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docs: remove use of escape strings and use bytea hex output

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standard_conforming_strings defaulted to 'on' in PG 9.1.
bytea_output defaulted to 'hex' in PG 9.0.

Reported-by: André Hänsel

Discussion: https://postgr.es/m/12e601d447ac$345994a0$9d0cbde0$@webkr.de

Backpatch-through: 9.3
pull/34/head
Bruce Momjian 7 years ago
parent e8fe426baa
commit f77de4b0c0
5 changed files with 72 additions and 80 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 27
      doc/src/sgml/array.sgml
  2. 71
      doc/src/sgml/datatype.sgml
  3. 48
      doc/src/sgml/func.sgml
  4. 4
      doc/src/sgml/lobj.sgml
  5. 2
      doc/src/sgml/rowtypes.sgml

27
doc/src/sgml/array.sgml
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@ -766,9 +766,9 @@ SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2
For example, elements containing curly braces, commas (or the data type's
delimiter character), double quotes, backslashes, or leading or trailing
whitespace must be double-quoted. Empty strings and strings matching the
word <literal>NULL</literal> must be quoted, too. To put a double quote or
backslash in a quoted array element value, use escape string syntax
and precede it with a backslash. Alternatively, you can avoid quotes and use
word <literal>NULL</literal> must be quoted, too. To put a double
quote or backslash in a quoted array element value, precede it
with a backslash. Alternatively, you can avoid quotes and use
backslash-escaping to protect all data characters that would otherwise
be taken as array syntax.
</para>
@ -781,27 +781,6 @@ SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2
non-whitespace characters of an element, is not ignored.
</para>
<note>
<para>
Remember that what you write in an SQL command will first be interpreted
as a string literal, and then as an array. This doubles the number of
backslashes you need. For example, to insert a <type>text</type> array
value containing a backslash and a double quote, you'd need to write:
<programlisting>
INSERT ... VALUES (E'{"\\\\","\\""}');
</programlisting>
The escape string processor removes one level of backslashes, so that
what arrives at the array-value parser looks like <literal>{"\\","\""}</literal>.
In turn, the strings fed to the <type>text</type> data type's input routine
become <literal>\</literal> and <literal>"</literal> respectively. (If we were working
with a data type whose input routine also treated backslashes specially,
<type>bytea</type> for example, we might need as many as eight backslashes
in the command to get one backslash into the stored array element.)
Dollar quoting (see <xref linkend="sql-syntax-dollar-quoting"/>) can be
used to avoid the need to double backslashes.
</para>
</note>
<tip>
<para>
The <literal>ARRAY</literal> constructor syntax (see

71
doc/src/sgml/datatype.sgml
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@ -1296,7 +1296,7 @@ SELECT b, char_length(b) FROM test2;
strings are distinguished from character strings in two
ways. First, binary strings specifically allow storing
octets of value zero and other <quote>non-printable</quote>
octets (usually, octets outside the range 32 to 126).
octets (usually, octets outside the decimal range 32 to 126).
Character strings disallow zero octets, and also disallow any
other octet values and sequences of octet values that are invalid
according to the database's selected character set encoding.
@ -1308,9 +1308,10 @@ SELECT b, char_length(b) FROM test2;
</para>
<para>
The <type>bytea</type> type supports two external formats for
input and output: <productname>PostgreSQL</productname>'s historical
<quote>escape</quote> format, and <quote>hex</quote> format. Both
The <type>bytea</type> type supports two
formats for input and output: <quote>hex</quote> format
and <productname>PostgreSQL</productname>'s historical
<quote>escape</quote> format. Both
of these are always accepted on input. The output format depends
on the configuration parameter <xref linkend="guc-bytea-output"/>;
the default is hex. (Note that the hex format was introduced in
@ -1348,7 +1349,7 @@ SELECT b, char_length(b) FROM test2;
<para>
Example:
<programlisting>
SELECT E'\\xDEADBEEF';
SELECT '\xDEADBEEF';
</programlisting>
</para>
</sect2>
@ -1368,7 +1369,7 @@ SELECT E'\\xDEADBEEF';
convenient. But in practice it is usually confusing because it
fuzzes up the distinction between binary strings and character
strings, and also the particular escape mechanism that was chosen is
somewhat unwieldy. So this format should probably be avoided
somewhat unwieldy. Therefore, this format should probably be avoided
for most new applications.
</para>
@ -1381,7 +1382,7 @@ SELECT E'\\xDEADBEEF';
octal value and precede it
by a backslash (or two backslashes, if writing the value as a
literal using escape string syntax).
Backslash itself (octet value 92) can alternatively be represented by
Backslash itself (octet decimal value 92) can alternatively be represented by
double backslashes.
<xref linkend="datatype-binary-sqlesc"/>
shows the characters that must be escaped, and gives the alternative
@ -1405,33 +1406,33 @@ SELECT E'\\xDEADBEEF';
<row>
<entry>0</entry>
<entry>zero octet</entry>
<entry><literal>E'\\000'</literal></entry>
<entry><literal>SELECT E'\\000'::bytea;</literal></entry>
<entry><literal>\000</literal></entry>
<entry><literal>'\000'</literal></entry>
<entry><literal>SELECT '\000'::bytea;</literal></entry>
<entry><literal>\x00</literal></entry>
</row>
<row>
<entry>39</entry>
<entry>single quote</entry>
<entry><literal>''''</literal> or <literal>E'\\047'</literal></entry>
<entry><literal>SELECT E'\''::bytea;</literal></entry>
<entry><literal>'</literal></entry>
<entry><literal>''''</literal> or <literal>'\047'</literal></entry>
<entry><literal>SELECT ''''::bytea;</literal></entry>
<entry><literal>\x27</literal></entry>
</row>
<row>
<entry>92</entry>
<entry>backslash</entry>
<entry><literal>E'\\\\'</literal> or <literal>E'\\134'</literal></entry>
<entry><literal>SELECT E'\\\\'::bytea;</literal></entry>
<entry><literal>\\</literal></entry>
<entry><literal>'\'</literal> or <literal>'\\134'</literal></entry>
<entry><literal>SELECT '\\'::bytea;</literal></entry>
<entry><literal>\x5c</literal></entry>
</row>
<row>
<entry>0 to 31 and 127 to 255</entry>
<entry><quote>non-printable</quote> octets</entry>
<entry><literal>E'\\<replaceable>xxx'</replaceable></literal> (octal value)</entry>
<entry><literal>SELECT E'\\001'::bytea;</literal></entry>
<entry><literal>\001</literal></entry>
<entry><literal>'\<replaceable>xxx'</replaceable></literal> (octal value)</entry>
<entry><literal>SELECT '\001'::bytea;</literal></entry>
<entry><literal>\x01</literal></entry>
</row>
</tbody>
@ -1459,7 +1460,7 @@ SELECT E'\\xDEADBEEF';
of escaping.) The remaining backslash is then recognized by the
<type>bytea</type> input function as starting either a three
digit octal value or escaping another backslash. For example,
a string literal passed to the server as <literal>E'\\001'</literal>
a string literal passed to the server as <literal>'\001'</literal>
becomes <literal>\001</literal> after passing through the
escape string parser. The <literal>\001</literal> is then sent
to the <type>bytea</type> input function, where it is converted
@ -1470,12 +1471,24 @@ SELECT E'\\xDEADBEEF';
</para>
<para>
<type>Bytea</type> octets are sometimes escaped when output. In general, each
<quote>non-printable</quote> octet is converted into
its equivalent three-digit octal value and preceded by one backslash.
Most <quote>printable</quote> octets are represented by their standard
representation in the client character set. The octet with decimal
value 92 (backslash) is doubled in the output.
<type>Bytea</type> octets are output in <literal>hex</literal>
format by default. If you change <xref linkend="guc-bytea-output"/>
to <literal>escape</literal>,
<quote>non-printable</quote> octet are converted to
equivalent three-digit octal value and preceded by one backslash.
Most <quote>printable</quote> octets are output by their standard
representation in the client character set, e.g.:
<programlisting>
SET bytea_output = 'escape';
SELECT 'abc \153\154\155 \052\251\124'::bytea;
bytea
----------------
abc klm *\251T
</programlisting>
The octet with decimal value 92 (backslash) is doubled in the output.
Details are in <xref linkend="datatype-binary-resesc"/>.
</para>
@ -1498,7 +1511,7 @@ SELECT E'\\xDEADBEEF';
<entry>92</entry>
<entry>backslash</entry>
<entry><literal>\\</literal></entry>
<entry><literal>SELECT E'\\134'::bytea;</literal></entry>
<entry><literal>SELECT '\134'::bytea;</literal></entry>
<entry><literal>\\</literal></entry>
</row>
@ -1506,7 +1519,7 @@ SELECT E'\\xDEADBEEF';
<entry>0 to 31 and 127 to 255</entry>
<entry><quote>non-printable</quote> octets</entry>
<entry><literal>\<replaceable>xxx</replaceable></literal> (octal value)</entry>
<entry><literal>SELECT E'\\001'::bytea;</literal></entry>
<entry><literal>SELECT '\001'::bytea;</literal></entry>
<entry><literal>\001</literal></entry>
</row>
@ -1514,7 +1527,7 @@ SELECT E'\\xDEADBEEF';
<entry>32 to 126</entry>
<entry><quote>printable</quote> octets</entry>
<entry>client character set representation</entry>
<entry><literal>SELECT E'\\176'::bytea;</literal></entry>
<entry><literal>SELECT '\176'::bytea;</literal></entry>
<entry><literal>~</literal></entry>
</row>

48
doc/src/sgml/func.sgml
Unescape View File

@ -1776,7 +1776,7 @@
octal sequences (<literal>\</literal><replaceable>nnn</replaceable>) and
doubles backslashes.
</entry>
<entry><literal>encode(E'123\\000\\001', 'base64')</literal></entry>
<entry><literal>encode('123\000\001', 'base64')</literal></entry>
<entry><literal>MTIzAAE=</literal></entry>
</row>
@ -2100,7 +2100,7 @@
the delimiter. See <xref linkend="functions-posix-regexp"/> for more
information.
</entry>
<entry><literal>regexp_split_to_array('hello world', E'\\s+')</literal></entry>
<entry><literal>regexp_split_to_array('hello world', '\s+')</literal></entry>
<entry><literal>{hello,world}</literal></entry>
</row>
@ -2117,7 +2117,7 @@
the delimiter. See <xref linkend="functions-posix-regexp"/> for more
information.
</entry>
<entry><literal>regexp_split_to_table('hello world', E'\\s+')</literal></entry>
<entry><literal>regexp_split_to_table('hello world', '\s+')</literal></entry>
<entry><literal>hello</literal><para><literal>world</literal></para> (2 rows)</entry>
</row>
@ -3301,8 +3301,8 @@ SELECT format('Testing %s, %s, %s, %%', 'one', 'two', 'three');
SELECT format('INSERT INTO %I VALUES(%L)', 'Foo bar', E'O\'Reilly');
<lineannotation>Result: </lineannotation><computeroutput>INSERT INTO "Foo bar" VALUES('O''Reilly')</computeroutput>
SELECT format('INSERT INTO %I VALUES(%L)', 'locations', E'C:\\Program Files');
<lineannotation>Result: </lineannotation><computeroutput>INSERT INTO locations VALUES(E'C:\\Program Files')</computeroutput>
SELECT format('INSERT INTO %I VALUES(%L)', 'locations', 'C:\Program Files');
<lineannotation>Result: </lineannotation><computeroutput>INSERT INTO locations VALUES('C:\Program Files')</computeroutput>
</screen>
</para>
@ -3429,7 +3429,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<secondary>concatenation</secondary>
</indexterm>
</entry>
<entry><literal>E'\\\\Post'::bytea || E'\\047gres\\000'::bytea</literal></entry>
<entry><literal>'\\Post'::bytea || '\047gres\000'::bytea</literal></entry>
<entry><literal>\\Post'gres\000</literal></entry>
</row>
@ -3442,7 +3442,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
</entry>
<entry><type>int</type></entry>
<entry>Number of bytes in binary string</entry>
<entry><literal>octet_length(E'jo\\000se'::bytea)</literal></entry>
<entry><literal>octet_length('jo\000se'::bytea)</literal></entry>
<entry><literal>5</literal></entry>
</row>
@ -3457,7 +3457,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Replace substring
</entry>
<entry><literal>overlay(E'Th\\000omas'::bytea placing E'\\002\\003'::bytea from 2 for 3)</literal></entry>
<entry><literal>overlay('Th\000omas'::bytea placing '\002\003'::bytea from 2 for 3)</literal></entry>
<entry><literal>T\\002\\003mas</literal></entry>
</row>
@ -3470,7 +3470,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
</entry>
<entry><type>int</type></entry>
<entry>Location of specified substring</entry>
<entry><literal>position(E'\\000om'::bytea in E'Th\\000omas'::bytea)</literal></entry>
<entry><literal>position('\000om'::bytea in 'Th\000omas'::bytea)</literal></entry>
<entry><literal>3</literal></entry>
</row>
@ -3485,7 +3485,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Extract substring
</entry>
<entry><literal>substring(E'Th\\000omas'::bytea from 2 for 3)</literal></entry>
<entry><literal>substring('Th\000omas'::bytea from 2 for 3)</literal></entry>
<entry><literal>h\000o</literal></entry>
</row>
@ -3504,7 +3504,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<parameter>bytes</parameter> from the start
and end of <parameter>string</parameter>
</entry>
<entry><literal>trim(E'\\000\\001'::bytea from E'\\000Tom\\001'::bytea)</literal></entry>
<entry><literal>trim('\000\001'::bytea from '\000Tom\001'::bytea)</literal></entry>
<entry><literal>Tom</literal></entry>
</row>
</tbody>
@ -3547,7 +3547,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<parameter>bytes</parameter> from the start and end of
<parameter>string</parameter>
</entry>
<entry><literal>btrim(E'\\000trim\\001'::bytea, E'\\000\\001'::bytea)</literal></entry>
<entry><literal>btrim('\000trim\001'::bytea, '\000\001'::bytea)</literal></entry>
<entry><literal>trim</literal></entry>
</row>
@ -3564,7 +3564,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
Decode binary data from textual representation in <parameter>string</parameter>.
Options for <parameter>format</parameter> are same as in <function>encode</function>.
</entry>
<entry><literal>decode(E'123\\000456', 'escape')</literal></entry>
<entry><literal>decode('123\000456', 'escape')</literal></entry>
<entry><literal>123\000456</literal></entry>
</row>
@ -3584,7 +3584,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
octal sequences (<literal>\</literal><replaceable>nnn</replaceable>) and
doubles backslashes.
</entry>
<entry><literal>encode(E'123\\000456'::bytea, 'escape')</literal></entry>
<entry><literal>encode('123\000456'::bytea, 'escape')</literal></entry>
<entry><literal>123\000456</literal></entry>
</row>
@ -3599,7 +3599,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Extract bit from string
</entry>
<entry><literal>get_bit(E'Th\\000omas'::bytea, 45)</literal></entry>
<entry><literal>get_bit('Th\000omas'::bytea, 45)</literal></entry>
<entry><literal>1</literal></entry>
</row>
@ -3614,7 +3614,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Extract byte from string
</entry>
<entry><literal>get_byte(E'Th\\000omas'::bytea, 4)</literal></entry>
<entry><literal>get_byte('Th\000omas'::bytea, 4)</literal></entry>
<entry><literal>109</literal></entry>
</row>
@ -3638,7 +3638,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<see>binary strings, length</see>
</indexterm>
</entry>
<entry><literal>length(E'jo\\000se'::bytea)</literal></entry>
<entry><literal>length('jo\000se'::bytea)</literal></entry>
<entry><literal>5</literal></entry>
</row>
@ -3654,7 +3654,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
Calculates the MD5 hash of <parameter>string</parameter>,
returning the result in hexadecimal
</entry>
<entry><literal>md5(E'Th\\000omas'::bytea)</literal></entry>
<entry><literal>md5('Th\000omas'::bytea)</literal></entry>
<entry><literal>8ab2d3c9689aaf18&#x200B;b4958c334c82d8b1</literal></entry>
</row>
@ -3670,7 +3670,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Set bit in string
</entry>
<entry><literal>set_bit(E'Th\\000omas'::bytea, 45, 0)</literal></entry>
<entry><literal>set_bit('Th\000omas'::bytea, 45, 0)</literal></entry>
<entry><literal>Th\000omAs</literal></entry>
</row>
@ -3686,7 +3686,7 @@ SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<entry>
Set byte in string
</entry>
<entry><literal>set_byte(E'Th\\000omas'::bytea, 4, 64)</literal></entry>
<entry><literal>set_byte('Th\000omas'::bytea, 4, 64)</literal></entry>
<entry><literal>Th\000o@as</literal></entry>
</row>
@ -4377,7 +4377,7 @@ regexp_replace('foobarbaz', 'b..', 'X')
<lineannotation>fooXbaz</lineannotation>
regexp_replace('foobarbaz', 'b..', 'X', 'g')
<lineannotation>fooXX</lineannotation>
regexp_replace('foobarbaz', 'b(..)', E'X\\1Y', 'g')
regexp_replace('foobarbaz', 'b(..)', 'X\1Y', 'g')
<lineannotation>fooXarYXazY</lineannotation>
</programlisting>
</para>
@ -4513,7 +4513,7 @@ SELECT col1, (SELECT regexp_matches(col2, '(bar)(beque)')) FROM tab;
Some examples:
<programlisting>
SELECT foo FROM regexp_split_to_table('the quick brown fox jumps over the lazy dog', E'\\s+') AS foo;
SELECT foo FROM regexp_split_to_table('the quick brown fox jumps over the lazy dog', '\s+') AS foo;
foo
-------
the
@ -4527,13 +4527,13 @@ SELECT foo FROM regexp_split_to_table('the quick brown fox jumps over the lazy d
dog
(9 rows)
SELECT regexp_split_to_array('the quick brown fox jumps over the lazy dog', E'\\s+');
SELECT regexp_split_to_array('the quick brown fox jumps over the lazy dog', '\s+');
regexp_split_to_array
-----------------------------------------------
{the,quick,brown,fox,jumps,over,the,lazy,dog}
(1 row)
SELECT foo FROM regexp_split_to_table('the quick brown fox', E'\\s*') AS foo;
SELECT foo FROM regexp_split_to_table('the quick brown fox', '\s*') AS foo;
foo
-----
t

4
doc/src/sgml/lobj.sgml
Unescape View File

@ -568,7 +568,7 @@ int lo_unlink(PGconn *conn, Oid lobjId);
Create a large object and store data there, returning its OID.
Pass <literal>0</literal> to have the system choose an OID.
</entry>
<entry><literal>lo_from_bytea(0, E'\\xffffff00')</literal></entry>
<entry><literal>lo_from_bytea(0, '\xffffff00')</literal></entry>
<entry><literal>24528</literal></entry>
</row>
@ -583,7 +583,7 @@ int lo_unlink(PGconn *conn, Oid lobjId);
<entry>
Write data at the given offset.
</entry>
<entry><literal>lo_put(24528, 1, E'\\xaa')</literal></entry>
<entry><literal>lo_put(24528, 1, '\xaa')</literal></entry>
<entry></entry>
</row>

2
doc/src/sgml/rowtypes.sgml
Unescape View File

@ -510,7 +510,7 @@ SELECT c.somefunc FROM inventory_item c;
containing a double quote and a backslash in a composite
value, you'd need to write:
<programlisting>
INSERT ... VALUES (E'("\\"\\\\")');
INSERT ... VALUES ('("\"\\")');
</programlisting>
The string-literal processor removes one level of backslashes, so that
what arrives at the composite-value parser looks like

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