/*
** 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,v 1.8 2003/08/15 13:24:52 drh Exp $
*/
#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 */
Parse *pParse; /* The parser context */
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( j<i ){
appendText(p, &zText[j], i-j);
}
appendText(p, "'", 1);
}
/*
** Execute statements of SQL. If an error occurs, write the error
** message into pParse->zErrMsg and return non-zero.
*/
static int execsql(Parse *pParse, sqlite *db, const char *zSql){
int rc;
char *zErrMsg = 0;
/* printf("***** executing *****\n%s\n", zSql); */
rc = sqlite_exec(db, zSql, 0, 0, &zErrMsg);
if( rc ){
sqliteErrorMsg(pParse, "%s", zErrMsg);
sqlite_freemem(zErrMsg);
}
return rc;
}
/*
** This is the second stage callback. Each invocation contains all the
** data for a single row of a single table in the original database. This
** routine must write that information into the new database.
*/
static int vacuumCallback2(void *pArg, int argc, char **argv, char **NotUsed){
vacuumStruct *p = (vacuumStruct*)pArg;
int rc = 0;
const char *zSep = "(";
int i;
if( argv==0 ) return 0;
p->s2.nUsed = 0;
appendText(&p->s2, "INSERT INTO ", -1);
appendQuoted(&p->s2, p->zTable);
appendText(&p->s2, " VALUES", -1);
for(i=0; i<argc; i++){
appendText(&p->s2, zSep, 1);
zSep = ",";
if( argv[i]==0 ){
appendText(&p->s2, "NULL", 4);
}else{
appendQuoted(&p->s2, argv[i]);
}
}
appendText(&p->s2,")", 1);
rc = execsql(p->pParse, p->dbNew, p->s2.z);
return 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->pParse, 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( rc && p->pParse->zErrMsg==0 ){
sqliteErrorMsg(p->pParse, "%s", zErrMsg);
}
}
return rc;
}
/*
** This callback is used to transfer PRAGMA settings from one database
** to the other. The value in argv[0] should be passed to a pragma
** identified by ((vacuumStruct*)pArg)->zPragma.
*/
static int vacuumCallback3(void *pArg, int argc, char **argv, char **NotUsed){
vacuumStruct *p = (vacuumStruct*)pArg;
int rc = 0;
char zBuf[200];
assert( argc==1 );
if( argv==0 ) return 0;
assert( argv[0]!=0 );
assert( strlen(p->zPragma)<100 );
assert( strlen(argv[0])<30 );
sprintf(zBuf,"PRAGMA %s=%s;", p->zPragma, argv[0]);
rc = execsql(p->pParse, p->dbNew, zBuf);
return rc;
}
/*
** Generate a random name of 20 character in length.
*/
static void randomName(char *zBuf){
static const char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"0123456789";
int i;
for(i=0; i<20; i++){
int n = sqliteRandomByte() % (sizeof(zChars)-1);
zBuf[i] = zChars[n];
}
}
#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){
#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 */
sqlite *db; /* The original database */
int rc = SQLITE_OK; /* Return code from service routines */
int i; /* Loop counter */
char *zErrMsg = 0; /* Error messages stored here */
int safety = 0; /* TRUE if safety is off */
vacuumStruct sVac; /* Information passed to callbacks */
/* These are all of the pragmas that need to be transferred over
** to the new database */
static const char *zPragma[] = {
"default_synchronous",
"default_cache_size",
/* "default_temp_store", */
};
/* Initial error checks
*/
if( pParse->explain ){
return;
}
db = pParse->db;
if( db->flags & SQLITE_InTrans ){
sqliteErrorMsg(pParse, "cannot VACUUM from within a transaction");
return;
}
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;
}
nFilename = strlen(zFilename);
zTemp = sqliteMalloc( nFilename+100 );
if( zTemp==0 ) return;
strcpy(zTemp, zFilename);
for(i=0; i<10; i++){
zTemp[nFilename] = '-';
randomName(&zTemp[nFilename+1]);
if( !sqliteOsFileExists(zTemp) ) break;
}
if( i>=10 ){
sqliteErrorMsg(pParse, "unable to create a temporary database file "
"in the same directory as the original database");
goto end_of_vacuum;
}
dbNew = sqlite_open(zTemp, 0, &zErrMsg);
if( dbNew==0 ){
sqliteErrorMsg(pParse, "unable to open a temporary database at %s - %s",
zTemp, zErrMsg);
goto end_of_vacuum;
}
if( sqliteSafetyOff(db) ){
sqliteErrorMsg(pParse, "library routines called out of sequence");
goto end_of_vacuum;
}
safety = 1;
if( execsql(pParse, db, "BEGIN") ) goto end_of_vacuum;
if( execsql(pParse, dbNew, "PRAGMA synchronous=off; BEGIN") ){
goto end_of_vacuum;
}
sVac.dbOld = db;
sVac.dbNew = dbNew;
sVac.pParse = pParse;
for(i=0; rc==SQLITE_OK && i<sizeof(zPragma)/sizeof(zPragma[0]); i++){
char zBuf[200];
assert( strlen(zPragma[i])<100 );
sprintf(zBuf, "PRAGMA %s;", zPragma[i]);
sVac.zPragma = zPragma[i];
rc = sqlite_exec(db, zBuf, vacuumCallback3, &sVac, &zErrMsg);
}
if( !rc ){
rc = sqlite_exec(db, "SELECT type, name, sql FROM sqlite_master "
"WHERE sql NOT NULL", vacuumCallback1, &sVac, &zErrMsg);
}
if( !rc ){
rc = sqliteBtreeCopyFile(db->aDb[0].pBt, dbNew->aDb[0].pBt);
sqlite_exec(db, "COMMIT", 0, 0, 0);
sqlite_exec(db, "ROLLBACK", 0, 0, 0); /* In case the COMMIT failed */
sqliteResetInternalSchema(db, 0);
}
end_of_vacuum:
if( rc && pParse->zErrMsg==0 && zErrMsg!=0 ){
sqliteErrorMsg(pParse, "unable to vacuum database - %s", zErrMsg);
}
if( safety ) {
sqlite_exec(db, "COMMIT", 0, 0, 0);
sqlite_exec(db, "ROLLBACK", 0, 0, 0); /* In case the COMMIT failed */
sqliteSafetyOn(db);
}
if( dbNew ) sqlite_close(dbNew);
sqliteOsDelete(zTemp);
sqliteFree(zTemp);
sqliteFree(sVac.s1.z);
sqliteFree(sVac.s2.z);
if( zErrMsg ) sqlite_freemem(zErrMsg);
return;
#endif
}