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postgres/doc/src/sgml/ref/alter_statistics.sgml
Peter Eisentraut 9081bddbd7 Improve <xref> vs. <command> formatting in the documentation
SQL commands are generally marked up as <command>, except when a link
to a reference page is used using <xref>.  But the latter doesn't
create monospace markup, so this looks strange especially when a
paragraph contains a mix of links and non-links.

We considered putting <command> in the <refentrytitle> on the target
side, but that creates some formatting side effects elsewhere.
Generally, it seems safer to solve this on the link source side.

We can't put the <xref> inside the <command>; the DTD doesn't allow
this.  DocBook 5 would allow the <command> to have the linkend
attribute itself, but we are not there yet.

So to solve this for now, convert the <xref>s to <link> plus
<command>.  This gives the correct look and also gives some more
flexibility what we can put into the link text (e.g., subcommands or
other clauses).  In the future, these could then be converted to
DocBook 5 style.

I haven't converted absolutely all xrefs to SQL command reference
pages, only those where we care about the appearance of the link text
or where it was otherwise appropriate to make the appearance match a
bit better.  Also in some cases, the links where repetitive, so in
those cases the links where just removed and replaced by a plain
<command>.  In cases where we just want the link and don't
specifically care about the generated link text (typically phrased
"for further information see <xref ...>") the xref is kept.

Reported-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://www.postgresql.org/message-id/flat/87o8pco34z.fsf@wibble.ilmari.org
2020-10-03 16:40:02 +02:00

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<!--
doc/src/sgml/ref/alter_statistics.sgml
PostgreSQL documentation
-->
<refentry id="sql-alterstatistics">
<indexterm zone="sql-alterstatistics">
<primary>ALTER STATISTICS</primary>
</indexterm>
<refmeta>
<refentrytitle>ALTER STATISTICS</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>ALTER STATISTICS</refname>
<refpurpose>
change the definition of an extended statistics object
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
ALTER STATISTICS <replaceable class="parameter">name</replaceable> OWNER TO { <replaceable class="parameter">new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER STATISTICS <replaceable class="parameter">name</replaceable> RENAME TO <replaceable class="parameter">new_name</replaceable>
ALTER STATISTICS <replaceable class="parameter">name</replaceable> SET SCHEMA <replaceable class="parameter">new_schema</replaceable>
ALTER STATISTICS <replaceable class="parameter">name</replaceable> SET STATISTICS <replaceable class="parameter">new_target</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>ALTER STATISTICS</command> changes the parameters of an existing
extended statistics object. Any parameters not specifically set in the
<command>ALTER STATISTICS</command> command retain their prior settings.
</para>
<para>
You must own the statistics object to use <command>ALTER STATISTICS</command>.
To change a statistics object's schema, you must also
have <literal>CREATE</literal> privilege on the new schema.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <literal>CREATE</literal> privilege on
the statistics object's schema. (These restrictions enforce that altering
the owner doesn't do anything you couldn't do by dropping and recreating
the statistics object. However, a superuser can alter ownership of any
statistics object anyway.)
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the statistics object to be
altered.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_owner</replaceable></term>
<listitem>
<para>
The user name of the new owner of the statistics object.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_name</replaceable></term>
<listitem>
<para>
The new name for the statistics object.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_schema</replaceable></term>
<listitem>
<para>
The new schema for the statistics object.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_target</replaceable></term>
<listitem>
<para>
The statistic-gathering target for this statistics object for subsequent
<link linkend="sql-analyze"><command>ANALYZE</command></link> operations.
The target can be set in the range 0 to 10000; alternatively, set it
to -1 to revert to using the maximum of the statistics target of the
referenced columns, if set, or the system default statistics
target (<xref linkend="guc-default-statistics-target"/>).
For more information on the use of statistics by the
<productname>PostgreSQL</productname> query planner, refer to
<xref linkend="planner-stats"/>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
There is no <command>ALTER STATISTICS</command> command in the SQL standard.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-createstatistics"/></member>
<member><xref linkend="sql-dropstatistics"/></member>
</simplelist>
</refsect1>
</refentry>