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Commita6715af

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Add bit_count SQL function
This function for bit and bytea counts the set bits in the bit or bytestring. Internally, we use the existing popcount functionality.For the name, after some discussion, we settled on bit_count, whichalso exists with this meaning in MySQL, Java, and Python.Author: David Fetter <david@fetter.org>Discussion:https://www.postgresql.org/message-id/flat/20201230105535.GJ13234@fetter.org
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9 files changed

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9 files changed

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‎doc/src/sgml/func.sgml

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@@ -4010,6 +4010,28 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
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</thead>
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<tbody>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm>
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<primary>bit_count</primary>
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</indexterm>
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<indexterm>
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<primary>popcount</primary>
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<see>bit_count</see>
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</indexterm>
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<function>bit_count</function> ( <parameter>bytes</parameter> <type>bytea</type> )
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<returnvalue>bigint</returnvalue>
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</para>
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<para>
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Returns the number of bits set in the binary string (also known as
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<quote>popcount</quote>).
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</para>
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<para>
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<literal>bit_count('\x1234567890'::bytea)</literal>
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<returnvalue>31</returnvalue>
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</para></entry>
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</row>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm>
@@ -4714,6 +4736,24 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
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</thead>
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<tbody>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm>
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<primary>bit_count</primary>
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</indexterm>
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<function>bit_count</function> ( <type>bit</type> )
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<returnvalue>bigint</returnvalue>
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</para>
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<para>
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Returns the number of bits set in the bit string (also known as
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<quote>popcount</quote>).
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</para>
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<para>
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<literal>bit_count(B'10111')</literal>
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<returnvalue>4</returnvalue>
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</para></entry>
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</row>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm>

‎src/backend/utils/adt/varbit.c

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@@ -36,6 +36,7 @@
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#include"libpq/pqformat.h"
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#include"nodes/nodeFuncs.h"
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#include"nodes/supportnodes.h"
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#include"port/pg_bitutils.h"
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#include"utils/array.h"
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#include"utils/builtins.h"
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#include"utils/varbit.h"
@@ -1201,6 +1202,19 @@ bit_overlay(VarBit *t1, VarBit *t2, int sp, int sl)
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returnresult;
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}
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/*
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* bit_count
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*
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* Returns the number of bits set in a bit string.
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*/
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Datum
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bit_bit_count(PG_FUNCTION_ARGS)
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{
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VarBit*arg=PG_GETARG_VARBIT_P(0);
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PG_RETURN_INT64(pg_popcount((char*)VARBITS(arg),VARBITBYTES(arg)));
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}
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/*
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* bitlength, bitoctetlength
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* Return the length of a bit string

‎src/backend/utils/adt/varlena.c

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@@ -3440,6 +3440,17 @@ bytea_overlay(bytea *t1, bytea *t2, int sp, int sl)
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returnresult;
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}
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/*
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* bit_count
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*/
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Datum
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bytea_bit_count(PG_FUNCTION_ARGS)
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{
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bytea*t1=PG_GETARG_BYTEA_PP(0);
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PG_RETURN_INT64(pg_popcount(VARDATA_ANY(t1),VARSIZE_ANY_EXHDR(t1)));
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}
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/*
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* byteapos -
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* Return the position of the specified substring.

‎src/include/catalog/catversion.h

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@@ -53,6 +53,6 @@
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*/
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/*yyyymmddN */
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#defineCATALOG_VERSION_NO202103231
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#defineCATALOG_VERSION_NO202103232
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#endif

‎src/include/catalog/pg_proc.dat

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@@ -1446,6 +1446,9 @@
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{ oid => '752', descr => 'substitute portion of string',
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proname => 'overlay', prorettype => 'bytea',
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proargtypes => 'bytea bytea int4', prosrc => 'byteaoverlay_no_len' },
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{ oid => '8436', descr => 'number of set bits',
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proname => 'bit_count', prorettype => 'int8', proargtypes => 'bytea',
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prosrc => 'bytea_bit_count'},
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{ oid => '725',
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proname => 'dist_pl', prorettype => 'float8', proargtypes => 'point line',
@@ -3876,6 +3879,9 @@
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{ oid => '3033', descr => 'set bit',
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proname => 'set_bit', prorettype => 'bit', proargtypes => 'bit int4 int4',
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prosrc => 'bitsetbit' },
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{ oid => '8435', descr => 'number of set bits',
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proname => 'bit_count', prorettype => 'int8', proargtypes => 'bit',
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prosrc => 'bit_bit_count'},
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# for macaddr type support
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{ oid => '436', descr => 'I/O',

‎src/test/regress/expected/bit.out

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@@ -710,6 +710,19 @@ SELECT overlay(B'0101011100' placing '001' from 20);
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0101011100001
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(1 row)
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-- bit_count
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SELECT bit_count(B'0101011100'::bit(10));
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bit_count
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-----------
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5
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(1 row)
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SELECT bit_count(B'1111111111'::bit(10));
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bit_count
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-----------
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10
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(1 row)
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-- This table is intentionally left around to exercise pg_dump/pg_upgrade
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CREATE TABLE bit_defaults(
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b1 bit(4) DEFAULT '1001',

‎src/test/regress/expected/strings.out

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@@ -2227,3 +2227,9 @@ SELECT encode(overlay(E'Th\\000omas'::bytea placing E'\\002\\003'::bytea from 5
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Th\000o\x02\x03
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(1 row)
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SELECT bit_count('\x1234567890'::bytea);
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bit_count
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-----------
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31
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(1 row)
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‎src/test/regress/sql/bit.sql

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@@ -215,6 +215,10 @@ SELECT overlay(B'0101011100' placing '101' from 6);
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SELECT overlay(B'0101011100' placing'001'from11);
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SELECT overlay(B'0101011100' placing'001'from20);
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-- bit_count
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SELECT bit_count(B'0101011100'::bit(10));
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SELECT bit_count(B'1111111111'::bit(10));
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-- This table is intentionally left around to exercise pg_dump/pg_upgrade
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CREATETABLEbit_defaults(
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b1bit(4) DEFAULT'1001',

‎src/test/regress/sql/strings.sql

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@@ -742,3 +742,5 @@ SELECT btrim(E'\\000trim\\000'::bytea, ''::bytea);
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SELECT encode(overlay(E'Th\\000omas'::bytea placing E'Th\\001omas'::byteafrom2),'escape');
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SELECT encode(overlay(E'Th\\000omas'::bytea placing E'\\002\\003'::byteafrom8),'escape');
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SELECT encode(overlay(E'Th\\000omas'::bytea placing E'\\002\\003'::byteafrom5 for3),'escape');
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SELECT bit_count('\x1234567890'::bytea);

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