.
The internal float timestamps leak into the protocol fields in places.
While we could fix the identified bugs, there's a very high risk of
introducing more.  Trying to build a wall that would positively prevent
mixing integer and float timestamps is more complexity than we want to
undertake to maintain a long-deprecated option.  The fact that these
bugs weren't found through testing also indicates a lack of interest
in float timestamps.

This commit disables configure's --disable-integer-datetimes switch
(it'll still accept --enable-integer-datetimes, though), removes direct
references to USE_INTEGER_DATETIMES, and removes discussion of float
timestamps from the user documentation.  A considerable amount of code is
rendered dead by this, but removing that will occur as separate mop-up.

Discussion: https://postgr.es/m/26788.1487455319@sss.pgh.pa.us

configure

@@ -1473,7 +1473,7 @@ Optional Features:
   --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
   --disable-integer-datetimes
-                          disable 64-bit integer date/time support
+                          obsolete option, no longer supported
   --enable-nls[=LANGUAGES]
                           enable Native Language Support
   --disable-rpath         do not embed shared library search path in
@@ -2984,10 +2984,10 @@ fi
 
 
 #
-# 64-bit integer date/time storage: enabled by default.
+# 64-bit integer date/time storage is now the only option, but to avoid
+# unnecessary breakage of build scripts, continue to accept an explicit
+# "--enable-integer-datetimes" switch.
 #
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with 64-bit integer date/time support" >&5
-$as_echo_n "checking whether to build with 64-bit integer date/time support... " >&6; }
 
 
 # Check whether --enable-integer-datetimes was given.
@@ -2995,12 +2995,10 @@ if test "${enable_integer_datetimes+set}" = set; then :
   enableval=$enable_integer_datetimes;
   case $enableval in
     yes)
-
-$as_echo "#define USE_INTEGER_DATETIMES 1" >>confdefs.h
-
+      :
       ;;
     no)
-      :
+      as_fn_error $? "--disable-integer-datetimes is no longer supported" "$LINENO" 5
       ;;
     *)
       as_fn_error $? "no argument expected for --enable-integer-datetimes option" "$LINENO" 5
@@ -3010,13 +3008,9 @@ $as_echo "#define USE_INTEGER_DATETIMES 1" >>confdefs.h
 else
   enable_integer_datetimes=yes
 
-$as_echo "#define USE_INTEGER_DATETIMES 1" >>confdefs.h
-
 fi
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $enable_integer_datetimes" >&5
-$as_echo "$enable_integer_datetimes" >&6; }
 
 
 #

configure.in

@@ -122,13 +122,13 @@ PGAC_ARG_REQ(with, libs,      [DIRS], [alternative spelling of --with-libraries]
 
 
 #
-# 64-bit integer date/time storage: enabled by default.
+# 64-bit integer date/time storage is now the only option, but to avoid
+# unnecessary breakage of build scripts, continue to accept an explicit
+# "--enable-integer-datetimes" switch.
 #
-AC_MSG_CHECKING([whether to build with 64-bit integer date/time support])
-PGAC_ARG_BOOL(enable, integer-datetimes, yes, [disable 64-bit integer date/time support],
-              [AC_DEFINE([USE_INTEGER_DATETIMES], 1,
-                         [Define to 1 if you want 64-bit integer timestamp and interval support. (--enable-integer-datetimes)])])
-AC_MSG_RESULT([$enable_integer_datetimes])
+PGAC_ARG_BOOL(enable, integer-datetimes, yes, [obsolete option, no longer supported],
+              [],
+              [AC_MSG_ERROR([--disable-integer-datetimes is no longer supported])])
 
 
 #

doc/src/sgml/config.sgml

@@ -7695,11 +7695,9 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
       </term>
       <listitem>
        <para>
-        Reports whether <productname>PostgreSQL</> was built with
-        support for 64-bit-integer dates and times.  This can be
-        disabled by configuring with <literal>--disable-integer-datetimes</>
-        when building <productname>PostgreSQL</>.  The default value is
-        <literal>on</literal>.
+        Reports whether <productname>PostgreSQL</> was built with support for
+        64-bit-integer dates and times.  As of <productname>PostgreSQL</> 10,
+        this is always <literal>on</literal>.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/datatype.sgml

@@ -1580,7 +1580,7 @@ SELECT E'\\xDEADBEEF';
         <entry>both date and time (no time zone)</entry>
         <entry>4713 BC</entry>
         <entry>294276 AD</entry>
-        <entry>1 microsecond / 14 digits</entry>
+        <entry>1 microsecond</entry>
        </row>
        <row>
         <entry><type>timestamp [ (<replaceable>p</replaceable>) ] with time zone</type></entry>
@@ -1588,7 +1588,7 @@ SELECT E'\\xDEADBEEF';
         <entry>both date and time, with time zone</entry>
         <entry>4713 BC</entry>
         <entry>294276 AD</entry>
-        <entry>1 microsecond / 14 digits</entry>
+        <entry>1 microsecond</entry>
        </row>
        <row>
         <entry><type>date</type></entry>
@@ -1604,15 +1604,15 @@ SELECT E'\\xDEADBEEF';
         <entry>time of day (no date)</entry>
         <entry>00:00:00</entry>
         <entry>24:00:00</entry>
-        <entry>1 microsecond / 14 digits</entry>
+        <entry>1 microsecond</entry>
        </row>
        <row>
         <entry><type>time [ (<replaceable>p</replaceable>) ] with time zone</type></entry>
         <entry>12 bytes</entry>
-        <entry>times of day only, with time zone</entry>
+        <entry>time of day (no date), with time zone</entry>
         <entry>00:00:00+1459</entry>
         <entry>24:00:00-1459</entry>
-        <entry>1 microsecond / 14 digits</entry>
+        <entry>1 microsecond</entry>
        </row>
        <row>
         <entry><type>interval [ <replaceable>fields</replaceable> ] [ (<replaceable>p</replaceable>) ]</type></entry>
@@ -1620,7 +1620,7 @@ SELECT E'\\xDEADBEEF';
         <entry>time interval</entry>
         <entry>-178000000 years</entry>
         <entry>178000000 years</entry>
-        <entry>1 microsecond / 14 digits</entry>
+        <entry>1 microsecond</entry>
        </row>
       </tbody>
      </tgroup>
@@ -1643,41 +1643,7 @@ SELECT E'\\xDEADBEEF';
     <replaceable>p</replaceable> which specifies the number of
     fractional digits retained in the seconds field. By default, there
     is no explicit bound on precision.  The allowed range of
-    <replaceable>p</replaceable> is from 0 to 6 for the
-    <type>timestamp</type> and <type>interval</type> types.
-   </para>
-
-   <note>
-   <para>
-    When <type>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 <type>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 <type>timestamp</type> values to be represented than
-    shown above: from 4713 BC up to 5874897 AD.
-   </para>
-
-   <para>
-    The same compile-time option also determines whether
-    <type>time</type> and <type>interval</type> values are stored as
-    floating-point numbers or eight-byte integers.  In the
-    floating-point case, large <type>interval</type> values degrade in
-    precision as the size of the interval increases.
-   </para>
-   </note>
-
-   <para>
-    For the <type>time</type> types, the allowed range of
-    <replaceable>p</replaceable> is from 0 to 6 when eight-byte integer
-    storage is used, or from 0 to 10 when floating-point storage is used.
+    <replaceable>p</replaceable> is from 0 to 6.
    </para>
 
    <para>
@@ -1760,9 +1726,10 @@ MINUTE TO SECOND
      specification giving the number of
      fractional digits in the seconds field. Precision can be
      specified for <type>time</type>, <type>timestamp</type>, and
-     <type>interval</type> types.  The allowed values are mentioned
-     above.  If no precision is specified in a constant specification,
-     it defaults to the precision of the literal value.
+     <type>interval</type> types, and can range from 0 to 6.
+     If no precision is specified in a constant specification,
+     it defaults to the precision of the literal value (but not
+     more than 6 digits).
     </para>
 
     <sect3>

doc/src/sgml/installation.sgml

@@ -955,28 +955,6 @@ su - postgres
        </listitem>
       </varlistentry>
 
-      <varlistentry>
-       <term><option>--disable-integer-datetimes</option></term>
-       <listitem>
-        <para>
-         Disable support for 64-bit integer storage for timestamps and
-         intervals, and store datetime values as floating-point
-         numbers instead. Floating-point datetime storage was the
-         default in <productname>PostgreSQL</productname> releases
-         prior to 8.4, but it is now deprecated, because it does not
-         support microsecond precision for the full range of
-         <type>timestamp</type> values. However, integer-based
-         datetime storage requires a 64-bit integer type. Therefore,
-         this option can be used when no such type is available, or
-         for compatibility with applications written for prior
-         versions of <productname>PostgreSQL</productname>. See
-         <![%standalone-include[the documentation about datetime datatypes]]>
-         <![%standalone-ignore[<xref linkend="datatype-datetime">]]>
-         for more information.
-        </para>
-       </listitem>
-      </varlistentry>
-
       <varlistentry>
        <term><option>--disable-float4-byval</option></term>
        <listitem>

src/include/c.h

@@ -340,10 +340,11 @@ typedef unsigned PG_INT128_TYPE uint128;
 #define PG_INT64_MAX	INT64CONST(0x7FFFFFFFFFFFFFFF)
 #define PG_UINT64_MAX	UINT64CONST(0xFFFFFFFFFFFFFFFF)
 
-/* Select timestamp representation (float8 or int64) */
-#ifdef USE_INTEGER_DATETIMES
+/*
+ * We now always use int64 timestamps, but keep this symbol defined for the
+ * benefit of external code that might test it.
+ */
 #define HAVE_INT64_TIMESTAMP
-#endif
 
 /*
  * Size

src/include/pg_config.h.in

@@ -831,10 +831,6 @@
    (--enable-float8-byval) */
 #undef USE_FLOAT8_BYVAL
 
-/* Define to 1 if you want 64-bit integer timestamp and interval support.
-   (--enable-integer-datetimes) */
-#undef USE_INTEGER_DATETIMES
-
 /* Define to 1 to build with LDAP support. (--with-ldap) */
 #undef USE_LDAP
 

src/include/pg_config.h.win32

@@ -625,10 +625,6 @@
 /* Define to use /dev/urandom for random number generation */
 /* #undef USE_DEV_URANDOM */
 
-/* Define to 1 if you want 64-bit integer timestamp and interval support.
-   (--enable-integer-datetimes) */
-/* #undef USE_INTEGER_DATETIMES */
-
 /* Define to 1 to build with LDAP support. (--with-ldap) */
 /* #undef USE_LDAP */
 

src/interfaces/ecpg/include/ecpg_config.h.in

@@ -10,10 +10,6 @@
 /* Define to 1 if `long long int' works and is 64 bits. */
 #undef HAVE_LONG_LONG_INT_64
 
-/* Define to 1 if you want 64-bit integer timestamp and interval support.
-   (--enable-integer-datetimes) */
-#undef USE_INTEGER_DATETIMES
-
 /* Define to 1 to build client libraries as thread-safe code.
  *    (--enable-thread-safety) */
 #undef ENABLE_THREAD_SAFETY

src/interfaces/ecpg/include/pgtypes_interval.h

@@ -20,9 +20,7 @@ typedef long long int int64;
 #error must have a working 64-bit integer datatype
 #endif
 
-#ifdef USE_INTEGER_DATETIMES
 #define HAVE_INT64_TIMESTAMP
-#endif
 #endif   /* C_H */
 
 typedef struct

src/interfaces/ecpg/test/expected/pgtypeslib-dt_test2.c

@@ -145,10 +145,8 @@ main(void)
 				sprintf(t, "%s %s", dates[i], times[j]);
 				ts1 = PGTYPEStimestamp_from_asc(t, NULL);
 				text = PGTYPEStimestamp_to_asc(ts1);
-				/* skip outputs sensitive to USE_INTEGER_DATETIMES */
-				if (i != 19 || (j != 3 && j != 4))
-					printf("TS[%d,%d]: %s\n",
-						i, j, errno ? "-" : text);
+				printf("TS[%d,%d]: %s\n",
+				       i, j, errno ? "-" : text);
 				free(text);
 				free(t);
 			}

src/interfaces/ecpg/test/expected/pgtypeslib-dt_test2.stdout

@@ -103,6 +103,8 @@ Date[19]: 0099-01-08 BC (N - F)
 TS[19,0]: 0099-01-08 00:04:00 BC
 TS[19,1]: 0099-01-08 01:59:00 BC
 TS[19,2]: 0099-01-08 13:24:40 BC
+TS[19,3]: 0099-01-08 13:24:40.495 BC
+TS[19,4]: 0099-01-08 13:24:40.123456 BC
 Date[20]: - (N - T)
 Date[21]: - (N - T)
 interval[0]: @ 1 min

src/interfaces/ecpg/test/pgtypeslib/dt_test2.pgc

@@ -110,10 +110,8 @@ main(void)
 				sprintf(t, "%s %s", dates[i], times[j]);
 				ts1 = PGTYPEStimestamp_from_asc(t, NULL);
 				text = PGTYPEStimestamp_to_asc(ts1);
-				/* skip outputs sensitive to USE_INTEGER_DATETIMES */
-				if (i != 19 || (j != 3 && j != 4))
-					printf("TS[%d,%d]: %s\n",
-						i, j, errno ? "-" : text);
+				printf("TS[%d,%d]: %s\n",
+				       i, j, errno ? "-" : text);
 				free(text);
 				free(t);
 			}

src/tools/msvc/Solution.pm

@@ -28,9 +28,6 @@ sub _new
 	$self->DeterminePlatform();
 	my $bits = $self->{platform} eq 'Win32' ? 32 : 64;
 
-	# integer_datetimes is now the default
-	$options->{integer_datetimes} = 1
-	  unless exists $options->{integer_datetimes};
 	$options->{float4byval} = 1
 	  unless exists $options->{float4byval};
 	$options->{float8byval} = ($bits == 64)
@@ -169,8 +166,6 @@ s{PG_VERSION_STR "[^"]+"}{__STRINGIFY(x) #x\n#define __STRINGIFY2(z) __STRINGIFY
 		print O "#ifndef IGNORE_CONFIGURED_SETTINGS\n";
 		print O "#define USE_ASSERT_CHECKING 1\n"
 		  if ($self->{options}->{asserts});
-		print O "#define USE_INTEGER_DATETIMES 1\n"
-		  if ($self->{options}->{integer_datetimes});
 		print O "#define USE_LDAP 1\n"    if ($self->{options}->{ldap});
 		print O "#define HAVE_LIBZ 1\n"   if ($self->{options}->{zlib});
 		print O "#define USE_OPENSSL 1\n" if ($self->{options}->{openssl});
@@ -427,8 +422,6 @@ s{PG_VERSION_STR "[^"]+"}{__STRINGIFY(x) #x\n#define __STRINGIFY2(z) __STRINGIFY
 #define HAVE_LONG_LONG_INT_64
 #define ENABLE_THREAD_SAFETY 1
 EOF
-		print O "#define USE_INTEGER_DATETIMES 1\n"
-		  if ($self->{options}->{integer_datetimes});
 		print O "#endif\n";
 		close(O);
 	}
@@ -661,8 +654,6 @@ sub GetFakeConfigure
 
 	my $cfg = '--enable-thread-safety';
 	$cfg .= ' --enable-cassert' if ($self->{options}->{asserts});
-	$cfg .= ' --enable-integer-datetimes'
-	  if ($self->{options}->{integer_datetimes});
 	$cfg .= ' --enable-nls'       if ($self->{options}->{nls});
 	$cfg .= ' --enable-tap-tests' if ($self->{options}->{tap_tests});
 	$cfg .= ' --with-ldap'        if ($self->{options}->{ldap});

src/tools/msvc/config_default.pl

@@ -4,7 +4,6 @@ use warnings;
 
 our $config = {
 	asserts => 0,    # --enable-cassert
-	  # integer_datetimes=>1,   # --enable-integer-datetimes - on is now default
 	  # float4byval=>1,         # --disable-float4-byval, on by default
 
 	# float8byval=> $platformbits == 64, # --disable-float8-byval,