| /* |
| ** 2003 April 6 |
| ** |
| ** The author disclaims copyright to this source code. In place of |
| ** a legal notice, here is a blessing: |
| ** |
| ** May you do good and not evil. |
| ** May you find forgiveness for yourself and forgive others. |
| ** May you share freely, never taking more than you give. |
| ** |
| ************************************************************************* |
| ** This file contains code used to implement the VACUUM command. |
| ** |
| ** Most of the code in this file may be omitted by defining the |
| ** SQLITE_OMIT_VACUUM macro. |
| */ |
| #include "sqliteInt.h" |
| #include "vdbeInt.h" |
| |
| #if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH) |
| /* |
| ** Finalize a prepared statement. If there was an error, store the |
| ** text of the error message in *pzErrMsg. Return the result code. |
| */ |
| static int vacuumFinalize(sqlite3 *db, sqlite3_stmt *pStmt, char **pzErrMsg){ |
| int rc; |
| rc = sqlite3VdbeFinalize((Vdbe*)pStmt); |
| if( rc ){ |
| sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db)); |
| } |
| return rc; |
| } |
| |
| /* |
| ** Execute zSql on database db. Return an error code. |
| */ |
| static int execSql(sqlite3 *db, char **pzErrMsg, const char *zSql){ |
| sqlite3_stmt *pStmt; |
| VVA_ONLY( int rc; ) |
| if( !zSql ){ |
| return SQLITE_NOMEM; |
| } |
| if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){ |
| sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db)); |
| return sqlite3_errcode(db); |
| } |
| VVA_ONLY( rc = ) sqlite3_step(pStmt); |
| assert( rc!=SQLITE_ROW ); |
| return vacuumFinalize(db, pStmt, pzErrMsg); |
| } |
| |
| /* |
| ** Execute zSql on database db. The statement returns exactly |
| ** one column. Execute this as SQL on the same database. |
| */ |
| static int execExecSql(sqlite3 *db, char **pzErrMsg, const char *zSql){ |
| sqlite3_stmt *pStmt; |
| int rc; |
| |
| rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0); |
| if( rc!=SQLITE_OK ) return rc; |
| |
| while( SQLITE_ROW==sqlite3_step(pStmt) ){ |
| rc = execSql(db, pzErrMsg, (char*)sqlite3_column_text(pStmt, 0)); |
| if( rc!=SQLITE_OK ){ |
| vacuumFinalize(db, pStmt, pzErrMsg); |
| return rc; |
| } |
| } |
| |
| return vacuumFinalize(db, pStmt, pzErrMsg); |
| } |
| |
| /* |
| ** The non-standard VACUUM command is used to clean up the database, |
| ** collapse free space, etc. It is modelled after the VACUUM command |
| ** in PostgreSQL. |
| ** |
| ** In version 1.0.x of SQLite, the VACUUM command would call |
| ** gdbm_reorganize() on all the database tables. But beginning |
| ** with 2.0.0, SQLite no longer uses GDBM so this command has |
| ** become a no-op. |
| */ |
| void sqlite3Vacuum(Parse *pParse){ |
| Vdbe *v = sqlite3GetVdbe(pParse); |
| if( v ){ |
| sqlite3VdbeAddOp2(v, OP_Vacuum, 0, 0); |
| } |
| return; |
| } |
| |
| /* |
| ** This routine implements the OP_Vacuum opcode of the VDBE. |
| */ |
| int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){ |
| int rc = SQLITE_OK; /* Return code from service routines */ |
| Btree *pMain; /* The database being vacuumed */ |
| Btree *pTemp; /* The temporary database we vacuum into */ |
| char *zSql = 0; /* SQL statements */ |
| int saved_flags; /* Saved value of the db->flags */ |
| int saved_nChange; /* Saved value of db->nChange */ |
| int saved_nTotalChange; /* Saved value of db->nTotalChange */ |
| void (*saved_xTrace)(void*,const char*); /* Saved db->xTrace */ |
| Db *pDb = 0; /* Database to detach at end of vacuum */ |
| int isMemDb; /* True if vacuuming a :memory: database */ |
| int nRes; /* Bytes of reserved space at the end of each page */ |
| int nDb; /* Number of attached databases */ |
| |
| if( !db->autoCommit ){ |
| sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction"); |
| return SQLITE_ERROR; |
| } |
| if( db->activeVdbeCnt>1 ){ |
| sqlite3SetString(pzErrMsg, db,"cannot VACUUM - SQL statements in progress"); |
| return SQLITE_ERROR; |
| } |
| |
| /* Save the current value of the database flags so that it can be |
| ** restored before returning. Then set the writable-schema flag, and |
| ** disable CHECK and foreign key constraints. */ |
| saved_flags = db->flags; |
| saved_nChange = db->nChange; |
| saved_nTotalChange = db->nTotalChange; |
| saved_xTrace = db->xTrace; |
| db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks | SQLITE_PreferBuiltin; |
| db->flags &= ~(SQLITE_ForeignKeys | SQLITE_ReverseOrder); |
| db->xTrace = 0; |
| |
| pMain = db->aDb[0].pBt; |
| isMemDb = sqlite3PagerIsMemdb(sqlite3BtreePager(pMain)); |
| |
| /* Attach the temporary database as 'vacuum_db'. The synchronous pragma |
| ** can be set to 'off' for this file, as it is not recovered if a crash |
| ** occurs anyway. The integrity of the database is maintained by a |
| ** (possibly synchronous) transaction opened on the main database before |
| ** sqlite3BtreeCopyFile() is called. |
| ** |
| ** An optimisation would be to use a non-journaled pager. |
| ** (Later:) I tried setting "PRAGMA vacuum_db.journal_mode=OFF" but |
| ** that actually made the VACUUM run slower. Very little journalling |
| ** actually occurs when doing a vacuum since the vacuum_db is initially |
| ** empty. Only the journal header is written. Apparently it takes more |
| ** time to parse and run the PRAGMA to turn journalling off than it does |
| ** to write the journal header file. |
| */ |
| nDb = db->nDb; |
| if( sqlite3TempInMemory(db) ){ |
| zSql = "ATTACH ':memory:' AS vacuum_db;"; |
| }else{ |
| zSql = "ATTACH '' AS vacuum_db;"; |
| } |
| rc = execSql(db, pzErrMsg, zSql); |
| if( db->nDb>nDb ){ |
| pDb = &db->aDb[db->nDb-1]; |
| assert( strcmp(pDb->zName,"vacuum_db")==0 ); |
| } |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| pTemp = db->aDb[db->nDb-1].pBt; |
| |
| /* The call to execSql() to attach the temp database has left the file |
| ** locked (as there was more than one active statement when the transaction |
| ** to read the schema was concluded. Unlock it here so that this doesn't |
| ** cause problems for the call to BtreeSetPageSize() below. */ |
| sqlite3BtreeCommit(pTemp); |
| |
| nRes = sqlite3BtreeGetReserve(pMain); |
| |
| /* A VACUUM cannot change the pagesize of an encrypted database. */ |
| #ifdef SQLITE_HAS_CODEC |
| if( db->nextPagesize ){ |
| extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*); |
| int nKey; |
| char *zKey; |
| sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey); |
| if( nKey ) db->nextPagesize = 0; |
| } |
| #endif |
| |
| /* Do not attempt to change the page size for a WAL database */ |
| if( sqlite3PagerGetJournalMode(sqlite3BtreePager(pMain)) |
| ==PAGER_JOURNALMODE_WAL ){ |
| db->nextPagesize = 0; |
| } |
| |
| if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes, 0) |
| || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes, 0)) |
| || NEVER(db->mallocFailed) |
| ){ |
| rc = SQLITE_NOMEM; |
| goto end_of_vacuum; |
| } |
| rc = execSql(db, pzErrMsg, "PRAGMA vacuum_db.synchronous=OFF"); |
| if( rc!=SQLITE_OK ){ |
| goto end_of_vacuum; |
| } |
| |
| #ifndef SQLITE_OMIT_AUTOVACUUM |
| sqlite3BtreeSetAutoVacuum(pTemp, db->nextAutovac>=0 ? db->nextAutovac : |
| sqlite3BtreeGetAutoVacuum(pMain)); |
| #endif |
| |
| /* Begin a transaction */ |
| rc = execSql(db, pzErrMsg, "BEGIN EXCLUSIVE;"); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| |
| /* Query the schema of the main database. Create a mirror schema |
| ** in the temporary database. |
| */ |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'CREATE TABLE vacuum_db.' || substr(sql,14) " |
| " FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'" |
| " AND rootpage>0" |
| ); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'CREATE INDEX vacuum_db.' || substr(sql,14)" |
| " FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %' "); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'CREATE UNIQUE INDEX vacuum_db.' || substr(sql,21) " |
| " FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %'"); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| |
| /* Loop through the tables in the main database. For each, do |
| ** an "INSERT INTO vacuum_db.xxx SELECT * FROM main.xxx;" to copy |
| ** the contents to the temporary database. |
| */ |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'INSERT INTO vacuum_db.' || quote(name) " |
| "|| ' SELECT * FROM main.' || quote(name) || ';'" |
| "FROM main.sqlite_master " |
| "WHERE type = 'table' AND name!='sqlite_sequence' " |
| " AND rootpage>0" |
| ); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| |
| /* Copy over the sequence table |
| */ |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'DELETE FROM vacuum_db.' || quote(name) || ';' " |
| "FROM vacuum_db.sqlite_master WHERE name='sqlite_sequence' " |
| ); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| rc = execExecSql(db, pzErrMsg, |
| "SELECT 'INSERT INTO vacuum_db.' || quote(name) " |
| "|| ' SELECT * FROM main.' || quote(name) || ';' " |
| "FROM vacuum_db.sqlite_master WHERE name=='sqlite_sequence';" |
| ); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| |
| |
| /* Copy the triggers, views, and virtual tables from the main database |
| ** over to the temporary database. None of these objects has any |
| ** associated storage, so all we have to do is copy their entries |
| ** from the SQLITE_MASTER table. |
| */ |
| rc = execSql(db, pzErrMsg, |
| "INSERT INTO vacuum_db.sqlite_master " |
| " SELECT type, name, tbl_name, rootpage, sql" |
| " FROM main.sqlite_master" |
| " WHERE type='view' OR type='trigger'" |
| " OR (type='table' AND rootpage=0)" |
| ); |
| if( rc ) goto end_of_vacuum; |
| |
| /* At this point, unless the main db was completely empty, there is now a |
| ** transaction open on the vacuum database, but not on the main database. |
| ** Open a btree level transaction on the main database. This allows a |
| ** call to sqlite3BtreeCopyFile(). The main database btree level |
| ** transaction is then committed, so the SQL level never knows it was |
| ** opened for writing. This way, the SQL transaction used to create the |
| ** temporary database never needs to be committed. |
| */ |
| { |
| u32 meta; |
| int i; |
| |
| /* This array determines which meta meta values are preserved in the |
| ** vacuum. Even entries are the meta value number and odd entries |
| ** are an increment to apply to the meta value after the vacuum. |
| ** The increment is used to increase the schema cookie so that other |
| ** connections to the same database will know to reread the schema. |
| */ |
| static const unsigned char aCopy[] = { |
| BTREE_SCHEMA_VERSION, 1, /* Add one to the old schema cookie */ |
| BTREE_DEFAULT_CACHE_SIZE, 0, /* Preserve the default page cache size */ |
| BTREE_TEXT_ENCODING, 0, /* Preserve the text encoding */ |
| BTREE_USER_VERSION, 0, /* Preserve the user version */ |
| }; |
| |
| assert( 1==sqlite3BtreeIsInTrans(pTemp) ); |
| assert( 1==sqlite3BtreeIsInTrans(pMain) ); |
| |
| /* Copy Btree meta values */ |
| for(i=0; i<ArraySize(aCopy); i+=2){ |
| /* GetMeta() and UpdateMeta() cannot fail in this context because |
| ** we already have page 1 loaded into cache and marked dirty. */ |
| sqlite3BtreeGetMeta(pMain, aCopy[i], &meta); |
| rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]); |
| if( NEVER(rc!=SQLITE_OK) ) goto end_of_vacuum; |
| } |
| |
| rc = sqlite3BtreeCopyFile(pMain, pTemp); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| rc = sqlite3BtreeCommit(pTemp); |
| if( rc!=SQLITE_OK ) goto end_of_vacuum; |
| #ifndef SQLITE_OMIT_AUTOVACUUM |
| sqlite3BtreeSetAutoVacuum(pMain, sqlite3BtreeGetAutoVacuum(pTemp)); |
| #endif |
| } |
| |
| assert( rc==SQLITE_OK ); |
| rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes,1); |
| |
| end_of_vacuum: |
| /* Restore the original value of db->flags */ |
| db->flags = saved_flags; |
| db->nChange = saved_nChange; |
| db->nTotalChange = saved_nTotalChange; |
| db->xTrace = saved_xTrace; |
| sqlite3BtreeSetPageSize(pMain, -1, -1, 1); |
| |
| /* Currently there is an SQL level transaction open on the vacuum |
| ** database. No locks are held on any other files (since the main file |
| ** was committed at the btree level). So it safe to end the transaction |
| ** by manually setting the autoCommit flag to true and detaching the |
| ** vacuum database. The vacuum_db journal file is deleted when the pager |
| ** is closed by the DETACH. |
| */ |
| db->autoCommit = 1; |
| |
| if( pDb ){ |
| sqlite3BtreeClose(pDb->pBt); |
| pDb->pBt = 0; |
| pDb->pSchema = 0; |
| } |
| |
| /* This both clears the schemas and reduces the size of the db->aDb[] |
| ** array. */ |
| sqlite3ResetInternalSchema(db, -1); |
| |
| return rc; |
| } |
| |
| #endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */ |