1 /*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 1998
5 * Sleepycat Software. All rights reserved.
6 */
7
8 #pragma ident "%Z%%M% %I% %E% SMI"
9
10 #include "config.h"
11
12 #ifndef lint
13 static const char sccsid[] = "@(#)db_join.c 10.10 (Sleepycat) 10/9/98";
14 #endif /* not lint */
15
16 #ifndef NO_SYSTEM_INCLUDES
17 #include <sys/types.h>
18
19 #include <errno.h>
20 #include <string.h>
21 #endif
22
23 #include "db_int.h"
24 #include "db_page.h"
25 #include "db_join.h"
26 #include "db_am.h"
27 #include "common_ext.h"
28
29 static int __db_join_close __P((DBC *));
30 static int __db_join_del __P((DBC *, u_int32_t));
31 static int __db_join_get __P((DBC *, DBT *, DBT *, u_int32_t));
32 static int __db_join_put __P((DBC *, DBT *, DBT *, u_int32_t));
33
34 /*
35 * This is the duplicate-assisted join functionality. Right now we're
36 * going to write it such that we return one item at a time, although
37 * I think we may need to optimize it to return them all at once.
38 * It should be easier to get it working this way, and I believe that
39 * changing it should be fairly straightforward.
40 *
41 * XXX
42 * Right now we do not maintain the number of duplicates so we do
43 * not optimize the join. If the caller does, then best performance
44 * will be achieved by putting the cursor with the smallest cardinality
45 * first.
46 *
47 * The first cursor moves sequentially through the duplicate set while
48 * the others search explicitly for the duplicate in question.
49 *
50 */
51
52 /*
53 * __db_join --
54 * This is the interface to the duplicate-assisted join functionality.
55 * In the same way that cursors mark a position in a database, a cursor
56 * can mark a position in a join. While most cursors are created by the
57 * cursor method of a DB, join cursors are created through an explicit
58 * call to DB->join.
59 *
60 * The curslist is an array of existing, intialized cursors and primary
61 * is the DB of the primary file. The data item that joins all the
62 * cursors in the curslist is used as the key into the primary and that
63 * key and data are returned. When no more items are left in the join
64 * set, the c_next operation off the join cursor will return DB_NOTFOUND.
65 *
66 * PUBLIC: int __db_join __P((DB *, DBC **, u_int32_t, DBC **));
67 */
68 int
__db_join(primary,curslist,flags,dbcp)69 __db_join(primary, curslist, flags, dbcp)
70 DB *primary;
71 DBC **curslist, **dbcp;
72 u_int32_t flags;
73 {
74 DBC *dbc;
75 JOIN_CURSOR *jc;
76 int i, ret;
77
78 DB_PANIC_CHECK(primary);
79
80 if ((ret = __db_joinchk(primary, flags)) != 0)
81 return (ret);
82
83 if (curslist == NULL || curslist[0] == NULL)
84 return (EINVAL);
85
86 dbc = NULL;
87 jc = NULL;
88
89 if ((ret = __os_calloc(1, sizeof(DBC), &dbc)) != 0)
90 goto err;
91
92 if ((ret = __os_calloc(1, sizeof(JOIN_CURSOR), &jc)) != 0)
93 goto err;
94
95 if ((ret = __os_malloc(256, NULL, &jc->j_key.data)) != 0)
96 goto err;
97 jc->j_key.ulen = 256;
98 F_SET(&jc->j_key, DB_DBT_USERMEM);
99
100 for (jc->j_curslist = curslist;
101 *jc->j_curslist != NULL; jc->j_curslist++)
102 ;
103 if ((ret = __os_calloc((jc->j_curslist - curslist + 1),
104 sizeof(DBC *), &jc->j_curslist)) != 0)
105 goto err;
106 for (i = 0; curslist[i] != NULL; i++) {
107 if (i != 0)
108 F_SET(curslist[i], DBC_KEYSET);
109 jc->j_curslist[i] = curslist[i];
110 }
111
112 dbc->c_close = __db_join_close;
113 dbc->c_del = __db_join_del;
114 dbc->c_get = __db_join_get;
115 dbc->c_put = __db_join_put;
116 dbc->internal = jc;
117 dbc->dbp = primary;
118 jc->j_init = 1;
119 jc->j_primary = primary;
120
121 *dbcp = dbc;
122
123 return (0);
124
125 err: if (jc != NULL) {
126 if (jc->j_curslist != NULL)
127 __os_free(jc->j_curslist,
128 (jc->j_curslist - curslist + 1) * sizeof(DBC *));
129 __os_free(jc, sizeof(JOIN_CURSOR));
130 }
131 if (dbc != NULL)
132 __os_free(dbc, sizeof(DBC));
133 return (ret);
134 }
135
136 static int
__db_join_put(dbc,key,data,flags)137 __db_join_put(dbc, key, data, flags)
138 DBC *dbc;
139 DBT *key;
140 DBT *data;
141 u_int32_t flags;
142 {
143 DB_PANIC_CHECK(dbc->dbp);
144
145 COMPQUIET(key, NULL);
146 COMPQUIET(data, NULL);
147 COMPQUIET(flags, 0);
148 return (EINVAL);
149 }
150
151 static int
__db_join_del(dbc,flags)152 __db_join_del(dbc, flags)
153 DBC *dbc;
154 u_int32_t flags;
155 {
156 DB_PANIC_CHECK(dbc->dbp);
157
158 COMPQUIET(flags, 0);
159 return (EINVAL);
160 }
161
162 static int
__db_join_get(dbc,key,data,flags)163 __db_join_get(dbc, key, data, flags)
164 DBC *dbc;
165 DBT *key, *data;
166 u_int32_t flags;
167 {
168 DB *dbp;
169 DBC **cpp;
170 JOIN_CURSOR *jc;
171 int ret;
172 u_int32_t operation;
173
174 dbp = dbc->dbp;
175
176 DB_PANIC_CHECK(dbp);
177
178 operation = LF_ISSET(DB_OPFLAGS_MASK);
179 if (operation != 0 && operation != DB_JOIN_ITEM)
180 return (__db_ferr(dbp->dbenv, "DBcursor->c_get", 0));
181
182 LF_CLR(DB_OPFLAGS_MASK);
183 if ((ret =
184 __db_fchk(dbp->dbenv, "DBcursor->c_get", flags, DB_RMW)) != 0)
185 return (ret);
186
187 jc = (JOIN_CURSOR *)dbc->internal;
188 retry:
189 ret = jc->j_curslist[0]->c_get(jc->j_curslist[0],
190 &jc->j_key, key, jc->j_init ? DB_CURRENT : DB_NEXT_DUP);
191
192 if (ret == ENOMEM) {
193 jc->j_key.ulen <<= 1;
194 if ((ret = __os_realloc(&jc->j_key.data, jc->j_key.ulen)) != 0)
195 return (ret);
196 goto retry;
197 }
198 if (ret != 0)
199 return (ret);
200
201 jc->j_init = 0;
202 do {
203 /*
204 * We have the first element; now look for it in the
205 * other cursors.
206 */
207 for (cpp = jc->j_curslist + 1; *cpp != NULL; cpp++) {
208 retry2: if ((ret = ((*cpp)->c_get)(*cpp,
209 &jc->j_key, key, DB_GET_BOTH)) == DB_NOTFOUND)
210 break;
211 if (ret == ENOMEM) {
212 jc->j_key.ulen <<= 1;
213 if ((ret = __os_realloc(&jc->j_key.data,
214 jc->j_key.ulen)) != 0)
215 return (ret);
216 goto retry2;
217 }
218 if (F_ISSET(*cpp, DBC_KEYSET)) {
219 F_CLR(*cpp, DBC_KEYSET);
220 F_SET(*cpp, DBC_CONTINUE);
221 }
222 }
223
224 /*
225 * If we got out of here with ret != 0, then we failed to
226 * find the duplicate in one of the files, so we go on to
227 * the next item in the outermost relation. If ret was
228 * equal to 0, then we've got something to return.
229 */
230 if (ret == 0)
231 break;
232 } while ((ret = jc->j_curslist[0]->c_get(jc->j_curslist[0],
233 &jc->j_key, key, DB_NEXT_DUP)) == 0);
234
235 /*
236 * If ret != 0 here, we've exhausted the first file. Otherwise,
237 * key and data are set and we need to do the lookup on the
238 * primary.
239 */
240 if (ret != 0)
241 return (ret);
242
243 if (operation == DB_JOIN_ITEM)
244 return (0);
245 else
246 return ((jc->j_primary->get)(jc->j_primary,
247 jc->j_curslist[0]->txn, key, data, 0));
248 }
249
250 static int
__db_join_close(dbc)251 __db_join_close(dbc)
252 DBC *dbc;
253 {
254 JOIN_CURSOR *jc;
255 int i;
256
257 DB_PANIC_CHECK(dbc->dbp);
258
259 jc = (JOIN_CURSOR *)dbc->internal;
260
261 /*
262 * Clear the optimization flag in the cursors.
263 */
264 for (i = 0; jc->j_curslist[i] != NULL; i++)
265 F_CLR(jc->j_curslist[i], DBC_CONTINUE | DBC_KEYSET);
266
267 __os_free(jc->j_curslist, 0);
268 __os_free(jc->j_key.data, jc->j_key.ulen);
269 __os_free(jc, sizeof(JOIN_CURSOR));
270 __os_free(dbc, sizeof(DBC));
271
272 return (0);
273 }
274