Add bit_xor aggregate function

This can be used as a checksum for unordered sets.  bit_and and bit_or
already exist.

Author: Alexey Bashtanov <bashtanov@imap.cc>
Reviewed-by: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/9d4582ae-ecfc-3a13-2238-6ab5a37c1f41@imap.cc

doc/src/sgml/func.sgml

@@ -19224,6 +19224,33 @@ SELECT NULLIF(value, '(none)') ...
        <entry>Yes</entry>
       </row>
 
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>bit_xor</primary>
+        </indexterm>
+        <function>bit_xor</function> ( <type>smallint</type> )
+        <returnvalue>smallint</returnvalue>
+       </para>
+       <para role="func_signature">
+        <function>bit_xor</function> ( <type>integer</type> )
+        <returnvalue>integer</returnvalue>
+       </para>
+       <para role="func_signature">
+        <function>bit_xor</function> ( <type>bigint</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para role="func_signature">
+        <function>bit_xor</function> ( <type>bit</type> )
+        <returnvalue>bit</returnvalue>
+       </para>
+       <para>
+        Computes the bitwise exclusive OR of all non-null input values.
+        Can be useful as a checksum for an unordered set of values.
+       </para></entry>
+       <entry>Yes</entry>
+      </row>
+
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202103032
+#define CATALOG_VERSION_NO	202103061
 
 #endif

src/include/catalog/pg_aggregate.dat

@@ -505,18 +505,26 @@
   aggcombinefn => 'int2and', aggtranstype => 'int2' },
 { aggfnoid => 'bit_or(int2)', aggtransfn => 'int2or', aggcombinefn => 'int2or',
   aggtranstype => 'int2' },
+{ aggfnoid => 'bit_xor(int2)', aggtransfn => 'int2xor', aggcombinefn => 'int2xor',
+  aggtranstype => 'int2' },
 { aggfnoid => 'bit_and(int4)', aggtransfn => 'int4and',
   aggcombinefn => 'int4and', aggtranstype => 'int4' },
 { aggfnoid => 'bit_or(int4)', aggtransfn => 'int4or', aggcombinefn => 'int4or',
   aggtranstype => 'int4' },
+{ aggfnoid => 'bit_xor(int4)', aggtransfn => 'int4xor', aggcombinefn => 'int4xor',
+  aggtranstype => 'int4' },
 { aggfnoid => 'bit_and(int8)', aggtransfn => 'int8and',
   aggcombinefn => 'int8and', aggtranstype => 'int8' },
 { aggfnoid => 'bit_or(int8)', aggtransfn => 'int8or', aggcombinefn => 'int8or',
   aggtranstype => 'int8' },
+{ aggfnoid => 'bit_xor(int8)', aggtransfn => 'int8xor', aggcombinefn => 'int8xor',
+  aggtranstype => 'int8' },
 { aggfnoid => 'bit_and(bit)', aggtransfn => 'bitand', aggcombinefn => 'bitand',
   aggtranstype => 'bit' },
 { aggfnoid => 'bit_or(bit)', aggtransfn => 'bitor', aggcombinefn => 'bitor',
   aggtranstype => 'bit' },
+{ aggfnoid => 'bit_xor(bit)', aggtransfn => 'bitxor', aggcombinefn => 'bitxor',
+  aggtranstype => 'bit' },
 
 # xml
 { aggfnoid => 'xmlagg', aggtransfn => 'xmlconcat2', aggtranstype => 'xml' },

src/include/catalog/pg_proc.dat

@@ -7995,24 +7995,36 @@
 { oid => '2237', descr => 'bitwise-or smallint aggregate',
   proname => 'bit_or', prokind => 'a', proisstrict => 'f', prorettype => 'int2',
   proargtypes => 'int2', prosrc => 'aggregate_dummy' },
+{ oid => '8452', descr => 'bitwise-xor smallint aggregate',
+  proname => 'bit_xor', prokind => 'a', proisstrict => 'f', prorettype => 'int2',
+  proargtypes => 'int2', prosrc => 'aggregate_dummy' },
 { oid => '2238', descr => 'bitwise-and integer aggregate',
   proname => 'bit_and', prokind => 'a', proisstrict => 'f',
   prorettype => 'int4', proargtypes => 'int4', prosrc => 'aggregate_dummy' },
 { oid => '2239', descr => 'bitwise-or integer aggregate',
   proname => 'bit_or', prokind => 'a', proisstrict => 'f', prorettype => 'int4',
   proargtypes => 'int4', prosrc => 'aggregate_dummy' },
+{ oid => '8453', descr => 'bitwise-xor integer aggregate',
+  proname => 'bit_xor', prokind => 'a', proisstrict => 'f', prorettype => 'int4',
+  proargtypes => 'int4', prosrc => 'aggregate_dummy' },
 { oid => '2240', descr => 'bitwise-and bigint aggregate',
   proname => 'bit_and', prokind => 'a', proisstrict => 'f',
   prorettype => 'int8', proargtypes => 'int8', prosrc => 'aggregate_dummy' },
 { oid => '2241', descr => 'bitwise-or bigint aggregate',
   proname => 'bit_or', prokind => 'a', proisstrict => 'f', prorettype => 'int8',
   proargtypes => 'int8', prosrc => 'aggregate_dummy' },
+{ oid => '8454', descr => 'bitwise-xor bigint aggregate',
+  proname => 'bit_xor', prokind => 'a', proisstrict => 'f', prorettype => 'int8',
+  proargtypes => 'int8', prosrc => 'aggregate_dummy' },
 { oid => '2242', descr => 'bitwise-and bit aggregate',
   proname => 'bit_and', prokind => 'a', proisstrict => 'f', prorettype => 'bit',
   proargtypes => 'bit', prosrc => 'aggregate_dummy' },
 { oid => '2243', descr => 'bitwise-or bit aggregate',
   proname => 'bit_or', prokind => 'a', proisstrict => 'f', prorettype => 'bit',
   proargtypes => 'bit', prosrc => 'aggregate_dummy' },
+{ oid => '8455', descr => 'bitwise-xor bit aggregate',
+  proname => 'bit_xor', prokind => 'a', proisstrict => 'f', prorettype => 'bit',
+  proargtypes => 'bit', prosrc => 'aggregate_dummy' },
 
 # formerly-missing interval + datetime operators
 { oid => '2546',

src/test/regress/expected/aggregates.out

@@ -742,11 +742,12 @@ CREATE TEMPORARY TABLE bitwise_test(
 -- empty case
 SELECT
   BIT_AND(i2) AS "?",
-  BIT_OR(i4)  AS "?"
+  BIT_OR(i4)  AS "?",
+  BIT_XOR(i8) AS "?"
 FROM bitwise_test;
- ? | ? 
----+---
-   |  
+ ? | ? | ? 
+---+---+---
+   |   |  
 (1 row)
 
 COPY bitwise_test FROM STDIN NULL 'null';
@@ -762,11 +763,17 @@ SELECT
   BIT_OR(i8)  AS "7",
   BIT_OR(i)   AS "?",
   BIT_OR(x)   AS "7",
-  BIT_OR(y)   AS "1101"
+  BIT_OR(y)   AS "1101",
+  BIT_XOR(i2) AS "5",
+  BIT_XOR(i4) AS "5",
+  BIT_XOR(i8) AS "5",
+  BIT_XOR(i)  AS "?",
+  BIT_XOR(x)  AS "7",
+  BIT_XOR(y)  AS "1101"
 FROM bitwise_test;
- 1 | 1 | 1 | ? | 0 | 0100 | 7 | 7 | 7 | ? | 7 | 1101 
----+---+---+---+---+------+---+---+---+---+---+------
- 1 | 1 | 1 | 1 | 0 | 0100 | 7 | 7 | 7 | 3 | 7 | 1101
+ 1 | 1 | 1 | ? | 0 | 0100 | 7 | 7 | 7 | ? | 7 | 1101 | 5 | 5 | 5 | ? | 7 | 1101 
+---+---+---+---+---+------+---+---+---+---+---+------+---+---+---+---+---+------
+ 1 | 1 | 1 | 1 | 0 | 0100 | 7 | 7 | 7 | 3 | 7 | 1101 | 5 | 5 | 5 | 2 | 7 | 1101
 (1 row)
 
 --

src/test/regress/sql/aggregates.sql

@@ -212,7 +212,8 @@ CREATE TEMPORARY TABLE bitwise_test(
 -- empty case
 SELECT
   BIT_AND(i2) AS "?",
-  BIT_OR(i4)  AS "?"
+  BIT_OR(i4)  AS "?",
+  BIT_XOR(i8) AS "?"
 FROM bitwise_test;
 
 COPY bitwise_test FROM STDIN NULL 'null';
@@ -234,7 +235,14 @@ SELECT
   BIT_OR(i8)  AS "7",
   BIT_OR(i)   AS "?",
   BIT_OR(x)   AS "7",
-  BIT_OR(y)   AS "1101"
+  BIT_OR(y)   AS "1101",
+
+  BIT_XOR(i2) AS "5",
+  BIT_XOR(i4) AS "5",
+  BIT_XOR(i8) AS "5",
+  BIT_XOR(i)  AS "?",
+  BIT_XOR(x)  AS "7",
+  BIT_XOR(y)  AS "1101"
 FROM bitwise_test;
 
 --