1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/persistentdata/persistentstorage/sql/SQLite364/vacuum.c Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,300 @@
1.4 +/*
1.5 +** 2003 April 6
1.6 +**
1.7 +** The author disclaims copyright to this source code. In place of
1.8 +** a legal notice, here is a blessing:
1.9 +**
1.10 +** May you do good and not evil.
1.11 +** May you find forgiveness for yourself and forgive others.
1.12 +** May you share freely, never taking more than you give.
1.13 +**
1.14 +*************************************************************************
1.15 +** This file contains code used to implement the VACUUM command.
1.16 +**
1.17 +** Most of the code in this file may be omitted by defining the
1.18 +** SQLITE_OMIT_VACUUM macro.
1.19 +**
1.20 +** $Id: vacuum.c,v 1.83 2008/08/26 21:07:27 drh Exp $
1.21 +*/
1.22 +#include "sqliteInt.h"
1.23 +#include "vdbeInt.h"
1.24 +
1.25 +#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
1.26 +/*
1.27 +** Execute zSql on database db. Return an error code.
1.28 +*/
1.29 +static int execSql(sqlite3 *db, const char *zSql){
1.30 + sqlite3_stmt *pStmt;
1.31 + if( !zSql ){
1.32 + return SQLITE_NOMEM;
1.33 + }
1.34 + if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
1.35 + return sqlite3_errcode(db);
1.36 + }
1.37 + while( SQLITE_ROW==sqlite3_step(pStmt) ){}
1.38 + return sqlite3_finalize(pStmt);
1.39 +}
1.40 +
1.41 +/*
1.42 +** Execute zSql on database db. The statement returns exactly
1.43 +** one column. Execute this as SQL on the same database.
1.44 +*/
1.45 +static int execExecSql(sqlite3 *db, const char *zSql){
1.46 + sqlite3_stmt *pStmt;
1.47 + int rc;
1.48 +
1.49 + rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
1.50 + if( rc!=SQLITE_OK ) return rc;
1.51 +
1.52 + while( SQLITE_ROW==sqlite3_step(pStmt) ){
1.53 + rc = execSql(db, (char*)sqlite3_column_text(pStmt, 0));
1.54 + if( rc!=SQLITE_OK ){
1.55 + sqlite3_finalize(pStmt);
1.56 + return rc;
1.57 + }
1.58 + }
1.59 +
1.60 + return sqlite3_finalize(pStmt);
1.61 +}
1.62 +
1.63 +/*
1.64 +** The non-standard VACUUM command is used to clean up the database,
1.65 +** collapse free space, etc. It is modelled after the VACUUM command
1.66 +** in PostgreSQL.
1.67 +**
1.68 +** In version 1.0.x of SQLite, the VACUUM command would call
1.69 +** gdbm_reorganize() on all the database tables. But beginning
1.70 +** with 2.0.0, SQLite no longer uses GDBM so this command has
1.71 +** become a no-op.
1.72 +*/
1.73 +void sqlite3Vacuum(Parse *pParse){
1.74 + Vdbe *v = sqlite3GetVdbe(pParse);
1.75 + if( v ){
1.76 + sqlite3VdbeAddOp2(v, OP_Vacuum, 0, 0);
1.77 + }
1.78 + return;
1.79 +}
1.80 +
1.81 +/*
1.82 +** This routine implements the OP_Vacuum opcode of the VDBE.
1.83 +*/
1.84 +int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
1.85 + int rc = SQLITE_OK; /* Return code from service routines */
1.86 + Btree *pMain; /* The database being vacuumed */
1.87 + Pager *pMainPager; /* Pager for database being vacuumed */
1.88 + Btree *pTemp; /* The temporary database we vacuum into */
1.89 + char *zSql = 0; /* SQL statements */
1.90 + int saved_flags; /* Saved value of the db->flags */
1.91 + int saved_nChange; /* Saved value of db->nChange */
1.92 + int saved_nTotalChange; /* Saved value of db->nTotalChange */
1.93 + Db *pDb = 0; /* Database to detach at end of vacuum */
1.94 + int isMemDb; /* True is vacuuming a :memory: database */
1.95 + int nRes;
1.96 +
1.97 + /* Save the current value of the write-schema flag before setting it. */
1.98 + saved_flags = db->flags;
1.99 + saved_nChange = db->nChange;
1.100 + saved_nTotalChange = db->nTotalChange;
1.101 + db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;
1.102 +
1.103 + if( !db->autoCommit ){
1.104 + sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction");
1.105 + rc = SQLITE_ERROR;
1.106 + goto end_of_vacuum;
1.107 + }
1.108 + pMain = db->aDb[0].pBt;
1.109 + pMainPager = sqlite3BtreePager(pMain);
1.110 + isMemDb = sqlite3PagerFile(pMainPager)->pMethods==0;
1.111 +
1.112 + /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
1.113 + ** can be set to 'off' for this file, as it is not recovered if a crash
1.114 + ** occurs anyway. The integrity of the database is maintained by a
1.115 + ** (possibly synchronous) transaction opened on the main database before
1.116 + ** sqlite3BtreeCopyFile() is called.
1.117 + **
1.118 + ** An optimisation would be to use a non-journaled pager.
1.119 + ** (Later:) I tried setting "PRAGMA vacuum_db.journal_mode=OFF" but
1.120 + ** that actually made the VACUUM run slower. Very little journalling
1.121 + ** actually occurs when doing a vacuum since the vacuum_db is initially
1.122 + ** empty. Only the journal header is written. Apparently it takes more
1.123 + ** time to parse and run the PRAGMA to turn journalling off than it does
1.124 + ** to write the journal header file.
1.125 + */
1.126 + zSql = "ATTACH '' AS vacuum_db;";
1.127 + rc = execSql(db, zSql);
1.128 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.129 + pDb = &db->aDb[db->nDb-1];
1.130 + assert( strcmp(db->aDb[db->nDb-1].zName,"vacuum_db")==0 );
1.131 + pTemp = db->aDb[db->nDb-1].pBt;
1.132 +
1.133 + nRes = sqlite3BtreeGetReserve(pMain);
1.134 +
1.135 + /* A VACUUM cannot change the pagesize of an encrypted database. */
1.136 +#ifdef SQLITE_HAS_CODEC
1.137 + if( db->nextPagesize ){
1.138 + extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
1.139 + int nKey;
1.140 + char *zKey;
1.141 + sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
1.142 + if( nKey ) db->nextPagesize = 0;
1.143 + }
1.144 +#endif
1.145 +
1.146 + if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes)
1.147 + || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes))
1.148 + || db->mallocFailed
1.149 + ){
1.150 + rc = SQLITE_NOMEM;
1.151 + goto end_of_vacuum;
1.152 + }
1.153 + rc = execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
1.154 + if( rc!=SQLITE_OK ){
1.155 + goto end_of_vacuum;
1.156 + }
1.157 +
1.158 +#ifndef SQLITE_OMIT_AUTOVACUUM
1.159 + sqlite3BtreeSetAutoVacuum(pTemp, db->nextAutovac>=0 ? db->nextAutovac :
1.160 + sqlite3BtreeGetAutoVacuum(pMain));
1.161 +#endif
1.162 +
1.163 + /* Begin a transaction */
1.164 + rc = execSql(db, "BEGIN EXCLUSIVE;");
1.165 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.166 +
1.167 + /* Query the schema of the main database. Create a mirror schema
1.168 + ** in the temporary database.
1.169 + */
1.170 + rc = execExecSql(db,
1.171 + "SELECT 'CREATE TABLE vacuum_db.' || substr(sql,14) "
1.172 + " FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
1.173 + " AND rootpage>0"
1.174 + );
1.175 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.176 + rc = execExecSql(db,
1.177 + "SELECT 'CREATE INDEX vacuum_db.' || substr(sql,14)"
1.178 + " FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %' ");
1.179 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.180 + rc = execExecSql(db,
1.181 + "SELECT 'CREATE UNIQUE INDEX vacuum_db.' || substr(sql,21) "
1.182 + " FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %'");
1.183 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.184 +
1.185 + /* Loop through the tables in the main database. For each, do
1.186 + ** an "INSERT INTO vacuum_db.xxx SELECT * FROM xxx;" to copy
1.187 + ** the contents to the temporary database.
1.188 + */
1.189 + rc = execExecSql(db,
1.190 + "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
1.191 + "|| ' SELECT * FROM ' || quote(name) || ';'"
1.192 + "FROM sqlite_master "
1.193 + "WHERE type = 'table' AND name!='sqlite_sequence' "
1.194 + " AND rootpage>0"
1.195 +
1.196 + );
1.197 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.198 +
1.199 + /* Copy over the sequence table
1.200 + */
1.201 + rc = execExecSql(db,
1.202 + "SELECT 'DELETE FROM vacuum_db.' || quote(name) || ';' "
1.203 + "FROM vacuum_db.sqlite_master WHERE name='sqlite_sequence' "
1.204 + );
1.205 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.206 + rc = execExecSql(db,
1.207 + "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
1.208 + "|| ' SELECT * FROM ' || quote(name) || ';' "
1.209 + "FROM vacuum_db.sqlite_master WHERE name=='sqlite_sequence';"
1.210 + );
1.211 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.212 +
1.213 +
1.214 + /* Copy the triggers, views, and virtual tables from the main database
1.215 + ** over to the temporary database. None of these objects has any
1.216 + ** associated storage, so all we have to do is copy their entries
1.217 + ** from the SQLITE_MASTER table.
1.218 + */
1.219 + rc = execSql(db,
1.220 + "INSERT INTO vacuum_db.sqlite_master "
1.221 + " SELECT type, name, tbl_name, rootpage, sql"
1.222 + " FROM sqlite_master"
1.223 + " WHERE type='view' OR type='trigger'"
1.224 + " OR (type='table' AND rootpage=0)"
1.225 + );
1.226 + if( rc ) goto end_of_vacuum;
1.227 +
1.228 + /* At this point, unless the main db was completely empty, there is now a
1.229 + ** transaction open on the vacuum database, but not on the main database.
1.230 + ** Open a btree level transaction on the main database. This allows a
1.231 + ** call to sqlite3BtreeCopyFile(). The main database btree level
1.232 + ** transaction is then committed, so the SQL level never knows it was
1.233 + ** opened for writing. This way, the SQL transaction used to create the
1.234 + ** temporary database never needs to be committed.
1.235 + */
1.236 + if( rc==SQLITE_OK ){
1.237 + u32 meta;
1.238 + int i;
1.239 +
1.240 + /* This array determines which meta meta values are preserved in the
1.241 + ** vacuum. Even entries are the meta value number and odd entries
1.242 + ** are an increment to apply to the meta value after the vacuum.
1.243 + ** The increment is used to increase the schema cookie so that other
1.244 + ** connections to the same database will know to reread the schema.
1.245 + */
1.246 + static const unsigned char aCopy[] = {
1.247 + 1, 1, /* Add one to the old schema cookie */
1.248 + 3, 0, /* Preserve the default page cache size */
1.249 + 5, 0, /* Preserve the default text encoding */
1.250 + 6, 0, /* Preserve the user version */
1.251 + };
1.252 +
1.253 + assert( 1==sqlite3BtreeIsInTrans(pTemp) );
1.254 + assert( 1==sqlite3BtreeIsInTrans(pMain) );
1.255 +
1.256 + /* Copy Btree meta values */
1.257 + for(i=0; i<sizeof(aCopy)/sizeof(aCopy[0]); i+=2){
1.258 + rc = sqlite3BtreeGetMeta(pMain, aCopy[i], &meta);
1.259 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.260 + rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]);
1.261 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.262 + }
1.263 +
1.264 + rc = sqlite3BtreeCopyFile(pMain, pTemp);
1.265 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.266 + rc = sqlite3BtreeCommit(pTemp);
1.267 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.268 +#ifndef SQLITE_OMIT_AUTOVACUUM
1.269 + sqlite3BtreeSetAutoVacuum(pMain, sqlite3BtreeGetAutoVacuum(pTemp));
1.270 +#endif
1.271 + rc = sqlite3BtreeCommit(pMain);
1.272 + }
1.273 +
1.274 + if( rc==SQLITE_OK ){
1.275 + rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes);
1.276 + }
1.277 +
1.278 +end_of_vacuum:
1.279 + /* Restore the original value of db->flags */
1.280 + db->flags = saved_flags;
1.281 + db->nChange = saved_nChange;
1.282 + db->nTotalChange = saved_nTotalChange;
1.283 +
1.284 + /* Currently there is an SQL level transaction open on the vacuum
1.285 + ** database. No locks are held on any other files (since the main file
1.286 + ** was committed at the btree level). So it safe to end the transaction
1.287 + ** by manually setting the autoCommit flag to true and detaching the
1.288 + ** vacuum database. The vacuum_db journal file is deleted when the pager
1.289 + ** is closed by the DETACH.
1.290 + */
1.291 + db->autoCommit = 1;
1.292 +
1.293 + if( pDb ){
1.294 + sqlite3BtreeClose(pDb->pBt);
1.295 + pDb->pBt = 0;
1.296 + pDb->pSchema = 0;
1.297 + }
1.298 +
1.299 + sqlite3ResetInternalSchema(db, 0);
1.300 +
1.301 + return rc;
1.302 +}
1.303 +#endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */