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Remove support for postfix (right-unary) operators.

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This feature has been a thorn in our sides for a long time, causing
many grammatical ambiguity problems.  It doesn't seem worth the
pain to continue to support it, so remove it.

There are some follow-on improvements we can make in the grammar,
but this commit only removes the bare minimum number of productions,
plus assorted backend support code.

Note that pg_dump and psql continue to have full support, since
they may be used against older servers.  However, pg_dump warns
about postfix operators.  There is also a check in pg_upgrade.

Documentation-wise, I (tgl) largely removed the "left unary"
terminology in favor of saying "prefix operator", which is
a more standard and IMO less confusing term.

I included a catversion bump, although no initial catalog data
changes here, to mark the boundary at which oprkind = 'r'
stopped being valid in pg_operator.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com
This commit is contained in:
Tom Lane
2020-09-17 19:38:05 -04:00
parent 76f412ab31
commit 1ed6b89563
32 changed files with 279 additions and 339 deletions
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16
doc/src/sgml/ref/drop_operator.sgml
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@@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
DROP OPERATOR [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ( { <replaceable class="parameter">left_type</replaceable> | NONE } , { <replaceable class="parameter">right_type</replaceable> | NONE } ) [, ...] [ CASCADE | RESTRICT ]
DROP OPERATOR [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ( { <replaceable class="parameter">left_type</replaceable> | NONE } , <replaceable class="parameter">right_type</replaceable> ) [, ...] [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@@ -73,8 +73,7 @@ DROP OPERATOR [ IF EXISTS ] <replaceable class="parameter">name</replaceable> (
<term><replaceable class="parameter">right_type</replaceable></term>
<listitem>
<para>
The data type of the operator's right operand; write
<literal>NONE</literal> if the operator has no right operand.
The data type of the operator's right operand.
</para>
</listitem>
</varlistentry>
@@ -113,24 +112,17 @@ DROP OPERATOR ^ (integer, integer);
</para>
<para>
Remove the left unary bitwise complement operator
Remove the bitwise-complement prefix operator
<literal>~b</literal> for type <type>bit</type>:
<programlisting>
DROP OPERATOR ~ (none, bit);
</programlisting>
</para>
<para>
Remove the right unary factorial operator <literal>x!</literal>
for type <type>bigint</type>:
<programlisting>
DROP OPERATOR ! (bigint, none);
</programlisting></para>
<para>
Remove multiple operators in one command:
<programlisting>
DROP OPERATOR ~ (none, bit), ! (bigint, none);
DROP OPERATOR ~ (none, bit), ^ (integer, integer);
</programlisting></para>
</refsect1>