Add regdatabase.

XXX: NEEDS CATVERSION BUMP

Author: Ian Lawrence Barwick <barwick@gmail.com>
Reviewed-by: Greg Sabino Mullane <htamfids@gmail.com>
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/aBpjJhyHpM2LYcG0%40nathan

Author: nathan-bossart

contrib/postgres_fdw/deparse.c

@@ -39,6 +39,7 @@
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_database.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_opfamily.h"
@@ -455,6 +456,11 @@ foreign_expr_walker(Node *node,
 											  AuthIdRelationId, fpinfo))
 								return false;
 							break;
+						case REGDATABASEOID:
+							if (!is_shippable(DatumGetObjectId(c->constvalue),
+											  DatabaseRelationId, fpinfo))
+								return false;
+							break;
 					}
 				}
 

doc/src/sgml/datatype.sgml

@@ -4737,6 +4737,10 @@ INSERT INTO mytable VALUES(-1);  -- fails
     <primary>regconfig</primary>
    </indexterm>
 
+   <indexterm zone="datatype-oid">
+    <primary>regdatabase</primary>
+   </indexterm>
+
    <indexterm zone="datatype-oid">
     <primary>regdictionary</primary>
    </indexterm>
@@ -4878,6 +4882,13 @@ SELECT * FROM pg_attribute
         <entry><literal>english</literal></entry>
        </row>
 
+       <row>
+        <entry><type>regdatabase</type></entry>
+        <entry><structname>pg_database</structname></entry>
+        <entry>database name</entry>
+        <entry><literal>template1</literal></entry>
+       </row>
+
        <row>
         <entry><type>regdictionary</type></entry>
         <entry><structname>pg_ts_dict</structname></entry>
@@ -5049,8 +5060,8 @@ WHERE ...
     be dropped without first removing the default expression.  The
     alternative of <literal>nextval('my_seq'::text)</literal> does not
     create a dependency.
-    (<type>regrole</type> is an exception to this property. Constants of this
-    type are not allowed in stored expressions.)
+    (<type>regdatabase</type> and <type>regrole</type> are exceptions to this
+    property.  Constants of these types are not allowed in stored expressions.)
    </para>
 
    <para>

doc/src/sgml/func.sgml

@@ -26757,6 +26757,23 @@ SELECT currval(pg_get_serial_sequence('sometable', 'id'));
        </para></entry>
       </row>
 
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>to_regdatabase</primary>
+        </indexterm>
+        <function>to_regdatabase</function> ( <type>text</type> )
+        <returnvalue>regdatabase</returnvalue>
+       </para>
+       <para>
+        Translates a textual database name to its OID.  A similar result is
+        obtained by casting the string to type <type>regdatabase</type> (see
+        <xref linkend="datatype-oid"/>); however, this function will return
+        <literal>NULL</literal> rather than throwing an error if the name is
+        not found.
+       </para></entry>
+      </row>
+
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>

doc/src/sgml/ref/pgupgrade.sgml

@@ -1110,7 +1110,8 @@ psql --username=postgres --file=script.sql postgres
     <member><type>regproc</type></member>
     <member><type>regprocedure</type></member>
    </simplelist>
-   (<type>regclass</type>, <type>regrole</type>, and <type>regtype</type> can be upgraded.)
+   (<type>regclass</type>, <type>regdatabase</type>, <type>regrole</type>, and
+   <type>regtype</type> can be upgraded.)
   </para>
 
   <para>

src/backend/bootstrap/bootstrap.c

@@ -109,6 +109,8 @@ static const struct typinfo TypInfo[] = {
 	F_REGROLEIN, F_REGROLEOUT},
 	{"regnamespace", REGNAMESPACEOID, 0, 4, true, TYPALIGN_INT, TYPSTORAGE_PLAIN, InvalidOid,
 	F_REGNAMESPACEIN, F_REGNAMESPACEOUT},
+	{"regdatabase", REGDATABASEOID, 0, 4, true, TYPALIGN_INT, TYPSTORAGE_PLAIN, InvalidOid,
+	F_REGDATABASEIN, F_REGDATABASEOUT},
 	{"text", TEXTOID, 0, -1, false, TYPALIGN_INT, TYPSTORAGE_EXTENDED, DEFAULT_COLLATION_OID,
 	F_TEXTIN, F_TEXTOUT},
 	{"oid", OIDOID, 0, 4, true, TYPALIGN_INT, TYPSTORAGE_PLAIN, InvalidOid,

src/backend/catalog/dependency.c

@@ -1850,6 +1850,17 @@ find_expr_references_walker(Node *node,
 							 errmsg("constant of the type %s cannot be used here",
 									"regrole")));
 					break;
+
+					/*
+					 * Dependencies for regdatabase should be shared among all
+					 * databases, so explicitly inhibit to have dependencies.
+					 */
+				case REGDATABASEOID:
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("constant of the type %s cannot be used here",
+									"regdatabase")));
+					break;
 			}
 		}
 		return false;

src/backend/utils/adt/regproc.c

@@ -30,6 +30,7 @@
 #include "catalog/pg_ts_config.h"
 #include "catalog/pg_ts_dict.h"
 #include "catalog/pg_type.h"
+#include "commands/dbcommands.h"
 #include "lib/stringinfo.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
@@ -1763,6 +1764,123 @@ regnamespacesend(PG_FUNCTION_ARGS)
 	return oidsend(fcinfo);
 }
 
+/*
+ * regdatabasein - converts database name to database OID
+ *
+ * We also accept a numeric OID, for symmetry with the output routine.
+ *
+ * '-' signifies unknown (OID 0).  In all other cases, the input must
+ * match an existing pg_database entry.
+ */
+Datum
+regdatabasein(PG_FUNCTION_ARGS)
+{
+	char	   *db_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
+	Oid			result;
+	List	   *names;
+
+	/* Handle "-" or numeric OID */
+	if (parseDashOrOid(db_name_or_oid, &result, escontext))
+		PG_RETURN_OID(result);
+
+	/* The rest of this wouldn't work in bootstrap mode */
+	if (IsBootstrapProcessingMode())
+		elog(ERROR, "regdatabase values must be OIDs in bootstrap mode");
+
+	/* Normal case: see if the name matches any pg_database entry. */
+	names = stringToQualifiedNameList(db_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
+
+	if (list_length(names) != 1)
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_INVALID_NAME),
+				 errmsg("invalid name syntax")));
+
+	result = get_database_oid(strVal(linitial(names)), true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("database \"%s\" does not exist",
+						strVal(linitial(names)))));
+
+	PG_RETURN_OID(result);
+}
+
+/*
+ * to_regdatabase - converts database name to database OID
+ *
+ * If the name is not found, we return NULL.
+ */
+Datum
+to_regdatabase(PG_FUNCTION_ARGS)
+{
+	char	   *db_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	Datum		result;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
+
+	if (!DirectInputFunctionCallSafe(regdatabasein, db_name,
+									 InvalidOid, -1,
+									 (Node *) &escontext,
+									 &result))
+		PG_RETURN_NULL();
+	PG_RETURN_DATUM(result);
+}
+
+/*
+ * regdatabaseout - converts database OID to database name
+ */
+Datum
+regdatabaseout(PG_FUNCTION_ARGS)
+{
+	Oid			dboid = PG_GETARG_OID(0);
+	char	   *result;
+
+	if (dboid == InvalidOid)
+	{
+		result = pstrdup("-");
+		PG_RETURN_CSTRING(result);
+	}
+
+	result = get_database_name(dboid);
+
+	if (result)
+	{
+		/* pstrdup is not really necessary, but it avoids a compiler warning */
+		result = pstrdup(quote_identifier(result));
+	}
+	else
+	{
+		/* If OID doesn't match any database, return it numerically */
+		result = (char *) palloc(NAMEDATALEN);
+		snprintf(result, NAMEDATALEN, "%u", dboid);
+	}
+
+	PG_RETURN_CSTRING(result);
+}
+
+/*
+ * regdatabaserecv - converts external binary format to regdatabase
+ */
+Datum
+regdatabaserecv(PG_FUNCTION_ARGS)
+{
+	/* Exactly the same as oidrecv, so share code */
+	return oidrecv(fcinfo);
+}
+
+/*
+ * regdatabasesend - converts regdatabase to binary format
+ */
+Datum
+regdatabasesend(PG_FUNCTION_ARGS)
+{
+	/* Exactly the same as oidsend, so share code */
+	return oidsend(fcinfo);
+}
+
 /*
  * text_regclass: convert text to regclass
  *

src/backend/utils/adt/selfuncs.c

@@ -4620,6 +4620,7 @@ convert_to_scalar(Datum value, Oid valuetypid, Oid collid, double *scaledvalue,
 		case REGDICTIONARYOID:
 		case REGROLEOID:
 		case REGNAMESPACEOID:
+		case REGDATABASEOID:
 			*scaledvalue = convert_numeric_to_scalar(value, valuetypid,
 													 &failure);
 			*scaledlobound = convert_numeric_to_scalar(lobound, boundstypid,
@@ -4752,6 +4753,7 @@ convert_numeric_to_scalar(Datum value, Oid typid, bool *failure)
 		case REGDICTIONARYOID:
 		case REGROLEOID:
 		case REGNAMESPACEOID:
+		case REGDATABASEOID:
 			/* we can treat OIDs as integers... */
 			return (double) DatumGetObjectId(value);
 	}

src/backend/utils/cache/catcache.c

@@ -317,6 +317,7 @@ GetCCHashEqFuncs(Oid keytype, CCHashFN *hashfunc, RegProcedure *eqfunc, CCFastEq
 		case REGDICTIONARYOID:
 		case REGROLEOID:
 		case REGNAMESPACEOID:
+		case REGDATABASEOID:
 			*hashfunc = int4hashfast;
 			*fasteqfunc = int4eqfast;
 			*eqfunc = F_OIDEQ;

src/bin/pg_upgrade/check.c

@@ -168,6 +168,7 @@ static DataTypesUsageChecks data_types_usage_checks[] =
 		/* pg_class.oid is preserved, so 'regclass' is OK */
 		"           'regcollation', "
 		"           'regconfig', "
+		/* pg_database.oid is preserved, so 'regdatabase' is OK */
 		"           'regdictionary', "
 		"           'regnamespace', "
 		"           'regoper', "

src/include/catalog/pg_cast.dat

@@ -281,6 +281,20 @@
   castcontext => 'a', castmethod => 'f' },
 { castsource => 'regnamespace', casttarget => 'int4', castfunc => '0',
   castcontext => 'a', castmethod => 'b' },
+{ castsource => 'oid', casttarget => 'regdatabase', castfunc => '0',
+  castcontext => 'i', castmethod => 'b' },
+{ castsource => 'regdatabase', casttarget => 'oid', castfunc => '0',
+  castcontext => 'i', castmethod => 'b' },
+{ castsource => 'int8', casttarget => 'regdatabase', castfunc => 'oid',
+  castcontext => 'i', castmethod => 'f' },
+{ castsource => 'int2', casttarget => 'regdatabase', castfunc => 'int4(int2)',
+  castcontext => 'i', castmethod => 'f' },
+{ castsource => 'int4', casttarget => 'regdatabase', castfunc => '0',
+  castcontext => 'i', castmethod => 'b' },
+{ castsource => 'regdatabase', casttarget => 'int8', castfunc => 'int8(oid)',
+  castcontext => 'a', castmethod => 'f' },
+{ castsource => 'regdatabase', casttarget => 'int4', castfunc => '0',
+  castcontext => 'a', castmethod => 'b' },
 
 # String category
 { castsource => 'text', casttarget => 'bpchar', castfunc => '0',

src/include/catalog/pg_proc.dat

@@ -7454,6 +7454,17 @@
   prorettype => 'regnamespace', proargtypes => 'text',
   prosrc => 'to_regnamespace' },
 
+{ oid => '8321', descr => 'I/O',
+  proname => 'regdatabasein', provolatile => 's', prorettype => 'regdatabase',
+  proargtypes => 'cstring', prosrc => 'regdatabasein' },
+{ oid => '8322', descr => 'I/O',
+  proname => 'regdatabaseout', provolatile => 's', prorettype => 'cstring',
+  proargtypes => 'regdatabase', prosrc => 'regdatabaseout' },
+{ oid => '8323', descr => 'convert database name to regdatabase',
+  proname => 'to_regdatabase', provolatile => 's',
+  prorettype => 'regdatabase', proargtypes => 'text',
+  prosrc => 'to_regdatabase' },
+
 { oid => '6210', descr => 'test whether string is valid input for data type',
   proname => 'pg_input_is_valid', provolatile => 's', prorettype => 'bool',
   proargtypes => 'text text', prosrc => 'pg_input_is_valid' },
@@ -8312,6 +8323,12 @@
 { oid => '4088', descr => 'I/O',
   proname => 'regnamespacesend', prorettype => 'bytea',
   proargtypes => 'regnamespace', prosrc => 'regnamespacesend' },
+{ oid => '8324', descr => 'I/O',
+  proname => 'regdatabaserecv', prorettype => 'regdatabase',
+  proargtypes => 'internal', prosrc => 'regdatabaserecv' },
+{ oid => '8325', descr => 'I/O',
+  proname => 'regdatabasesend', prorettype => 'bytea',
+  proargtypes => 'regdatabase', prosrc => 'regdatabasesend' },
 { oid => '2456', descr => 'I/O',
   proname => 'bit_recv', prorettype => 'bit',
   proargtypes => 'internal oid int4', prosrc => 'bit_recv' },

src/include/catalog/pg_type.dat

@@ -399,6 +399,11 @@
   typinput => 'regnamespacein', typoutput => 'regnamespaceout',
   typreceive => 'regnamespacerecv', typsend => 'regnamespacesend',
   typalign => 'i' },
+{ oid => '8326', array_type_oid => '8327', descr => 'registered database',
+  typname => 'regdatabase', typlen => '4', typbyval => 't', typcategory => 'N',
+  typinput => 'regdatabasein', typoutput => 'regdatabaseout',
+  typreceive => 'regdatabaserecv', typsend => 'regdatabasesend',
+  typalign => 'i' },
 
 # uuid
 { oid => '2950', array_type_oid => '2951', descr => 'UUID',