1 /*
2 ** 2003 April 6
3 **
4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
6 **
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This file contains code used to implement the VACUUM command.
13 **
14 ** Most of the code in this file may be omitted by defining the
15 ** SQLITE_OMIT_VACUUM macro.
16 **
17 ** $Id: vacuum.c,v 1.13.2.2 2004/06/04 19:07:54 drh Exp $
18 */
19 #include "sqliteInt.h"
20 #include "os.h"
21
22 /*
23 ** A structure for holding a dynamic string - a string that can grow
24 ** without bound.
25 */
26 typedef struct dynStr dynStr;
27 struct dynStr {
28 char *z; /* Text of the string in space obtained from sqliteMalloc() */
29 int nAlloc; /* Amount of space allocated to z[] */
30 int nUsed; /* Next unused slot in z[] */
31 };
32
33 /*
34 ** A structure that holds the vacuum context
35 */
36 typedef struct vacuumStruct vacuumStruct;
37 struct vacuumStruct {
38 sqlite *dbOld; /* Original database */
39 sqlite *dbNew; /* New database */
40 char **pzErrMsg; /* Write errors here */
41 int rc; /* Set to non-zero on an error */
42 const char *zTable; /* Name of a table being copied */
43 const char *zPragma; /* Pragma to execute with results */
44 dynStr s1, s2; /* Two dynamic strings */
45 };
46
47 #if !defined(SQLITE_OMIT_VACUUM) || SQLITE_OMIT_VACUUM
48 /*
49 ** Append text to a dynamic string
50 */
appendText(dynStr * p,const char * zText,int nText)51 static void appendText(dynStr *p, const char *zText, int nText){
52 if( nText<0 ) nText = strlen(zText);
53 if( p->z==0 || p->nUsed + nText + 1 >= p->nAlloc ){
54 char *zNew;
55 p->nAlloc = p->nUsed + nText + 1000;
56 zNew = sqliteRealloc(p->z, p->nAlloc);
57 if( zNew==0 ){
58 sqliteFree(p->z);
59 memset(p, 0, sizeof(*p));
60 return;
61 }
62 p->z = zNew;
63 }
64 memcpy(&p->z[p->nUsed], zText, nText+1);
65 p->nUsed += nText;
66 }
67
68 /*
69 ** Append text to a dynamic string, having first put the text in quotes.
70 */
appendQuoted(dynStr * p,const char * zText)71 static void appendQuoted(dynStr *p, const char *zText){
72 int i, j;
73 appendText(p, "'", 1);
74 for(i=j=0; zText[i]; i++){
75 if( zText[i]=='\'' ){
76 appendText(p, &zText[j], i-j+1);
77 j = i + 1;
78 appendText(p, "'", 1);
79 }
80 }
81 if( j<i ){
82 appendText(p, &zText[j], i-j);
83 }
84 appendText(p, "'", 1);
85 }
86
87 /*
88 ** Execute statements of SQL. If an error occurs, write the error
89 ** message into *pzErrMsg and return non-zero.
90 */
execsql(char ** pzErrMsg,sqlite * db,const char * zSql)91 static int execsql(char **pzErrMsg, sqlite *db, const char *zSql){
92 char *zErrMsg = 0;
93 int rc;
94
95 /* printf("***** executing *****\n%s\n", zSql); */
96 rc = sqlite_exec(db, zSql, 0, 0, &zErrMsg);
97 if( zErrMsg ){
98 sqliteSetString(pzErrMsg, zErrMsg, (char*)0);
99 sqlite_freemem(zErrMsg);
100 }
101 return rc;
102 }
103
104 /*
105 ** This is the second stage callback. Each invocation contains all the
106 ** data for a single row of a single table in the original database. This
107 ** routine must write that information into the new database.
108 */
vacuumCallback2(void * pArg,int argc,char ** argv,char ** NotUsed)109 static int vacuumCallback2(void *pArg, int argc, char **argv, char **NotUsed){
110 vacuumStruct *p = (vacuumStruct*)pArg;
111 const char *zSep = "(";
112 int i;
113
114 if( argv==0 ) return 0;
115 p->s2.nUsed = 0;
116 appendText(&p->s2, "INSERT INTO ", -1);
117 appendQuoted(&p->s2, p->zTable);
118 appendText(&p->s2, " VALUES", -1);
119 for(i=0; i<argc; i++){
120 appendText(&p->s2, zSep, 1);
121 zSep = ",";
122 if( argv[i]==0 ){
123 appendText(&p->s2, "NULL", 4);
124 }else{
125 appendQuoted(&p->s2, argv[i]);
126 }
127 }
128 appendText(&p->s2,")", 1);
129 p->rc = execsql(p->pzErrMsg, p->dbNew, p->s2.z);
130 return p->rc;
131 }
132
133 /*
134 ** This is the first stage callback. Each invocation contains three
135 ** arguments where are taken from the SQLITE_MASTER table of the original
136 ** database: (1) the entry type, (2) the entry name, and (3) the SQL for
137 ** the entry. In all cases, execute the SQL of the third argument.
138 ** For tables, run a query to select all entries in that table and
139 ** transfer them to the second-stage callback.
140 */
vacuumCallback1(void * pArg,int argc,char ** argv,char ** NotUsed)141 static int vacuumCallback1(void *pArg, int argc, char **argv, char **NotUsed){
142 vacuumStruct *p = (vacuumStruct*)pArg;
143 int rc = 0;
144 assert( argc==3 );
145 if( argv==0 ) return 0;
146 assert( argv[0]!=0 );
147 assert( argv[1]!=0 );
148 assert( argv[2]!=0 );
149 rc = execsql(p->pzErrMsg, p->dbNew, argv[2]);
150 if( rc==SQLITE_OK && strcmp(argv[0],"table")==0 ){
151 char *zErrMsg = 0;
152 p->s1.nUsed = 0;
153 appendText(&p->s1, "SELECT * FROM ", -1);
154 appendQuoted(&p->s1, argv[1]);
155 p->zTable = argv[1];
156 rc = sqlite_exec(p->dbOld, p->s1.z, vacuumCallback2, p, &zErrMsg);
157 if( zErrMsg ){
158 sqliteSetString(p->pzErrMsg, zErrMsg, (char*)0);
159 sqlite_freemem(zErrMsg);
160 }
161 }
162 if( rc!=SQLITE_ABORT ) p->rc = rc;
163 return rc;
164 }
165
166 /*
167 ** This callback is used to transfer PRAGMA settings from one database
168 ** to the other. The value in argv[0] should be passed to a pragma
169 ** identified by ((vacuumStruct*)pArg)->zPragma.
170 */
vacuumCallback3(void * pArg,int argc,char ** argv,char ** NotUsed)171 static int vacuumCallback3(void *pArg, int argc, char **argv, char **NotUsed){
172 vacuumStruct *p = (vacuumStruct*)pArg;
173 char zBuf[200];
174 assert( argc==1 );
175 if( argv==0 ) return 0;
176 assert( argv[0]!=0 );
177 assert( strlen(p->zPragma)<100 );
178 assert( strlen(argv[0])<30 );
179 sprintf(zBuf,"PRAGMA %s=%s;", p->zPragma, argv[0]);
180 p->rc = execsql(p->pzErrMsg, p->dbNew, zBuf);
181 return p->rc;
182 }
183
184 /*
185 ** Generate a random name of 20 character in length.
186 */
randomName(unsigned char * zBuf)187 static void randomName(unsigned char *zBuf){
188 static const unsigned char zChars[] =
189 "abcdefghijklmnopqrstuvwxyz"
190 "0123456789";
191 int i;
192 sqliteRandomness(20, zBuf);
193 for(i=0; i<20; i++){
194 zBuf[i] = zChars[ zBuf[i]%(sizeof(zChars)-1) ];
195 }
196 }
197 #endif
198
199 /*
200 ** The non-standard VACUUM command is used to clean up the database,
201 ** collapse free space, etc. It is modelled after the VACUUM command
202 ** in PostgreSQL.
203 **
204 ** In version 1.0.x of SQLite, the VACUUM command would call
205 ** gdbm_reorganize() on all the database tables. But beginning
206 ** with 2.0.0, SQLite no longer uses GDBM so this command has
207 ** become a no-op.
208 */
sqliteVacuum(Parse * pParse,Token * pTableName)209 void sqliteVacuum(Parse *pParse, Token *pTableName){
210 Vdbe *v = sqliteGetVdbe(pParse);
211 sqliteVdbeAddOp(v, OP_Vacuum, 0, 0);
212 return;
213 }
214
215 /*
216 ** This routine implements the OP_Vacuum opcode of the VDBE.
217 */
sqliteRunVacuum(char ** pzErrMsg,sqlite * db)218 int sqliteRunVacuum(char **pzErrMsg, sqlite *db){
219 #if !defined(SQLITE_OMIT_VACUUM) || SQLITE_OMIT_VACUUM
220 const char *zFilename; /* full pathname of the database file */
221 int nFilename; /* number of characters in zFilename[] */
222 char *zTemp = 0; /* a temporary file in same directory as zFilename */
223 sqlite *dbNew = 0; /* The new vacuumed database */
224 int rc = SQLITE_OK; /* Return code from service routines */
225 int i; /* Loop counter */
226 char *zErrMsg; /* Error message */
227 vacuumStruct sVac; /* Information passed to callbacks */
228
229 /* These are all of the pragmas that need to be transferred over
230 ** to the new database */
231 static const char *zPragma[] = {
232 "default_synchronous",
233 "default_cache_size",
234 /* "default_temp_store", */
235 };
236
237 if( db->flags & SQLITE_InTrans ){
238 sqliteSetString(pzErrMsg, "cannot VACUUM from within a transaction",
239 (char*)0);
240 return SQLITE_ERROR;
241 }
242 if( db->flags & SQLITE_Interrupt ){
243 return SQLITE_INTERRUPT;
244 }
245 memset(&sVac, 0, sizeof(sVac));
246
247 /* Get the full pathname of the database file and create two
248 ** temporary filenames in the same directory as the original file.
249 */
250 zFilename = sqliteBtreeGetFilename(db->aDb[0].pBt);
251 if( zFilename==0 ){
252 /* This only happens with the in-memory database. VACUUM is a no-op
253 ** there, so just return */
254 return SQLITE_OK;
255 }
256 nFilename = strlen(zFilename);
257 zTemp = sqliteMalloc( nFilename+100 );
258 if( zTemp==0 ) return SQLITE_NOMEM;
259 strcpy(zTemp, zFilename);
260 for(i=0; i<10; i++){
261 zTemp[nFilename] = '-';
262 randomName((unsigned char*)&zTemp[nFilename+1]);
263 if( !sqliteOsFileExists(zTemp) ) break;
264 }
265 if( i>=10 ){
266 sqliteSetString(pzErrMsg, "unable to create a temporary database file "
267 "in the same directory as the original database", (char*)0);
268 goto end_of_vacuum;
269 }
270
271
272 dbNew = sqlite_open(zTemp, 0, &zErrMsg);
273 if( dbNew==0 ){
274 sqliteSetString(pzErrMsg, "unable to open a temporary database at ",
275 zTemp, " - ", zErrMsg, (char*)0);
276 goto end_of_vacuum;
277 }
278 if( (rc = execsql(pzErrMsg, db, "BEGIN"))!=0 ) goto end_of_vacuum;
279 if( (rc = execsql(pzErrMsg, dbNew, "PRAGMA synchronous=off; BEGIN"))!=0 ){
280 goto end_of_vacuum;
281 }
282
283 sVac.dbOld = db;
284 sVac.dbNew = dbNew;
285 sVac.pzErrMsg = pzErrMsg;
286 for(i=0; rc==SQLITE_OK && i<sizeof(zPragma)/sizeof(zPragma[0]); i++){
287 char zBuf[200];
288 assert( strlen(zPragma[i])<100 );
289 sprintf(zBuf, "PRAGMA %s;", zPragma[i]);
290 sVac.zPragma = zPragma[i];
291 rc = sqlite_exec(db, zBuf, vacuumCallback3, &sVac, &zErrMsg);
292 }
293 if( rc==SQLITE_OK ){
294 rc = sqlite_exec(db,
295 "SELECT type, name, sql FROM sqlite_master "
296 "WHERE sql NOT NULL AND type!='view' "
297 "UNION ALL "
298 "SELECT type, name, sql FROM sqlite_master "
299 "WHERE sql NOT NULL AND type=='view'",
300 vacuumCallback1, &sVac, &zErrMsg);
301 }
302 if( rc==SQLITE_OK ){
303 rc = sqliteBtreeCopyFile(db->aDb[0].pBt, dbNew->aDb[0].pBt);
304 sqlite_exec(db, "COMMIT", 0, 0, 0);
305 sqliteResetInternalSchema(db, 0);
306 }
307
308 end_of_vacuum:
309 if( rc && zErrMsg!=0 ){
310 sqliteSetString(pzErrMsg, "unable to vacuum database - ",
311 zErrMsg, (char*)0);
312 }
313 sqlite_exec(db, "ROLLBACK", 0, 0, 0);
314 if( (dbNew && (dbNew->flags & SQLITE_Interrupt))
315 || (db->flags & SQLITE_Interrupt) ){
316 rc = SQLITE_INTERRUPT;
317 }
318 if( dbNew ) sqlite_close(dbNew);
319 sqliteOsDelete(zTemp);
320 sqliteFree(zTemp);
321 sqliteFree(sVac.s1.z);
322 sqliteFree(sVac.s2.z);
323 if( zErrMsg ) sqlite_freemem(zErrMsg);
324 if( rc==SQLITE_ABORT && sVac.rc!=SQLITE_INTERRUPT ) sVac.rc = SQLITE_ERROR;
325 return sVac.rc;
326 #endif
327 }
328