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Clean up to ensure tag completion as required by the newest versions

Browse Source 
of Norm's Modular Style Sheets and jade/docbook.
From Vince Vielhaber <vev@michvhf.com>.
This commit is contained in:
Thomas G. Lockhart
1998-12-29 02:24:47 +00:00
parent 6d7735e7f0
commit a75f2d21a8
115 changed files with 10587 additions and 8000 deletions
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152
doc/src/sgml/ref/create_operator.sgml
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@@ -12,7 +12,7 @@
<REFPURPOSE>
Defines a new user operator
</REFPURPOSE>
</refnamediv>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-09-09</DATE>
@@ -155,16 +155,19 @@ Operator to use for sorting.
Outputs
</TITLE>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the operator is successfully created.
</VARIABLELIST>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the operator is successfully created.
</para>
</listitem>
</varlistentry>
</VARIABLELIST>
</para>
</REFSECT2>
</REFSYNOPSISDIV>
@@ -176,25 +179,25 @@ Operator to use for sorting.
Description
</TITLE>
<PARA>
<command>CREATE OPERATOR</command> defines a new operator,
<replaceable class="parameter">name</replaceable>.
The user who defines an operator becomes its owner.
</para>
<para>
The operator <replaceable class="parameter">name</replaceable>
is a sequence of up to thirty two (32) characters in any combination
from the following:
<literallayout>
+ - * / &lt; &gt; = ~ ! @ # % ^ & | ` ? $ :
</literallayout>
<note>
<para>
No alphabetic characters are allowed in an operator name.
This enables <productname>Postgres</productname> to parse SQL input
into tokens without requiring spaces between each token.
</note>
</para>
<command>CREATE OPERATOR</command> defines a new operator,
<replaceable class="parameter">name</replaceable>.
The user who defines an operator becomes its owner.
</para>
<para>
The operator <replaceable class="parameter">name</replaceable>
is a sequence of up to thirty two (32) characters in any combination
from the following:
<literallayout>
+ - * / &lt; &gt; = ~ ! @ # % ^ & | ` ? $ :
</literallayout>
<note>
<para>
No alphabetic characters are allowed in an operator name.
This enables <productname>Postgres</productname> to parse SQL input
into tokens without requiring spaces between each token.
</para>
</note>
</para>
<para>
The operator "!=" is mapped to "&lt;&gt;" on input, so they are
therefore equivalent.
@@ -206,26 +209,26 @@ into tokens without requiring spaces between each token.
unary operators only RIGHTARG should be defined.
</para>
<para>
Also, the
<replaceable class="parameter">func_name</replaceable> procedure must have
Also, the
<replaceable class="parameter">func_name</replaceable> procedure must have
been previously defined using <command>CREATE FUNCTION</command> and must
be defined to accept the correct number of arguments
(either one or two).
(either one or two).
</para>
<para>
The commutator operator is present so that
<productname>Postgres</productname> can
<productname>Postgres</productname> can
reverse the order of the operands if it wishes.
For example, the operator area-less-than, &lt;&lt;&lt;,
would have a commutator
operator, area-greater-than, &gt;&gt;&gt;.
Hence, the query optimizer could freely convert:
For example, the operator area-less-than, &lt;&lt;&lt;,
would have a commutator
operator, area-greater-than, &gt;&gt;&gt;.
Hence, the query optimizer could freely convert:
<programlisting>
"0,0,1,1"::box &gt;&gt;&gt; MYBOXES.description
"0,0,1,1"::box &gt;&gt;&gt; MYBOXES.description
</programlisting>
to
<programlisting>
MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box</programlisting>
MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box</programlisting>
</para>
<para>
This allows the execution code to always use the latter
@@ -233,21 +236,21 @@ MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box</programlisting>
what.
</para>
<para>
Suppose that an
Suppose that an
operator, area-equal, ===, exists, as well as an area not
equal, !==.
The negator operator allows the query optimizer to convert
<programlisting>
NOT MYBOXES.description === "0,0,1,1"::box
NOT MYBOXES.description === "0,0,1,1"::box
</programlisting>
to
<programlisting>
MYBOXES.description !== "0,0,1,1"::box
MYBOXES.description !== "0,0,1,1"::box
</programlisting>
</para>
<para>
If a commutator operator name is supplied,
<productname>Postgres</productname>
<productname>Postgres</productname>
searches for it in the catalog. If it is found and it
does not yet have a commutator itself, then the commutator's
entry is updated to have the current (new) operator
@@ -264,22 +267,22 @@ MYBOXES.description !== "0,0,1,1"::box
<para>
The next two specifications are present to support the
query optimizer in performing joins.
<productname>Postgres</productname> can always
<productname>Postgres</productname> can always
evaluate a join (i.e., processing a clause with two tuple
variables separated by an operator that returns a boolean)
by iterative substitution [WONG76].
In addition, <productname>Postgres</productname>
In addition, <productname>Postgres</productname>
is planning on implementing a hash-join algorithm along
the lines of [SHAP86]; however, it must know whether this
strategy is applicable.
For example, a hash-join
For example, a hash-join
algorithm is usable for a clause of the form:
<programlisting>
MYBOXES.description === MYBOXES2.description
MYBOXES.description === MYBOXES2.description
</programlisting>
but not for a clause of the form:
<programlisting>
MYBOXES.description &lt;&lt;&lt; MYBOXES2.description.
MYBOXES.description &lt;&lt;&lt; MYBOXES2.description.
</programlisting>
The HASHES flag gives the needed information to the query
optimizer concerning whether a hash join strategy is
@@ -292,13 +295,13 @@ MYBOXES.description &lt;&lt;&lt; MYBOXES2.description.
sort both relations using the operator, &lt;&lt;&lt;. On the other
hand, merge-sort is not usable with the clause:
<programlisting>
MYBOXES.description &lt;&lt;&lt; MYBOXES2.description
MYBOXES.description &lt;&lt;&lt; MYBOXES2.description
</programlisting>
</para>
<para>
If other join strategies are found to be practical,
<productname>Postgres</productname>
will change the optimizer and run-time system to use
<productname>Postgres</productname>
will change the optimizer and run-time system to use
them and will require additional specification when an
operator is defined. Fortunately, the research community
invents new join strategies infrequently, and the added
@@ -310,14 +313,14 @@ MYBOXES.description &lt;&lt;&lt; MYBOXES2.description
the query optimizer can estimate result sizes. If a
clause of the form:
<programlisting>
MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box
MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box
</programlisting>
is present in the qualification,
then <productname>Postgres</productname> may have to
then <productname>Postgres</productname> may have to
estimate the fraction of the instances in MYBOXES that
satisfy the clause. The function
<replaceable class="parameter">res_proc</replaceable>
must be a registered function (meaning it is already defined using
<replaceable class="parameter">res_proc</replaceable>
must be a registered function (meaning it is already defined using
define function(l)) which accepts one argument of the correct
data type and returns a floating point number. The
query optimizer simply calls this function, passing the
@@ -335,14 +338,14 @@ MYBOXES.description &lt;&lt;&lt; "0,0,1,1"::box
<para>
The difference between the function
<programlisting>
my_procedure_1 (MYBOXES.description, "0,0,1,1"::box)
my_procedure_1 (MYBOXES.description, "0,0,1,1"::box)
</programlisting>
and the operator
<programlisting>
MYBOXES.description === "0,0,1,1"::box
MYBOXES.description === "0,0,1,1"::box
</programlisting>
is that <productname>Postgres</productname>
attempts to optimize operators and can
attempts to optimize operators and can
decide to use an index to restrict the search space when
operators are involved. However, there is no attempt to
optimize functions, and they are performed by brute force.
@@ -359,12 +362,13 @@ MYBOXES.description === "0,0,1,1"::box
</TITLE>
<PARA>
Refer to the chapter on operators in the
<citetitle>PostgreSQL User's Guide</citetitle>
<citetitle>PostgreSQL User's Guide</citetitle>
for further information.
Refer to <command>DROP OPERATOR</command> to delete
user-defined operators from a database.
user-defined operators from a database.
</para>
</REFSECT2>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATEOPERATOR-2">
<TITLE>
@@ -374,19 +378,17 @@ user-defined operators from a database.
area-equality, for the BOX data type.
</PARA>
<ProgramListing>
CREATE OPERATOR === (
LEFTARG = box,
RIGHTARG = box,
PROCEDURE = area_equal_procedure,
COMMUTATOR = ===,
NEGATOR = !==,
RESTRICT = area_restriction_procedure,
HASHES,
JOIN = area-join-procedure,
SORT = <<<, <<<)
</ProgramListing>
CREATE OPERATOR === (
LEFTARG = box,
RIGHTARG = box,
PROCEDURE = area_equal_procedure,
COMMUTATOR = ===,
NEGATOR = !==,
RESTRICT = area_restriction_procedure,
HASHES,
JOIN = area-join-procedure,
SORT = <<<, <<<)
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEOPERATOR-3">