Add date_bin function

Similar to date_trunc, but allows binning by an arbitrary interval
rather than just full units.

Author: John Naylor <john.naylor@enterprisedb.com>
Reviewed-by: David Fetter <david@fetter.org>
Reviewed-by: Isaac Morland <isaac.morland@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Artur Zakirov <zaartur@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CACPNZCt4buQFRgy6DyjuZS-2aPDpccRkrJBmgUfwYc1KiaXYxg@mail.gmail.com

doc/src/sgml/func.sgml

@@ -8730,6 +8730,20 @@ SELECT regexp_match('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
         </para></entry>
        </row>
 
+       <row>
+        <entry role="func_table_entry"><para role="func_signature">
+         <function>date_bin</function> ( <type>interval</type>, <type>timestamp</type>, <type>timestamp</type> )
+         <returnvalue>timestamp</returnvalue>
+        </para>
+        <para>
+         Bin input into specified interval aligned with specified origin; see <xref linkend="functions-datetime-bin"/>
+        </para>
+        <para>
+         <literal>date_bin('15 minutes', timestamp '2001-02-16 20:38:40', timestamp '2001-02-16 20:05:00')</literal>
+         <returnvalue>2001-02-16 20:35:00</returnvalue>
+        </para></entry>
+       </row>
+
        <row>
         <entry role="func_table_entry"><para role="func_signature">
          <indexterm>
@@ -9868,6 +9882,42 @@ SELECT date_trunc('hour', INTERVAL '3 days 02:47:33');
    </para>
   </sect2>
 
+  <sect2 id="functions-datetime-bin">
+   <title><function>date_bin</function></title>
+
+   <indexterm>
+    <primary>date_bin</primary>
+   </indexterm>
+
+   <para>
+    The function <function>date_bin</function> <quote>bins</quote> the input
+    timestamp into the specified interval (the <firstterm>stride</firstterm>)
+    aligned with a specified origin.
+   </para>
+
+   <para>
+    Examples:
+<screen>
+SELECT date_bin('15 minutes', TIMESTAMP '2020-02-11 15:44:17', TIMESTAMP '2001-01-01');
+<lineannotation>Result: </lineannotation><computeroutput>2020-02-11 15:30:00</computeroutput>
+
+SELECT date_bin('15 minutes', TIMESTAMP '2020-02-11 15:44:17', TIMESTAMP '2001-01-01 00:02:30');
+<lineannotation>Result: </lineannotation><computeroutput>2020-02-11 15:32:30</computeroutput>
+</screen>
+   </para>
+
+   <para>
+    In cases full units (1 minute, 1 hour, etc.), it gives the same result as
+    the analogous <function>date_trunc</function> call, but the difference is
+    that <function>date_bin</function> can truncate to an arbitrary interval.
+   </para>
+
+   <para>
+    The <parameter>stride</parameter> interval cannot contain units of month
+    or larger.
+   </para>
+  </sect2>
+
   <sect2 id="functions-datetime-zoneconvert">
    <title><literal>AT TIME ZONE</literal></title>
 

src/backend/utils/adt/timestamp.c

@@ -3812,6 +3812,43 @@ timestamptz_age(PG_FUNCTION_ARGS)
  *---------------------------------------------------------*/
 
 
+/* timestamp_bin()
+ * Bin timestamp into specified interval.
+ */
+Datum
+timestamp_bin(PG_FUNCTION_ARGS)
+{
+	Interval   *stride = PG_GETARG_INTERVAL_P(0);
+	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
+	Timestamp	origin = PG_GETARG_TIMESTAMP(2);
+	Timestamp	result,
+				tm_diff,
+				stride_usecs,
+				tm_delta;
+
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMP(timestamp);
+
+	if (TIMESTAMP_NOT_FINITE(origin))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+				 errmsg("origin out of range")));
+
+	if (stride->month != 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("timestamps cannot be binned into intervals containing months or years")));
+
+	stride_usecs = stride->day * USECS_PER_DAY + stride->time;
+
+	tm_diff = timestamp - origin;
+	tm_delta = tm_diff - tm_diff % stride_usecs;;
+
+	result = origin + tm_delta;
+
+	PG_RETURN_TIMESTAMP(result);
+}
+
 /* timestamp_trunc()
  * Truncate timestamp to specified units.
  */
@@ -3946,6 +3983,43 @@ timestamp_trunc(PG_FUNCTION_ARGS)
 	PG_RETURN_TIMESTAMP(result);
 }
 
+/* timestamptz_bin()
+ * Bin timestamptz into specified interval using specified origin.
+ */
+Datum
+timestamptz_bin(PG_FUNCTION_ARGS)
+{
+	Interval   *stride = PG_GETARG_INTERVAL_P(0);
+	TimestampTz timestamp = PG_GETARG_TIMESTAMPTZ(1);
+	TimestampTz	origin = PG_GETARG_TIMESTAMPTZ(2);
+	TimestampTz	result,
+				stride_usecs,
+				tm_diff,
+				tm_delta;
+
+	if (TIMESTAMP_NOT_FINITE(timestamp))
+		PG_RETURN_TIMESTAMPTZ(timestamp);
+
+	if (TIMESTAMP_NOT_FINITE(origin))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+				 errmsg("origin out of range")));
+
+	if (stride->month != 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("timestamps cannot be binned into intervals containing months or years")));
+
+	stride_usecs = stride->day * USECS_PER_DAY + stride->time;
+
+	tm_diff = timestamp - origin;
+	tm_delta = tm_diff - tm_diff % stride_usecs;;
+
+	result = origin + tm_delta;
+
+	PG_RETURN_TIMESTAMPTZ(result);
+}
+
 /*
  * Common code for timestamptz_trunc() and timestamptz_trunc_zone().
  *

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202103241
+#define CATALOG_VERSION_NO	202103242
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5813,6 +5813,17 @@
 { oid => '2020', descr => 'truncate timestamp to specified units',
   proname => 'date_trunc', prorettype => 'timestamp',
   proargtypes => 'text timestamp', prosrc => 'timestamp_trunc' },
+
+{ oid => '8990',
+  descr => 'bin timestamp into specified interval',
+  proname => 'date_bin', prorettype => 'timestamp',
+  proargtypes => 'interval timestamp timestamp',
+  prosrc => 'timestamp_bin' },
+{ oid => '8993',
+  descr => 'bin timestamp with time zone into specified interval',
+  proname => 'date_bin', prorettype => 'timestamptz',
+  proargtypes => 'interval timestamptz timestamptz', prosrc => 'timestamptz_bin' },
+
 { oid => '2021', descr => 'extract field from timestamp',
   proname => 'date_part', prorettype => 'float8',
   proargtypes => 'text timestamp', prosrc => 'timestamp_part' },

src/test/regress/expected/timestamp.out

@@ -545,6 +545,102 @@ SELECT date_trunc( 'week', timestamp '2004-02-29 15:44:17.71393' ) AS week_trunc
  Mon Feb 23 00:00:00 2004
 (1 row)
 
+-- verify date_bin behaves the same as date_trunc for relevant intervals
+-- case 1: AD dates, origin < input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '2001-01-01') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '2020-02-29 15:44:17.71393')) ts (ts);
+     str     | interval | equal 
+-------------+----------+-------
+ week        | 7 d      | t
+ day         | 1 d      | t
+ hour        | 1 h      | t
+ minute      | 1 m      | t
+ second      | 1 s      | t
+ millisecond | 1 ms     | t
+ microsecond | 1 us     | t
+(7 rows)
+
+-- case 2: BC dates, origin < input
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts) = date_bin(interval::interval, ts, timestamp '2000-01-01 BC') AS equal
+FROM (
+  VALUES
+  ('week', '7 d'),
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamp '0055-6-10 15:44:17.71393 BC')) ts (ts);
+     str     | interval | equal 
+-------------+----------+-------
+ week        | 7 d      | t
+ day         | 1 d      | t
+ hour        | 1 h      | t
+ minute      | 1 m      | t
+ second      | 1 s      | t
+ millisecond | 1 ms     | t
+ microsecond | 1 us     | t
+(7 rows)
+
+-- bin timestamps into arbitrary intervals
+SELECT
+  interval,
+  ts,
+  origin,
+  date_bin(interval::interval, ts, origin)
+FROM (
+  VALUES
+  ('15 days'),
+  ('2 hours'),
+  ('1 hour 30 minutes'),
+  ('15 minutes'),
+  ('10 seconds'),
+  ('100 milliseconds'),
+  ('250 microseconds')
+) intervals (interval),
+(VALUES (timestamp '2020-02-11 15:44:17.71393')) ts (ts),
+(VALUES (timestamp '2001-01-01')) origin (origin);
+     interval      |               ts               |          origin          |            date_bin            
+-------------------+--------------------------------+--------------------------+--------------------------------
+ 15 days           | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Thu Feb 06 00:00:00 2020
+ 2 hours           | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 14:00:00 2020
+ 1 hour 30 minutes | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 15:00:00 2020
+ 15 minutes        | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 15:30:00 2020
+ 10 seconds        | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 15:44:10 2020
+ 100 milliseconds  | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 15:44:17.7 2020
+ 250 microseconds  | Tue Feb 11 15:44:17.71393 2020 | Mon Jan 01 00:00:00 2001 | Tue Feb 11 15:44:17.71375 2020
+(7 rows)
+
+-- shift bins using the origin parameter:
+SELECT date_bin('5 min'::interval, timestamp '2020-02-01 01:01:01', timestamp '2020-02-01 00:02:30');
+         date_bin         
+--------------------------
+ Sat Feb 01 00:57:30 2020
+(1 row)
+
+-- disallow intervals with months or years
+SELECT date_bin('5 months'::interval, timestamp '2020-02-01 01:01:01', timestamp '2001-01-01');
+ERROR:  timestamps cannot be binned into intervals containing months or years
+SELECT date_bin('5 years'::interval,  timestamp '2020-02-01 01:01:01', timestamp '2001-01-01');
+ERROR:  timestamps cannot be binned into intervals containing months or years
 -- Test casting within a BETWEEN qualifier
 SELECT d1 - timestamp without time zone '1997-01-02' AS diff
   FROM TIMESTAMP_TBL

src/test/regress/expected/timestamptz.out

@@ -663,6 +663,72 @@ SELECT date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'VET
  Thu Feb 15 20:00:00 2001 PST
 (1 row)
 
+-- verify date_bin behaves the same as date_trunc for relevant intervals
+SELECT
+  str,
+  interval,
+  date_trunc(str, ts, 'Australia/Sydney') = date_bin(interval::interval, ts, timestamp with time zone '2001-01-01+11') AS equal
+FROM (
+  VALUES
+  ('day', '1 d'),
+  ('hour', '1 h'),
+  ('minute', '1 m'),
+  ('second', '1 s'),
+  ('millisecond', '1 ms'),
+  ('microsecond', '1 us')
+) intervals (str, interval),
+(VALUES (timestamptz '2020-02-29 15:44:17.71393+00')) ts (ts);
+     str     | interval | equal 
+-------------+----------+-------
+ day         | 1 d      | t
+ hour        | 1 h      | t
+ minute      | 1 m      | t
+ second      | 1 s      | t
+ millisecond | 1 ms     | t
+ microsecond | 1 us     | t
+(6 rows)
+
+-- bin timestamps into arbitrary intervals
+SELECT
+  interval,
+  ts,
+  origin,
+  date_bin(interval::interval, ts, origin)
+FROM (
+  VALUES
+  ('15 days'),
+  ('2 hours'),
+  ('1 hour 30 minutes'),
+  ('15 minutes'),
+  ('10 seconds'),
+  ('100 milliseconds'),
+  ('250 microseconds')
+) intervals (interval),
+(VALUES (timestamptz '2020-02-11 15:44:17.71393')) ts (ts),
+(VALUES (timestamptz '2001-01-01')) origin (origin);
+     interval      |                 ts                 |            origin            |              date_bin              
+-------------------+------------------------------------+------------------------------+------------------------------------
+ 15 days           | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Thu Feb 06 00:00:00 2020 PST
+ 2 hours           | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 14:00:00 2020 PST
+ 1 hour 30 minutes | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 15:00:00 2020 PST
+ 15 minutes        | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 15:30:00 2020 PST
+ 10 seconds        | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 15:44:10 2020 PST
+ 100 milliseconds  | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 15:44:17.7 2020 PST
+ 250 microseconds  | Tue Feb 11 15:44:17.71393 2020 PST | Mon Jan 01 00:00:00 2001 PST | Tue Feb 11 15:44:17.71375 2020 PST
+(7 rows)
+
+-- shift bins using the origin parameter:
+SELECT date_bin('5 min'::interval, timestamptz '2020-02-01 01:01:01+00', timestamptz '2020-02-01 00:02:30+00');
+           date_bin           
+------------------------------
+ Fri Jan 31 16:57:30 2020 PST
+(1 row)
+
+-- disallow intervals with months or years
+SELECT date_bin('5 months'::interval, timestamp with time zone '2020-02-01 01:01:01+00', timestamp with time zone '2001-01-01+00');
+ERROR:  timestamps cannot be binned into intervals containing months or years
+SELECT date_bin('5 years'::interval,  timestamp with time zone '2020-02-01 01:01:01+00', timestamp with time zone '2001-01-01+00');
+ERROR:  timestamps cannot be binned into intervals containing months or years
 -- Test casting within a BETWEEN qualifier
 SELECT d1 - timestamp with time zone '1997-01-02' AS diff
   FROM TIMESTAMPTZ_TBL