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Commit8e68d78

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Allow the syntax CREATE TYPE foo, with no parameters, to permit explicit
creation of a shell type. This allows a less hacky way of dealing withthe mutual dependency between a datatype and its I/O functions: make ashell type, then make the functions, then define the datatype fully.We should fix pg_dump to handle things this way, but this commit just dealswith the backend.Martijn van Oosterhout, with some corrections by Tom Lane.
1 parent7f19339 commit8e68d78

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12 files changed

+220
-86
lines changed

12 files changed

+220
-86
lines changed

‎doc/src/sgml/ref/create_type.sgml

Lines changed: 37 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/create_type.sgml,v 1.60 2006/01/13 18:06:45 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/create_type.sgml,v 1.61 2006/02/28 22:37:25 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -37,6 +37,8 @@ CREATE TYPE <replaceable class="parameter">name</replaceable> (
3737
[ , ELEMENT = <replaceable class="parameter">element</replaceable> ]
3838
[ , DELIMITER = <replaceable class="parameter">delimiter</replaceable> ]
3939
)
40+
41+
CREATE TYPE <replaceable class="parameter">name</replaceable>
4042
</synopsis>
4143
</refsynopsisdiv>
4244

@@ -142,17 +144,16 @@ CREATE TYPE <replaceable class="parameter">name</replaceable> (
142144

143145
<para>
144146
You should at this point be wondering how the input and output functions
145-
can be declared to have results or arguments of the new type, when they have
146-
to be created before the new type can be created. The answer is that the
147-
input function must be created first, then the output function (and
148-
the binary I/O functions if wanted), and finally the data type.
149-
<productname>PostgreSQL</productname> will first see the name of the new
150-
data type as the return type of the input function. It will create a
151-
<quote>shell</> type, which is simply a placeholder entry in
152-
the system catalog, and link the input function definition to the shell
153-
type. Similarly the other functions will be linked to the (now already
154-
existing) shell type. Finally, <command>CREATE TYPE</> replaces the
155-
shell entry with a complete type definition, and the new type can be used.
147+
can be declared to have results or arguments of the new type, when they
148+
have to be created before the new type can be created. The answer is that
149+
the type should first be defined as a <firstterm>shell type</>, which is a
150+
placeholder type that has no properties except a name and an owner. This
151+
is done by issuing the command <literal>CREATE TYPE
152+
<replaceable>name</></literal>, with no additional parameters. Then the
153+
I/O functions can be defined referencing the shell type. Finally,
154+
<command>CREATE TYPE</> with a full definition replaces the shell entry
155+
with a complete, valid type definition, after which the new type can be
156+
used normally.
156157
</para>
157158

158159
<para>
@@ -457,17 +458,33 @@ CREATE TYPE <replaceable class="parameter">name</replaceable> (
457458
while converting it to or from external form.
458459
</para>
459460

461+
<para>
462+
Before <productname>PostgreSQL</productname> version 8.2, the syntax
463+
<literal>CREATE TYPE <replaceable>name</></literal> did not exist.
464+
The way to create a new base type was to create its input function first.
465+
In this approach, <productname>PostgreSQL</productname> will first see
466+
the name of the new data type as the return type of the input function.
467+
The shell type is implicitly created in this situation, and then it
468+
can be referenced in the definitions of the remaining I/O functions.
469+
This approach still works, but is deprecated and may be disallowed in
470+
some future release. Also, to avoid accidentally cluttering
471+
the catalogs with shell types as a result of simple typos in function
472+
definitions, a shell type will only be made this way when the input
473+
function is written in C.
474+
</para>
475+
460476
<para>
461477
In <productname>PostgreSQL</productname> versions before 7.3, it
462-
was customary to avoid creating a shell type by replacing the
478+
was customary to avoid creating a shell typeat all,by replacing the
463479
functions' forward references to the type name with the placeholder
464480
pseudotype <type>opaque</>. The <type>cstring</> arguments and
465481
results also had to be declared as <type>opaque</> before 7.3. To
466482
support loading of old dump files, <command>CREATE TYPE</> will
467-
accept functions declared using <type>opaque</>, but it will issue
468-
a notice and change the function's declaration to use the correct
483+
acceptI/Ofunctions declared using <type>opaque</>, but it will issue
484+
a notice and change the function declarations to use the correct
469485
types.
470486
</para>
487+
471488
</refsect1>
472489

473490
<refsect1>
@@ -489,6 +506,11 @@ $$ LANGUAGE SQL;
489506
This example creates the base data type <type>box</type> and then uses the
490507
type in a table definition:
491508
<programlisting>
509+
CREATE TYPE box;
510+
511+
CREATE FUNCTION my_box_in_function(cstring) RETURNS box AS ... ;
512+
CREATE FUNCTION my_box_out_function(box) RETURNS cstring AS ... ;
513+
492514
CREATE TYPE box (
493515
INTERNALLENGTH = 16,
494516
INPUT = my_box_in_function,

‎doc/src/sgml/xtypes.sgml

Lines changed: 12 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/xtypes.sgml,v 1.25 2005/01/10 00:04:38 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/xtypes.sgml,v 1.26 2006/02/28 22:37:25 tgl Exp $
33
-->
44

55
<sect1 id="xtypes">
@@ -168,8 +168,16 @@ complex_send(PG_FUNCTION_ARGS)
168168
</para>
169169

170170
<para>
171-
To define the <type>complex</type> type, we need to create the
172-
user-defined I/O functions before creating the type:
171+
Once we have written the I/O functions and compiled them into a shared
172+
library, we can define the <type>complex</type> type in SQL.
173+
First we declare it as a shell type:
174+
175+
<programlisting>
176+
CREATE TYPE complex;
177+
</programlisting>
178+
179+
This serves as a placeholder that allows us to reference the type while
180+
defining its I/O functions. Now we can define the I/O functions:
173181

174182
<programlisting>
175183
CREATE FUNCTION complex_in(cstring)
@@ -192,15 +200,10 @@ CREATE FUNCTION complex_send(complex)
192200
AS '<replaceable>filename</replaceable>'
193201
LANGUAGE C IMMUTABLE STRICT;
194202
</programlisting>
195-
196-
Notice that the declarations of the input and output functions must
197-
reference the not-yet-defined type. This is allowed, but will draw
198-
warning messages that may be ignored. The input function must
199-
appear first.
200203
</para>
201204

202205
<para>
203-
Finally, we candeclare the data type:
206+
Finally, we canprovide the full definition of the data type:
204207
<programlisting>
205208
CREATE TYPE complex (
206209
internallength = 16,

‎src/backend/catalog/pg_type.c

Lines changed: 43 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/catalog/pg_type.c,v 1.104 2005/10/15 02:49:14 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/catalog/pg_type.c,v 1.105 2006/02/28 22:37:25 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -20,23 +20,26 @@
2020
#include"catalog/pg_namespace.h"
2121
#include"catalog/pg_proc.h"
2222
#include"catalog/pg_type.h"
23+
#include"commands/typecmds.h"
2324
#include"miscadmin.h"
25+
#include"utils/acl.h"
2426
#include"utils/builtins.h"
27+
#include"utils/fmgroids.h"
2528
#include"utils/lsyscache.h"
2629
#include"utils/syscache.h"
2730

2831

2932
/* ----------------------------------------------------------------
3033
*TypeShellMake
3134
*
32-
*This procedure inserts a "shell" tuple into thetype
33-
*relation.The type tuple inserted hasinvalidvalues
34-
*and in particular, the"typisdefined" field is false.
35+
*This procedure inserts a "shell" tuple into thepg_type relation.
36+
*The type tuple inserted hasvalid but dummyvalues, and its
37+
*"typisdefined" field is false indicating it's not really defined.
3538
*
36-
*This is used so that a tuple exists in the catalogs.
37-
*The invalid fields should be fixed up sometime after
38-
*this routineiscalled, and then the "typeisdefined"
39-
*field isset to true. -cim 6/15/90
39+
*This is used so that a tuple exists in the catalogs. The I/O
40+
*functions for the type will link to this tuple. When the full
41+
*CREATE TYPE commandisissued, the bogus values will be replaced
42+
*with correct ones, and "typisdefined" will beset to true.
4043
* ----------------------------------------------------------------
4144
*/
4245
Oid
@@ -70,30 +73,35 @@ TypeShellMake(const char *typeName, Oid typeNamespace)
7073

7174
/*
7275
* initialize *values with the type name and dummy values
76+
*
77+
* The representational details are the same as int4 ... it doesn't
78+
* really matter what they are so long as they are consistent. Also
79+
* note that we give it typtype = 'p' (pseudotype) as extra insurance
80+
* that it won't be mistaken for a usable type.
7381
*/
7482
i=0;
7583
namestrcpy(&name,typeName);
7684
values[i++]=NameGetDatum(&name);/* typname */
7785
values[i++]=ObjectIdGetDatum(typeNamespace);/* typnamespace */
7886
values[i++]=ObjectIdGetDatum(GetUserId());/* typowner */
79-
values[i++]=Int16GetDatum(0);/* typlen */
80-
values[i++]=BoolGetDatum(false);/* typbyval */
81-
values[i++]=CharGetDatum(0);/* typtype */
82-
values[i++]=BoolGetDatum(false);/* typisdefined */
83-
values[i++]=CharGetDatum(0);/* typdelim */
84-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typrelid */
85-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typelem */
86-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typinput */
87-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typoutput */
88-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typreceive */
89-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typsend */
90-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typanalyze */
91-
values[i++]=CharGetDatum('i');/* typalign */
92-
values[i++]=CharGetDatum('p');/* typstorage */
93-
values[i++]=BoolGetDatum(false);/* typnotnull */
94-
values[i++]=ObjectIdGetDatum(InvalidOid);/* typbasetype */
95-
values[i++]=Int32GetDatum(-1);/* typtypmod */
96-
values[i++]=Int32GetDatum(0);/* typndims */
87+
values[i++]=Int16GetDatum(sizeof(int4));/* typlen */
88+
values[i++]=BoolGetDatum(true);/* typbyval */
89+
values[i++]=CharGetDatum('p');/* typtype */
90+
values[i++]=BoolGetDatum(false);/* typisdefined */
91+
values[i++]=CharGetDatum(DEFAULT_TYPDELIM);/* typdelim */
92+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typrelid */
93+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typelem */
94+
values[i++]=ObjectIdGetDatum(F_SHELL_IN);/* typinput */
95+
values[i++]=ObjectIdGetDatum(F_SHELL_OUT);/* typoutput */
96+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typreceive */
97+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typsend */
98+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typanalyze */
99+
values[i++]=CharGetDatum('i');/* typalign */
100+
values[i++]=CharGetDatum('p');/* typstorage */
101+
values[i++]=BoolGetDatum(false);/* typnotnull */
102+
values[i++]=ObjectIdGetDatum(InvalidOid);/* typbasetype */
103+
values[i++]=Int32GetDatum(-1);/* typtypmod */
104+
values[i++]=Int32GetDatum(0);/* typndims */
97105
nulls[i++]='n';/* typdefaultbin */
98106
nulls[i++]='n';/* typdefault */
99107

@@ -118,8 +126,8 @@ TypeShellMake(const char *typeName, Oid typeNamespace)
118126
InvalidOid,
119127
0,
120128
GetUserId(),
121-
InvalidOid,
122-
InvalidOid,
129+
F_SHELL_IN,
130+
F_SHELL_OUT,
123131
InvalidOid,
124132
InvalidOid,
125133
InvalidOid,
@@ -289,7 +297,13 @@ TypeCreate(const char *typeName,
289297
errmsg("type \"%s\" already exists",typeName)));
290298

291299
/*
292-
* Okay to update existing "shell" type tuple
300+
* shell type must have been created by same owner
301+
*/
302+
if (((Form_pg_type)GETSTRUCT(tup))->typowner!=GetUserId())
303+
aclcheck_error(ACLCHECK_NOT_OWNER,ACL_KIND_TYPE,typeName);
304+
305+
/*
306+
* Okay to update existing shell type tuple
293307
*/
294308
tup=heap_modifytuple(tup,
295309
RelationGetDescr(pg_type_desc),
@@ -350,8 +364,6 @@ TypeCreate(const char *typeName,
350364
* If rebuild is true, we remove existing dependencies and rebuild them
351365
* from scratch. This is needed for ALTER TYPE, and also when replacing
352366
* a shell type.
353-
*
354-
* NOTE: a shell type will have a dependency to its namespace, and no others.
355367
*/
356368
void
357369
GenerateTypeDependencies(OidtypeNamespace,

‎src/backend/commands/typecmds.c

Lines changed: 32 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.86 2006/01/13 18:06:45 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.87 2006/02/28 22:37:26 tgl Exp $
1212
*
1313
* DESCRIPTION
1414
* The "DefineFoo" routines take the parse tree and pick out the
@@ -138,6 +138,37 @@ DefineType(List *names, List *parameters)
138138
errmsg("type names must be %d characters or less",
139139
NAMEDATALEN-2)));
140140

141+
/*
142+
* Look to see if type already exists (presumably as a shell; if not,
143+
* TypeCreate will complain). If it doesn't, create it as a shell, so
144+
* that the OID is known for use in the I/O function definitions.
145+
*/
146+
typoid=GetSysCacheOid(TYPENAMENSP,
147+
CStringGetDatum(typeName),
148+
ObjectIdGetDatum(typeNamespace),
149+
0,0);
150+
if (!OidIsValid(typoid))
151+
{
152+
typoid=TypeShellMake(typeName,typeNamespace);
153+
/* Make new shell type visible for modification below */
154+
CommandCounterIncrement();
155+
156+
/*
157+
* If the command was a parameterless CREATE TYPE, we're done ---
158+
* creating the shell type was all we're supposed to do.
159+
*/
160+
if (parameters==NIL)
161+
return;
162+
}
163+
else
164+
{
165+
/* Complain if dummy CREATE TYPE and entry already exists */
166+
if (parameters==NIL)
167+
ereport(ERROR,
168+
(errcode(ERRCODE_DUPLICATE_OBJECT),
169+
errmsg("type \"%s\" already exists",typeName)));
170+
}
171+
141172
foreach(pl,parameters)
142173
{
143174
DefElem*defel= (DefElem*)lfirst(pl);
@@ -240,22 +271,6 @@ DefineType(List *names, List *parameters)
240271
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
241272
errmsg("type output function must be specified")));
242273

243-
/*
244-
* Look to see if type already exists (presumably as a shell; if not,
245-
* TypeCreate will complain). If it doesn't, create it as a shell, so
246-
* that the OID is known for use in the I/O function definitions.
247-
*/
248-
typoid=GetSysCacheOid(TYPENAMENSP,
249-
CStringGetDatum(typeName),
250-
ObjectIdGetDatum(typeNamespace),
251-
0,0);
252-
if (!OidIsValid(typoid))
253-
{
254-
typoid=TypeShellMake(typeName,typeNamespace);
255-
/* Make new shell type visible for modification below */
256-
CommandCounterIncrement();
257-
}
258-
259274
/*
260275
* Convert I/O proc names to OIDs
261276
*/

‎src/backend/parser/gram.y

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.530 2006/02/19 00:04:27 neilc Exp $
14+
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.531 2006/02/28 22:37:26 tgl Exp $
1515
*
1616
* HISTORY
1717
* AUTHORDATEMAJOR EVENT
@@ -2690,6 +2690,15 @@ DefineStmt:
26902690
n->definition =$4;
26912691
$$ = (Node *)n;
26922692
}
2693+
|CREATETYPE_Pany_name
2694+
{
2695+
/* Shell type (identified by lack of definition)*/
2696+
DefineStmt *n = makeNode(DefineStmt);
2697+
n->kind = OBJECT_TYPE;
2698+
n->defnames =$3;
2699+
n->definition = NIL;
2700+
$$ = (Node *)n;
2701+
}
26932702
|CREATETYPE_Pany_nameAS'('TableFuncElementList')'
26942703
{
26952704
CompositeTypeStmt *n = makeNode(CompositeTypeStmt);

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