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Create a new type category for "internal use" types. 

Historically we've put type "char" into the S (String) typcategory,
although calling it a string is a stretch considering it can only
store one byte.  (In our actual usage, it's more like an enum.)
This choice now seems wrong in view of the special heuristics
that parse_func.c and parse_coerce.c have for TYPCATEGORY_STRING:
it's not a great idea for "char" to have those preferential casting
behaviors.

Worse than that, recent patches inventing special-purpose types
like pg_node_tree have assigned typcategory S to those types,
meaning they also get preferential casting treatment that's designed
on the assumption that they can hold arbitrary text.

To fix, invent a new category TYPCATEGORY_INTERNAL for internal-use
types, and assign that to all these types.  I used code 'Z' for
lack of a better idea ('I' was already taken).

This change breaks one query in psql/describe.c, which now needs to
explicitly cast a catalog "char" column to text before concatenating
it with an undecorated literal.  Also, a test case in contrib/citext
now needs an explicit cast to convert citext to "char".  Since the
point of this change is to not have "char" be a surprisingly-available
cast target, these breakages seem OK.

Per report from Ian Campbell.

Discussion: https://postgr.es/m/2216388.1638480141@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2021-12-11 14:10:51 -05:00
parent fe60b67250
commit 07eee5a0dc
8 changed files with 29 additions and 13 deletions
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7
contrib/citext/expected/citext.out
View File

@ -1089,7 +1089,12 @@ INSERT INTO caster (char) VALUES ('f'::citext);
INSERT INTO caster (citext) VALUES ('f'::char);
INSERT INTO caster (chr) VALUES ('f'::text);
INSERT INTO caster (text) VALUES ('f'::"char");
INSERT INTO caster (chr) VALUES ('f'::citext);
INSERT INTO caster (chr) VALUES ('f'::citext); -- requires cast
ERROR: column "chr" is of type "char" but expression is of type citext
LINE 1: INSERT INTO caster (chr) VALUES ('f'::citext);
^
HINT: You will need to rewrite or cast the expression.
INSERT INTO caster (chr) VALUES ('f'::citext::text);
INSERT INTO caster (citext) VALUES ('f'::"char");
INSERT INTO caster (name) VALUES ('foo'::text);
INSERT INTO caster (text) VALUES ('foo'::name);

7
contrib/citext/expected/citext_1.out
View File

@ -1089,7 +1089,12 @@ INSERT INTO caster (char) VALUES ('f'::citext);
INSERT INTO caster (citext) VALUES ('f'::char);
INSERT INTO caster (chr) VALUES ('f'::text);
INSERT INTO caster (text) VALUES ('f'::"char");
INSERT INTO caster (chr) VALUES ('f'::citext);
INSERT INTO caster (chr) VALUES ('f'::citext); -- requires cast
ERROR: column "chr" is of type "char" but expression is of type citext
LINE 1: INSERT INTO caster (chr) VALUES ('f'::citext);
^
HINT: You will need to rewrite or cast the expression.
INSERT INTO caster (chr) VALUES ('f'::citext::text);
INSERT INTO caster (citext) VALUES ('f'::"char");
INSERT INTO caster (name) VALUES ('foo'::text);
INSERT INTO caster (text) VALUES ('foo'::name);

3
contrib/citext/sql/citext.sql
View File

@ -361,7 +361,8 @@ INSERT INTO caster (citext) VALUES ('f'::char);
INSERT INTO caster (chr) VALUES ('f'::text);
INSERT INTO caster (text) VALUES ('f'::"char");
INSERT INTO caster (chr) VALUES ('f'::citext);
INSERT INTO caster (chr) VALUES ('f'::citext); -- requires cast
INSERT INTO caster (chr) VALUES ('f'::citext::text);
INSERT INTO caster (citext) VALUES ('f'::"char");
INSERT INTO caster (name) VALUES ('foo'::text);

4
doc/src/sgml/catalogs.sgml
View File

@ -9317,6 +9317,10 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
<entry><literal>X</literal></entry>
<entry><type>unknown</type> type</entry>
</row>
<row>
<entry><literal>Z</literal></entry>
<entry>Internal-use types</entry>
</row>
</tbody>
</tgroup>
</table>

4
src/bin/psql/describe.c
View File

@ -1142,7 +1142,7 @@ permissionsList(const char *pattern)
",\n pg_catalog.array_to_string(ARRAY(\n"
" SELECT polname\n"
" || CASE WHEN polcmd != '*' THEN\n"
" E' (' || polcmd || E'):'\n"
" E' (' || polcmd::pg_catalog.text || E'):'\n"
" ELSE E':'\n"
" END\n"
" || CASE WHEN polqual IS NOT NULL THEN\n"
@ -1176,7 +1176,7 @@ permissionsList(const char *pattern)
" E' (RESTRICTIVE)'\n"
" ELSE '' END\n"
" || CASE WHEN polcmd != '*' THEN\n"
" E' (' || polcmd || E'):'\n"
" E' (' || polcmd::pg_catalog.text || E'):'\n"
" ELSE E':'\n"
" END\n"
" || CASE WHEN polqual IS NOT NULL THEN\n"

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202112081
#define CATALOG_VERSION_NO 202112111
#endif

14
src/include/catalog/pg_type.dat
View File

@ -42,7 +42,7 @@
typinput => 'byteain', typoutput => 'byteaout', typreceive => 'bytearecv',
typsend => 'byteasend', typalign => 'i', typstorage => 'x' },
{ oid => '18', array_type_oid => '1002', descr => 'single character',
typname => 'char', typlen => '1', typbyval => 't', typcategory => 'S',
typname => 'char', typlen => '1', typbyval => 't', typcategory => 'Z',
typinput => 'charin', typoutput => 'charout', typreceive => 'charrecv',
typsend => 'charsend', typalign => 'c' },
{ oid => '19', array_type_oid => '1003',
@ -145,24 +145,24 @@
typsend => 'xml_send', typalign => 'i', typstorage => 'x' },
{ oid => '194', descr => 'string representing an internal node tree',
typname => 'pg_node_tree', typlen => '-1', typbyval => 'f',
typcategory => 'S', typinput => 'pg_node_tree_in',
typcategory => 'Z', typinput => 'pg_node_tree_in',
typoutput => 'pg_node_tree_out', typreceive => 'pg_node_tree_recv',
typsend => 'pg_node_tree_send', typalign => 'i', typstorage => 'x',
typcollation => 'default' },
{ oid => '3361', descr => 'multivariate ndistinct coefficients',
typname => 'pg_ndistinct', typlen => '-1', typbyval => 'f',
typcategory => 'S', typinput => 'pg_ndistinct_in',
typcategory => 'Z', typinput => 'pg_ndistinct_in',
typoutput => 'pg_ndistinct_out', typreceive => 'pg_ndistinct_recv',
typsend => 'pg_ndistinct_send', typalign => 'i', typstorage => 'x',
typcollation => 'default' },
{ oid => '3402', descr => 'multivariate dependencies',
typname => 'pg_dependencies', typlen => '-1', typbyval => 'f',
typcategory => 'S', typinput => 'pg_dependencies_in',
typcategory => 'Z', typinput => 'pg_dependencies_in',
typoutput => 'pg_dependencies_out', typreceive => 'pg_dependencies_recv',
typsend => 'pg_dependencies_send', typalign => 'i', typstorage => 'x',
typcollation => 'default' },
{ oid => '5017', descr => 'multivariate MCV list',
typname => 'pg_mcv_list', typlen => '-1', typbyval => 'f', typcategory => 'S',
typname => 'pg_mcv_list', typlen => '-1', typbyval => 'f', typcategory => 'Z',
typinput => 'pg_mcv_list_in', typoutput => 'pg_mcv_list_out',
typreceive => 'pg_mcv_list_recv', typsend => 'pg_mcv_list_send',
typalign => 'i', typstorage => 'x', typcollation => 'default' },
@ -681,13 +681,13 @@
typalign => 'd', typstorage => 'x' },
{ oid => '4600', descr => 'BRIN bloom summary',
typname => 'pg_brin_bloom_summary', typlen => '-1', typbyval => 'f',
typcategory => 'S', typinput => 'brin_bloom_summary_in',
typcategory => 'Z', typinput => 'brin_bloom_summary_in',
typoutput => 'brin_bloom_summary_out',
typreceive => 'brin_bloom_summary_recv', typsend => 'brin_bloom_summary_send',
typalign => 'i', typstorage => 'x', typcollation => 'default' },
{ oid => '4601', descr => 'BRIN minmax-multi summary',
typname => 'pg_brin_minmax_multi_summary', typlen => '-1', typbyval => 'f',
typcategory => 'S', typinput => 'brin_minmax_multi_summary_in',
typcategory => 'Z', typinput => 'brin_minmax_multi_summary_in',
typoutput => 'brin_minmax_multi_summary_out',
typreceive => 'brin_minmax_multi_summary_recv',
typsend => 'brin_minmax_multi_summary_send', typalign => 'i',

1
src/include/catalog/pg_type.h
View File

@ -294,6 +294,7 @@ DECLARE_UNIQUE_INDEX(pg_type_typname_nsp_index, 2704, TypeNameNspIndexId, on pg_
#define TYPCATEGORY_USER 'U'
#define TYPCATEGORY_BITSTRING 'V' /* er ... "varbit"? */
#define TYPCATEGORY_UNKNOWN 'X'
#define TYPCATEGORY_INTERNAL 'Z'
#define TYPALIGN_CHAR 'c' /* char alignment (i.e. unaligned) */
#define TYPALIGN_SHORT 's' /* short alignment (typically 2 bytes) */