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Teach genbki.pl to auto-generate pg_type entries for array types.

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This eliminates some more tedium in adding new catalog entries,
specifically the need to set up an array type when adding a new
built-in data type.  Now it's sufficient to assign an OID for the
array type and write it in an "array_type_oid" metadata field.
You don't have to fill the base type's typarray link explicitly, either.

No catversion bump since the contents of pg_type aren't changed.
(Well, their order might be different, but that doesn't matter.)

John Naylor, reviewed and whacked around a bit by
Dagfinn Ilmari Mannsåker, and some more by me.

Discussion: https://postgr.es/m/CAJVSVGVTb6m9pJF49b3SuA8J+T-THO9c0hxOmoyv-yGKh-FbNg@mail.gmail.com
This commit is contained in:
Tom Lane
2018-09-20 15:14:46 -04:00
parent 09e99ce86e
commit 3dc820c43e
7 changed files with 419 additions and 646 deletions
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52
doc/src/sgml/bki.sgml
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@ -217,12 +217,14 @@
<replaceable>value</replaceable> pairs. The
allowed <replaceable>key</replaceable>s are the names of the catalog's
columns, plus the metadata keys <literal>oid</literal>,
<literal>oid_symbol</literal>, and <literal>descr</literal>.
<literal>oid_symbol</literal>,
<literal>array_type_oid</literal>, and <literal>descr</literal>.
(The use of <literal>oid</literal> and <literal>oid_symbol</literal>
is described in <xref linkend="system-catalog-oid-assignment"/>
below. <literal>descr</literal> supplies a description string for
the object, which will be inserted
into <structname>pg_description</structname>
is described in <xref linkend="system-catalog-oid-assignment"/> below,
while <literal>array_type_oid</literal> is described in
<xref linkend="system-catalog-auto-array-types"/>.
<literal>descr</literal> supplies a description string for the object,
which will be inserted into <structname>pg_description</structname>
or <structname>pg_shdescription</structname> as appropriate.)
While the metadata keys are optional, the catalog's defined columns
must all be provided, except when the catalog's <literal>.h</literal>
@ -282,8 +284,9 @@
<para>
Within each pair of curly braces, the metadata
fields <literal>oid</literal>, <literal>oid_symbol</literal>,
and <literal>descr</literal> (if present) come first, in that
order, then the catalog's own fields appear in their defined order.
<literal>array_type_oid</literal>, and <literal>descr</literal>
(if present) come first, in that order, then the catalog's own
fields appear in their defined order.
</para>
</listitem>
@ -498,6 +501,41 @@
</para>
</sect2>
<sect2 id="system-catalog-auto-array-types">
<title>Automatic Creation of Array Types</title>
<para>
Most scalar data types should have a corresponding array type (that is,
a standard varlena array type whose element type is the scalar type, and
which is referenced by the <structfield>typarray</structfield> field of
the scalar type's <structname>pg_type</structname>
entry). <filename>genbki.pl</filename> is able to generate
the <structname>pg_type</structname> entry for the array type
automatically in most cases.
</para>
<para>
To use this facility, just write an <literal>array_type_oid
=&gt; <replaceable>nnnn</replaceable></literal> metadata field in the
scalar type's <structname>pg_type</structname> entry, specifying the OID
to use for the array type. You may then omit
the <structfield>typarray</structfield> field, since it will be filled
automatically with that OID.
</para>
<para>
The generated array type's name is the scalar type's name with an
underscore prepended. The array entry's other fields are filled from
<literal>BKI_ARRAY_DEFAULT(<replaceable>value</replaceable>)</literal>
annotations in <filename>pg_type.h</filename>, or if there isn't one,
copied from the scalar type. (There's also a special case
for <structfield>typalign</structfield>.) Then
the <structfield>typelem</structfield>
and <structfield>typarray</structfield> fields of the two entries are
set to cross-reference each other.
</para>
</sect2>
<sect2 id="system-catalog-recipes">
<title>Recipes for Editing Data Files</title>