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Add get_bit/set_bit functions for bit strings, paralleling those for bytea,
and implement OVERLAY() for bit strings and bytea. In passing also convert text OVERLAY() to a true built-in, instead of relying on a SQL function. Leonardo F, reviewed by Kevin Grittner
This commit is contained in:
Tom Lane
@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.497 2010/01/19 05:50:18 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.498 2010/01/25 20:55:32 tgl Exp $ -->
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<chapter id="functions">
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<title>Functions and Operators</title>
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@ -2620,7 +2620,7 @@
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<entry>Return Type</entry>
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<entry>Description</entry>
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<entry>Example</entry>
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<entry>Result</entry>
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<entry>Result</entry>
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</row>
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</thead>
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@ -2640,32 +2640,6 @@
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<entry><literal>\\Post'gres\000</literal></entry>
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</row>
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<row>
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<entry><function>get_bit</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</entry>
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<entry><type>int</type></entry>
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<entry>
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Extract bit from string
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<indexterm>
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<primary>get_bit</primary>
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</indexterm>
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</entry>
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<entry><literal>get_bit(E'Th\\000omas'::bytea, 45)</literal></entry>
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<entry><literal>1</literal></entry>
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</row>
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<row>
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<entry><function>get_byte</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</entry>
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<entry><type>int</type></entry>
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<entry>
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Extract byte from string
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<indexterm>
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<primary>get_byte</primary>
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</indexterm>
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</entry>
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<entry><literal>get_byte(E'Th\\000omas'::bytea, 4)</literal></entry>
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<entry><literal>109</literal></entry>
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</row>
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<row>
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<entry><literal><function>octet_length</function>(<parameter>string</parameter>)</literal></entry>
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<entry><type>int</type></entry>
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@ -2674,6 +2648,16 @@
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<entry><literal>5</literal></entry>
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</row>
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<row>
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<entry><literal><function>overlay</function>(<parameter>string</parameter> placing <parameter>string</parameter> from <type>int</type> <optional>for <type>int</type></optional>)</literal></entry>
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<entry><type>bytea</type></entry>
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<entry>
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Replace substring
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</entry>
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<entry><literal>overlay(E'Th\\000omas'::bytea placing E'\\002\\003'::bytea from 2 for 3)</literal></entry>
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<entry><literal>T\\002\\003mas</literal></entry>
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</row>
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<row>
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<entry><literal><function>position</function>(<parameter>substring</parameter> in <parameter>string</parameter>)</literal></entry>
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<entry><type>int</type></entry>
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@ -2682,34 +2666,6 @@
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<entry><literal>3</literal></entry>
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</row>
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<row>
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<entry><function>set_bit</function>(<parameter>string</parameter>,
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<parameter>offset</parameter>, <parameter>newvalue</>)</entry>
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<entry><type>bytea</type></entry>
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<entry>
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Set bit in string
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<indexterm>
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<primary>set_bit</primary>
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</indexterm>
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</entry>
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<entry><literal>set_bit(E'Th\\000omas'::bytea, 45, 0)</literal></entry>
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<entry><literal>Th\000omAs</literal></entry>
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</row>
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<row>
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<entry><function>set_byte</function>(<parameter>string</parameter>,
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<parameter>offset</parameter>, <parameter>newvalue</>)</entry>
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<entry><type>bytea</type></entry>
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<entry>
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Set byte in string
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<indexterm>
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<primary>set_byte</primary>
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</indexterm>
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</entry>
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<entry><literal>set_byte(E'Th\\000omas'::bytea, 4, 64)</literal></entry>
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<entry><literal>Th\000o@as</literal></entry>
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</row>
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<row>
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<entry><literal><function>substring</function>(<parameter>string</parameter> <optional>from <type>int</type></optional> <optional>for <type>int</type></optional>)</literal></entry>
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<entry><type>bytea</type></entry>
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@ -2784,7 +2740,7 @@
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</entry>
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<entry><type>bytea</type></entry>
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<entry>
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Decode binary string from <parameter>string</parameter> previously
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Decode binary string from <parameter>string</parameter> previously
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encoded with <function>encode</>. Parameter type is same as in <function>encode</>.
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</entry>
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<entry><literal>decode(E'123\\000456', 'escape')</literal></entry>
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@ -2805,6 +2761,36 @@
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<entry><literal>123\000456</literal></entry>
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</row>
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<row>
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<entry>
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<literal><function>get_bit</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</literal>
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</entry>
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<entry><type>int</type></entry>
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<entry>
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Extract bit from string
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<indexterm>
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<primary>get_bit</primary>
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</indexterm>
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</entry>
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<entry><literal>get_bit(E'Th\\000omas'::bytea, 45)</literal></entry>
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<entry><literal>1</literal></entry>
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</row>
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<row>
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<entry>
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<literal><function>get_byte</function>(<parameter>string</parameter>, <parameter>offset</parameter>)</literal>
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</entry>
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<entry><type>int</type></entry>
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<entry>
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Extract byte from string
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<indexterm>
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<primary>get_byte</primary>
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</indexterm>
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</entry>
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<entry><literal>get_byte(E'Th\\000omas'::bytea, 4)</literal></entry>
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<entry><literal>109</literal></entry>
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</row>
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<row>
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<entry><literal><function>length</function>(<parameter>string</parameter>)</literal></entry>
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<entry><type>int</type></entry>
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@ -2834,6 +2820,38 @@
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<entry><literal>md5(E'Th\\000omas'::bytea)</literal></entry>
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<entry><literal>8ab2d3c9689aaf18 b4958c334c82d8b1</literal></entry>
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</row>
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<row>
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<entry>
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<literal><function>set_bit</function>(<parameter>string</parameter>,
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<parameter>offset</parameter>, <parameter>newvalue</>)</literal>
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</entry>
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<entry><type>bytea</type></entry>
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<entry>
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Set bit in string
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<indexterm>
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<primary>set_bit</primary>
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</indexterm>
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</entry>
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<entry><literal>set_bit(E'Th\\000omas'::bytea, 45, 0)</literal></entry>
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<entry><literal>Th\000omAs</literal></entry>
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</row>
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<row>
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<entry>
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<literal><function>set_byte</function>(<parameter>string</parameter>,
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<parameter>offset</parameter>, <parameter>newvalue</>)</literal>
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</entry>
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<entry><type>bytea</type></entry>
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<entry>
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Set byte in string
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<indexterm>
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<primary>set_byte</primary>
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</indexterm>
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</entry>
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<entry><literal>set_byte(E'Th\\000omas'::bytea, 4, 64)</literal></entry>
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<entry><literal>Th\000o@as</literal></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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@ -2934,7 +2952,15 @@
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<literal><function>bit_length</function></literal>,
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<literal><function>octet_length</function></literal>,
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<literal><function>position</function></literal>,
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<literal><function>substring</function></literal>.
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<literal><function>substring</function></literal>,
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<literal><function>overlay</function></literal>.
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</para>
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<para>
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The following functions work on bit strings as well as binary
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strings:
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<literal><function>get_bit</function></literal>,
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<literal><function>set_bit</function></literal>.
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</para>
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<para>
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