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Teach genbki.pl to auto-generate pg_type entries for array types.
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
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‎doc/src/sgml/bki.sgml

Lines changed: 45 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -217,12 +217,14 @@
217217
<replaceable>value</replaceable> pairs. The
218218
allowed <replaceable>key</replaceable>s are the names of the catalog's
219219
columns, plus the metadata keys <literal>oid</literal>,
220-
<literal>oid_symbol</literal>, and <literal>descr</literal>.
220+
<literal>oid_symbol</literal>,
221+
<literal>array_type_oid</literal>, and <literal>descr</literal>.
221222
(The use of <literal>oid</literal> and <literal>oid_symbol</literal>
222-
is described in <xref linkend="system-catalog-oid-assignment"/>
223-
below. <literal>descr</literal> supplies a description string for
224-
the object, which will be inserted
225-
into <structname>pg_description</structname>
223+
is described in <xref linkend="system-catalog-oid-assignment"/> below,
224+
while <literal>array_type_oid</literal> is described in
225+
<xref linkend="system-catalog-auto-array-types"/>.
226+
<literal>descr</literal> supplies a description string for the object,
227+
which will be inserted into <structname>pg_description</structname>
226228
or <structname>pg_shdescription</structname> as appropriate.)
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While the metadata keys are optional, the catalog's defined columns
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must all be provided, except when the catalog's <literal>.h</literal>
@@ -282,8 +284,9 @@
282284
<para>
283285
Within each pair of curly braces, the metadata
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fields <literal>oid</literal>, <literal>oid_symbol</literal>,
285-
and <literal>descr</literal> (if present) come first, in that
286-
order, then the catalog's own fields appear in their defined order.
287+
<literal>array_type_oid</literal>, and <literal>descr</literal>
288+
(if present) come first, in that order, then the catalog's own
289+
fields appear in their defined order.
287290
</para>
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</listitem>
289292

@@ -498,6 +501,41 @@
498501
</para>
499502
</sect2>
500503

504+
<sect2 id="system-catalog-auto-array-types">
505+
<title>Automatic Creation of Array Types</title>
506+
507+
<para>
508+
Most scalar data types should have a corresponding array type (that is,
509+
a standard varlena array type whose element type is the scalar type, and
510+
which is referenced by the <structfield>typarray</structfield> field of
511+
the scalar type's <structname>pg_type</structname>
512+
entry). <filename>genbki.pl</filename> is able to generate
513+
the <structname>pg_type</structname> entry for the array type
514+
automatically in most cases.
515+
</para>
516+
517+
<para>
518+
To use this facility, just write an <literal>array_type_oid
519+
=&gt; <replaceable>nnnn</replaceable></literal> metadata field in the
520+
scalar type's <structname>pg_type</structname> entry, specifying the OID
521+
to use for the array type. You may then omit
522+
the <structfield>typarray</structfield> field, since it will be filled
523+
automatically with that OID.
524+
</para>
525+
526+
<para>
527+
The generated array type's name is the scalar type's name with an
528+
underscore prepended. The array entry's other fields are filled from
529+
<literal>BKI_ARRAY_DEFAULT(<replaceable>value</replaceable>)</literal>
530+
annotations in <filename>pg_type.h</filename>, or if there isn't one,
531+
copied from the scalar type. (There's also a special case
532+
for <structfield>typalign</structfield>.) Then
533+
the <structfield>typelem</structfield>
534+
and <structfield>typarray</structfield> fields of the two entries are
535+
set to cross-reference each other.
536+
</para>
537+
</sect2>
538+
501539
<sect2 id="system-catalog-recipes">
502540
<title>Recipes for Editing Data Files</title>
503541

‎src/backend/catalog/Catalog.pm

Lines changed: 74 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -191,6 +191,11 @@ sub ParseHeader
191191
{
192192
$column{default} = $1;
193193
}
194+
elsif (
195+
$attopt =~ /BKI_ARRAY_DEFAULT\(['"]?([^'"]+)['"]?\)/)
196+
{
197+
$column{array_default} = $1;
198+
}
194199
elsif ($attopt =~ /BKI_LOOKUP\((\w+)\)/)
195200
{
196201
$column{lookup} = $1;
@@ -277,19 +282,27 @@ sub ParseData
277282
}
278283
}
279284

280-
# If we found a hash reference, keep it.
281-
# Only keep non-data strings if we
282-
# are told to preserve formatting.
285+
# If we found a hash reference, keep it, unless it is marked as
286+
# autogenerated; in that case it'd duplicate an entry we'll
287+
# autogenerate below. (This makes it safe for reformat_dat_file.pl
288+
# with --full-tuples to print autogenerated entries, which seems like
289+
# useful behavior for debugging.)
290+
#
291+
# Only keep non-data strings if we are told to preserve formatting.
283292
if (defined $hash_ref)
284293
{
285-
push @$data, $hash_ref;
294+
push @$data, $hash_ref if !$hash_ref->{autogenerated};
286295
}
287296
elsif ($preserve_formatting)
288297
{
289298
push @$data, $_;
290299
}
291300
}
292301
close $ifd;
302+
303+
# If this is pg_type, auto-generate array types too.
304+
GenerateArrayTypes($schema, $data) if $catname eq 'pg_type';
305+
293306
return $data;
294307
}
295308

@@ -343,6 +356,63 @@ sub AddDefaultValues
343356
}
344357
}
345358

359+
# If a pg_type entry has an array_type_oid metadata field,
360+
# auto-generate an entry for its array type.
361+
sub GenerateArrayTypes
362+
{
363+
my $pgtype_schema = shift;
364+
my $types = shift;
365+
my @array_types;
366+
367+
foreach my $elem_type (@$types)
368+
{
369+
next if !(ref $elem_type eq 'HASH');
370+
next if !defined($elem_type->{array_type_oid});
371+
372+
my %array_type;
373+
374+
# Set up metadata fields for array type.
375+
$array_type{oid} = $elem_type->{array_type_oid};
376+
$array_type{autogenerated} = 1;
377+
$array_type{line_number} = $elem_type->{line_number};
378+
379+
# Set up column values derived from the element type.
380+
$array_type{typname} = '_' . $elem_type->{typname};
381+
$array_type{typelem} = $elem_type->{typname};
382+
383+
# Arrays require INT alignment, unless the element type requires
384+
# DOUBLE alignment.
385+
$array_type{typalign} = $elem_type->{typalign} eq 'd' ? 'd' : 'i';
386+
387+
# Fill in the rest of the array entry's fields.
388+
foreach my $column (@$pgtype_schema)
389+
{
390+
my $attname = $column->{name};
391+
392+
# Skip if we already set it above.
393+
next if defined $array_type{$attname};
394+
395+
# Apply the BKI_ARRAY_DEFAULT setting if there is one,
396+
# otherwise copy the field from the element type.
397+
if (defined $column->{array_default})
398+
{
399+
$array_type{$attname} = $column->{array_default};
400+
}
401+
else
402+
{
403+
$array_type{$attname} = $elem_type->{$attname};
404+
}
405+
}
406+
407+
# Lastly, cross-link the array to the element type.
408+
$elem_type->{typarray} = $array_type{typname};
409+
410+
push @array_types, \%array_type;
411+
}
412+
413+
push @$types, @array_types;
414+
}
415+
346416
# Rename temporary files to final names.
347417
# Call this function with the final file name and the .tmp extension.
348418
#

‎src/backend/catalog/genbki.pl

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -394,7 +394,9 @@
394394
next
395395
if $key eq "oid"
396396
|| $key eq "oid_symbol"
397+
|| $key eq "array_type_oid"
397398
|| $key eq "descr"
399+
|| $key eq "autogenerated"
398400
|| $key eq "line_number";
399401
die sprintf "unrecognized field name \"%s\" in %s.dat line %s\n",
400402
$key, $catname, $bki_values{line_number}

‎src/include/catalog/genbki.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -34,6 +34,8 @@
3434
#define BKI_FORCE_NOT_NULL
3535
/* Specifies a default value for a catalog field */
3636
#define BKI_DEFAULT(value)
37+
/* Specifies a default value for auto-generated array types */
38+
#define BKI_ARRAY_DEFAULT(value)
3739
/* Indicates how to perform name lookups for an OID or OID-array field */
3840
#define BKI_LOOKUP(catalog)
3941

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