/* ** 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. ** ** $Id: vacuum.c 875429 2008-10-24 12:20:41Z cgilles $ */ #include "sqliteInt.h" #include "os.h" /* ** A structure for holding a dynamic string - a string that can grow ** without bound. */ typedef struct dynStr dynStr; struct dynStr { char *z; /* Text of the string in space obtained from sqliteMalloc() */ int nAlloc; /* Amount of space allocated to z[] */ int nUsed; /* Next unused slot in z[] */ }; /* ** A structure that holds the vacuum context */ typedef struct vacuumStruct vacuumStruct; struct vacuumStruct { sqlite *dbOld; /* Original database */ sqlite *dbNew; /* New database */ char **pzErrMsg; /* Write errors here */ int rc; /* Set to non-zero on an error */ const char *zTable; /* Name of a table being copied */ const char *zPragma; /* Pragma to execute with results */ dynStr s1, s2; /* Two dynamic strings */ }; #if !defined(SQLITE_OMIT_VACUUM) || SQLITE_OMIT_VACUUM /* ** Append text to a dynamic string */ static void appendText(dynStr *p, const char *zText, int nText){ if( nText<0 ) nText = strlen(zText); if( p->z==0 || p->nUsed + nText + 1 >= p->nAlloc ){ char *zNew; p->nAlloc = p->nUsed + nText + 1000; zNew = sqliteRealloc(p->z, p->nAlloc); if( zNew==0 ){ sqliteFree(p->z); memset(p, 0, sizeof(*p)); return; } p->z = zNew; } memcpy(&p->z[p->nUsed], zText, nText+1); p->nUsed += nText; } /* ** Append text to a dynamic string, having first put the text in quotes. */ static void appendQuoted(dynStr *p, const char *zText){ int i, j; appendText(p, "'", 1); for(i=j=0; zText[i]; i++){ if( zText[i]=='\'' ){ appendText(p, &zText[j], i-j+1); j = i + 1; appendText(p, "'", 1); } } if( js2.nUsed = 0; appendText(&p->s2, "INSERT INTO ", -1); appendQuoted(&p->s2, p->zTable); appendText(&p->s2, " VALUES", -1); for(i=0; is2, zSep, 1); zSep = ","; if( argv[i]==0 ){ appendText(&p->s2, "NULL", 4); }else{ appendQuoted(&p->s2, argv[i]); } } appendText(&p->s2,")", 1); p->rc = execsql(p->pzErrMsg, p->dbNew, p->s2.z); return p->rc; } /* ** This is the first stage callback. Each invocation contains three ** arguments where are taken from the SQLITE_MASTER table of the original ** database: (1) the entry type, (2) the entry name, and (3) the SQL for ** the entry. In all cases, execute the SQL of the third argument. ** For tables, run a query to select all entries in that table and ** transfer them to the second-stage callback. */ static int vacuumCallback1(void *pArg, int argc, char **argv, char **NotUsed){ vacuumStruct *p = (vacuumStruct*)pArg; int rc = 0; assert( argc==3 ); if( argv==0 ) return 0; assert( argv[0]!=0 ); assert( argv[1]!=0 ); assert( argv[2]!=0 ); rc = execsql(p->pzErrMsg, p->dbNew, argv[2]); if( rc==SQLITE_OK && strcmp(argv[0],"table")==0 ){ char *zErrMsg = 0; p->s1.nUsed = 0; appendText(&p->s1, "SELECT * FROM ", -1); appendQuoted(&p->s1, argv[1]); p->zTable = argv[1]; rc = sqlite_exec(p->dbOld, p->s1.z, vacuumCallback2, p, &zErrMsg); if( zErrMsg ){ sqliteSetString(p->pzErrMsg, zErrMsg, (char*)0); sqlite_freemem(zErrMsg); } } if( rc!=SQLITE_ABORT ) p->rc = rc; return rc; } /* ** Generate a random name of 20 character in length. */ static void randomName(unsigned char *zBuf){ static const unsigned char zChars[] = "abcdefghijklmnopqrstuvwxyz" "0123456789"; int i; sqliteRandomness(20, zBuf); for(i=0; i<20; i++){ zBuf[i] = zChars[ zBuf[i]%(sizeof(zChars)-1) ]; } } #endif /* ** 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 sqliteVacuum(Parse *pParse, Token *pTableName){ Vdbe *v = sqliteGetVdbe(pParse); sqliteVdbeAddOp(v, OP_Vacuum, 0, 0); return; } /* ** This routine implements the OP_Vacuum opcode of the VDBE. */ int sqliteRunVacuum(char **pzErrMsg, sqlite *db){ #if !defined(SQLITE_OMIT_VACUUM) || SQLITE_OMIT_VACUUM const char *zFilename; /* full pathname of the database file */ int nFilename; /* number of characters in zFilename[] */ char *zTemp = 0; /* a temporary file in same directory as zFilename */ sqlite *dbNew = 0; /* The new vacuumed database */ int rc = SQLITE_OK; /* Return code from service routines */ int i; /* Loop counter */ char *zErrMsg; /* Error message */ vacuumStruct sVac; /* Information passed to callbacks */ if( db->flags & SQLITE_InTrans ){ sqliteSetString(pzErrMsg, "cannot VACUUM from within a transaction", (char*)0); return SQLITE_ERROR; } if( db->flags & SQLITE_Interrupt ){ return SQLITE_INTERRUPT; } memset(&sVac, 0, sizeof(sVac)); /* Get the full pathname of the database file and create two ** temporary filenames in the same directory as the original file. */ zFilename = sqliteBtreeGetFilename(db->aDb[0].pBt); if( zFilename==0 ){ /* This only happens with the in-memory database. VACUUM is a no-op ** there, so just return */ return SQLITE_OK; } nFilename = strlen(zFilename); zTemp = sqliteMalloc( nFilename+100 ); if( zTemp==0 ) return SQLITE_NOMEM; strcpy(zTemp, zFilename); for(i=0; i<10; i++){ zTemp[nFilename] = '-'; randomName((unsigned char*)&zTemp[nFilename+1]); if( !sqliteOsFileExists(zTemp) ) break; } if( i>=10 ){ sqliteSetString(pzErrMsg, "unable to create a temporary database file " "in the same directory as the original database", (char*)0); goto end_of_vacuum; } dbNew = sqlite_open(zTemp, 0, &zErrMsg); if( dbNew==0 ){ sqliteSetString(pzErrMsg, "unable to open a temporary database at ", zTemp, " - ", zErrMsg, (char*)0); goto end_of_vacuum; } if( (rc = execsql(pzErrMsg, db, "BEGIN"))!=0 ) goto end_of_vacuum; if( (rc = execsql(pzErrMsg, dbNew, "PRAGMA synchronous=off; BEGIN"))!=0 ){ goto end_of_vacuum; } sVac.dbOld = db; sVac.dbNew = dbNew; sVac.pzErrMsg = pzErrMsg; if( rc==SQLITE_OK ){ rc = sqlite_exec(db, "SELECT type, name, sql FROM sqlite_master " "WHERE sql NOT NULL AND type!='view' " "UNION ALL " "SELECT type, name, sql FROM sqlite_master " "WHERE sql NOT NULL AND type=='view'", vacuumCallback1, &sVac, &zErrMsg); } if( rc==SQLITE_OK ){ int meta1[SQLITE_N_BTREE_META]; int meta2[SQLITE_N_BTREE_META]; sqliteBtreeGetMeta(db->aDb[0].pBt, meta1); sqliteBtreeGetMeta(dbNew->aDb[0].pBt, meta2); meta2[1] = meta1[1]+1; meta2[3] = meta1[3]; meta2[4] = meta1[4]; meta2[6] = meta1[6]; rc = sqliteBtreeUpdateMeta(dbNew->aDb[0].pBt, meta2); } if( rc==SQLITE_OK ){ rc = sqliteBtreeCopyFile(db->aDb[0].pBt, dbNew->aDb[0].pBt); sqlite_exec(db, "COMMIT", 0, 0, 0); sqliteResetInternalSchema(db, 0); } end_of_vacuum: if( rc && zErrMsg!=0 ){ sqliteSetString(pzErrMsg, "unable to vacuum database - ", zErrMsg, (char*)0); } sqlite_exec(db, "ROLLBACK", 0, 0, 0); if( (dbNew && (dbNew->flags & SQLITE_Interrupt)) || (db->flags & SQLITE_Interrupt) ){ rc = SQLITE_INTERRUPT; } if( dbNew ) sqlite_close(dbNew); sqliteOsDelete(zTemp); sqliteFree(zTemp); sqliteFree(sVac.s1.z); sqliteFree(sVac.s2.z); if( zErrMsg ) sqlite_freemem(zErrMsg); if( rc==SQLITE_ABORT && sVac.rc!=SQLITE_INTERRUPT ) sVac.rc = SQLITE_ERROR; return sVac.rc; #endif }