1 /*-------------------------------------------------------------------------
2 *
3 * amcmds.c
4 * Routines for SQL commands that manipulate access methods.
5 *
6 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/commands/amcmds.c
12 *-------------------------------------------------------------------------
13 */
14 #include "postgres.h"
15
16 #include "access/htup_details.h"
17 #include "access/table.h"
18 #include "catalog/catalog.h"
19 #include "catalog/dependency.h"
20 #include "catalog/indexing.h"
21 #include "catalog/objectaccess.h"
22 #include "catalog/pg_am.h"
23 #include "catalog/pg_proc.h"
24 #include "catalog/pg_type.h"
25 #include "commands/defrem.h"
26 #include "miscadmin.h"
27 #include "parser/parse_func.h"
28 #include "utils/builtins.h"
29 #include "utils/lsyscache.h"
30 #include "utils/rel.h"
31 #include "utils/syscache.h"
32
33
34 static Oid lookup_am_handler_func(List *handler_name, char amtype);
35 static const char *get_am_type_string(char amtype);
36
37
38 /*
39 * CreateAccessMethod
40 * Registers a new access method.
41 */
42 ObjectAddress
CreateAccessMethod(CreateAmStmt * stmt)43 CreateAccessMethod(CreateAmStmt *stmt)
44 {
45 Relation rel;
46 ObjectAddress myself;
47 ObjectAddress referenced;
48 Oid amoid;
49 Oid amhandler;
50 bool nulls[Natts_pg_am];
51 Datum values[Natts_pg_am];
52 HeapTuple tup;
53
54 rel = table_open(AccessMethodRelationId, RowExclusiveLock);
55
56 /* Must be super user */
57 if (!superuser())
58 ereport(ERROR,
59 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
60 errmsg("permission denied to create access method \"%s\"",
61 stmt->amname),
62 errhint("Must be superuser to create an access method.")));
63
64 /* Check if name is used */
65 amoid = GetSysCacheOid1(AMNAME, Anum_pg_am_oid,
66 CStringGetDatum(stmt->amname));
67 if (OidIsValid(amoid))
68 {
69 ereport(ERROR,
70 (errcode(ERRCODE_DUPLICATE_OBJECT),
71 errmsg("access method \"%s\" already exists",
72 stmt->amname)));
73 }
74
75 /*
76 * Get the handler function oid, verifying the AM type while at it.
77 */
78 amhandler = lookup_am_handler_func(stmt->handler_name, stmt->amtype);
79
80 /*
81 * Insert tuple into pg_am.
82 */
83 memset(values, 0, sizeof(values));
84 memset(nulls, false, sizeof(nulls));
85
86 amoid = GetNewOidWithIndex(rel, AmOidIndexId, Anum_pg_am_oid);
87 values[Anum_pg_am_oid - 1] = ObjectIdGetDatum(amoid);
88 values[Anum_pg_am_amname - 1] =
89 DirectFunctionCall1(namein, CStringGetDatum(stmt->amname));
90 values[Anum_pg_am_amhandler - 1] = ObjectIdGetDatum(amhandler);
91 values[Anum_pg_am_amtype - 1] = CharGetDatum(stmt->amtype);
92
93 tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
94
95 CatalogTupleInsert(rel, tup);
96 heap_freetuple(tup);
97
98 myself.classId = AccessMethodRelationId;
99 myself.objectId = amoid;
100 myself.objectSubId = 0;
101
102 /* Record dependency on handler function */
103 referenced.classId = ProcedureRelationId;
104 referenced.objectId = amhandler;
105 referenced.objectSubId = 0;
106
107 recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
108
109 recordDependencyOnCurrentExtension(&myself, false);
110
111 InvokeObjectPostCreateHook(AccessMethodRelationId, amoid, 0);
112
113 table_close(rel, RowExclusiveLock);
114
115 return myself;
116 }
117
118 /*
119 * get_am_type_oid
120 * Worker for various get_am_*_oid variants
121 *
122 * If missing_ok is false, throw an error if access method not found. If
123 * true, just return InvalidOid.
124 *
125 * If amtype is not '\0', an error is raised if the AM found is not of the
126 * given type.
127 */
128 static Oid
get_am_type_oid(const char * amname,char amtype,bool missing_ok)129 get_am_type_oid(const char *amname, char amtype, bool missing_ok)
130 {
131 HeapTuple tup;
132 Oid oid = InvalidOid;
133
134 tup = SearchSysCache1(AMNAME, CStringGetDatum(amname));
135 if (HeapTupleIsValid(tup))
136 {
137 Form_pg_am amform = (Form_pg_am) GETSTRUCT(tup);
138
139 if (amtype != '\0' &&
140 amform->amtype != amtype)
141 ereport(ERROR,
142 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
143 errmsg("access method \"%s\" is not of type %s",
144 NameStr(amform->amname),
145 get_am_type_string(amtype))));
146
147 oid = amform->oid;
148 ReleaseSysCache(tup);
149 }
150
151 if (!OidIsValid(oid) && !missing_ok)
152 ereport(ERROR,
153 (errcode(ERRCODE_UNDEFINED_OBJECT),
154 errmsg("access method \"%s\" does not exist", amname)));
155 return oid;
156 }
157
158 /*
159 * get_index_am_oid - given an access method name, look up its OID
160 * and verify it corresponds to an index AM.
161 */
162 Oid
get_index_am_oid(const char * amname,bool missing_ok)163 get_index_am_oid(const char *amname, bool missing_ok)
164 {
165 return get_am_type_oid(amname, AMTYPE_INDEX, missing_ok);
166 }
167
168 /*
169 * get_table_am_oid - given an access method name, look up its OID
170 * and verify it corresponds to an table AM.
171 */
172 Oid
get_table_am_oid(const char * amname,bool missing_ok)173 get_table_am_oid(const char *amname, bool missing_ok)
174 {
175 return get_am_type_oid(amname, AMTYPE_TABLE, missing_ok);
176 }
177
178 /*
179 * get_am_oid - given an access method name, look up its OID.
180 * The type is not checked.
181 */
182 Oid
get_am_oid(const char * amname,bool missing_ok)183 get_am_oid(const char *amname, bool missing_ok)
184 {
185 return get_am_type_oid(amname, '\0', missing_ok);
186 }
187
188 /*
189 * get_am_name - given an access method OID, look up its name.
190 */
191 char *
get_am_name(Oid amOid)192 get_am_name(Oid amOid)
193 {
194 HeapTuple tup;
195 char *result = NULL;
196
197 tup = SearchSysCache1(AMOID, ObjectIdGetDatum(amOid));
198 if (HeapTupleIsValid(tup))
199 {
200 Form_pg_am amform = (Form_pg_am) GETSTRUCT(tup);
201
202 result = pstrdup(NameStr(amform->amname));
203 ReleaseSysCache(tup);
204 }
205 return result;
206 }
207
208 /*
209 * Convert single-character access method type into string for error reporting.
210 */
211 static const char *
get_am_type_string(char amtype)212 get_am_type_string(char amtype)
213 {
214 switch (amtype)
215 {
216 case AMTYPE_INDEX:
217 return "INDEX";
218 case AMTYPE_TABLE:
219 return "TABLE";
220 default:
221 /* shouldn't happen */
222 elog(ERROR, "invalid access method type '%c'", amtype);
223 return NULL; /* keep compiler quiet */
224 }
225 }
226
227 /*
228 * Convert a handler function name to an Oid. If the return type of the
229 * function doesn't match the given AM type, an error is raised.
230 *
231 * This function either return valid function Oid or throw an error.
232 */
233 static Oid
lookup_am_handler_func(List * handler_name,char amtype)234 lookup_am_handler_func(List *handler_name, char amtype)
235 {
236 Oid handlerOid;
237 Oid funcargtypes[1] = {INTERNALOID};
238 Oid expectedType = InvalidOid;
239
240 if (handler_name == NIL)
241 ereport(ERROR,
242 (errcode(ERRCODE_UNDEFINED_FUNCTION),
243 errmsg("handler function is not specified")));
244
245 /* handlers have one argument of type internal */
246 handlerOid = LookupFuncName(handler_name, 1, funcargtypes, false);
247
248 /* check that handler has the correct return type */
249 switch (amtype)
250 {
251 case AMTYPE_INDEX:
252 expectedType = INDEX_AM_HANDLEROID;
253 break;
254 case AMTYPE_TABLE:
255 expectedType = TABLE_AM_HANDLEROID;
256 break;
257 default:
258 elog(ERROR, "unrecognized access method type \"%c\"", amtype);
259 }
260
261 if (get_func_rettype(handlerOid) != expectedType)
262 ereport(ERROR,
263 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
264 errmsg("function %s must return type %s",
265 get_func_name(handlerOid),
266 format_type_extended(expectedType, -1, 0))));
267
268 return handlerOid;
269 }
270