SQLite

//
cmd ::= DROP INDEX ifexists(E) fullname(X).   {sqlite3DropIndex(pParse, X, E);}

///////////////////////////// The VACUUM command /////////////////////////////
//
%ifndef SQLITE_OMIT_VACUUM
%ifndef SQLITE_OMIT_ATTACH
%type vinto {Expr*}
%destructor vinto {sqlite3ExprDelete(pParse->db, $$);}
cmd ::= VACUUM vinto(Y).                {sqlite3Vacuum(pParse,0,Y);}
cmd ::= VACUUM nm(X) vinto(Y).          {sqlite3Vacuum(pParse,&X,Y);}
vinto(A) ::= INTO expr(X).              {A = X;}
vinto(A) ::= .                          {A = 0;}
%endif  SQLITE_OMIT_ATTACH
%endif  SQLITE_OMIT_VACUUM

///////////////////////////// The PRAGMA command /////////////////////////////
//
%ifndef SQLITE_OMIT_PRAGMA
cmd ::= PRAGMA nm(X) dbnm(Z).                {sqlite3Pragma(pParse,&X,&Z,0,0);}

#define LOCATE_VIEW    0x01
#define LOCATE_NOERR   0x02
Table *sqlite3LocateTable(Parse*,u32 flags,const char*, const char*);
Table *sqlite3LocateTableItem(Parse*,u32 flags,struct SrcList_item *);
Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
void sqlite3Vacuum(Parse*,Token*,Expr*);
int sqlite3RunVacuum(char**, sqlite3*, int, sqlite3_value*);
char *sqlite3NameFromToken(sqlite3*, Token*);
int sqlite3ExprCompare(Parse*,Expr*, Expr*, int);
int sqlite3ExprCompareSkip(Expr*, Expr*, int);
int sqlite3ExprListCompare(ExprList*, ExprList*, int);
int sqlite3ExprImpliesExpr(Parse*,Expr*, Expr*, int);
int sqlite3ExprImpliesNonNullRow(Expr*,int);
void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);

** the copy of step (3) were replaced by deleting the original database
** and renaming the transient database as the original.  But that will
** not work if other processes are attached to the original database.
** And a power loss in between deleting the original and renaming the
** transient would cause the database file to appear to be deleted
** following reboot.
*/
void sqlite3Vacuum(Parse *pParse, Token *pNm, Expr *pInto){
  Vdbe *v = sqlite3GetVdbe(pParse);
  int iDb = 0;

  if( v==0 ) goto build_vacuum_end;
  if( pNm ){
#ifndef SQLITE_BUG_COMPATIBLE_20160819
    /* Default behavior:  Report an error if the argument to VACUUM is
    ** not recognized */
    iDb = sqlite3TwoPartName(pParse, pNm, pNm, &pNm);
    if( iDb<0 ) goto build_vacuum_end;
#else
    /* When SQLITE_BUG_COMPATIBLE_20160819 is defined, unrecognized arguments
    ** to VACUUM are silently ignored.  This is a back-out of a bug fix that
    ** occurred on 2016-08-19 (https://www.sqlite.org/src/info/083f9e6270).
    ** The buggy behavior is required for binary compatibility with some
    ** legacy applications. */
    iDb = sqlite3FindDb(pParse->db, pNm);
    if( iDb<0 ) iDb = 0;
#endif
  }
  if( iDb!=1 ){
    int iIntoReg = 0;

    if( pInto ){
      iIntoReg = ++pParse->nMem;
      sqlite3ExprCode(pParse, pInto, iIntoReg);
    }
    sqlite3VdbeAddOp2(v, OP_Vacuum, iDb, iIntoReg);
    sqlite3VdbeUsesBtree(v, iDb);
  }
build_vacuum_end:
  sqlite3ExprDelete(pParse->db, pInto);
  return;
}

/*
** This routine implements the OP_Vacuum opcode of the VDBE.
*/
int sqlite3RunVacuum(
  char **pzErrMsg,        /* Write error message here */
  sqlite3 *db,            /* Database connection */
  int iDb,                /* Which attached DB to vacuum */
  sqlite3_value *pOut     /* Write results here, if not NULL */
){
  int rc = SQLITE_OK;     /* Return code from service routines */
  Btree *pMain;           /* The database being vacuumed */
  Btree *pTemp;           /* The temporary database we vacuum into */
  u32 saved_mDbFlags;     /* Saved value of db->mDbFlags */
  u64 saved_flags;        /* Saved value of db->flags */
  int saved_nChange;      /* Saved value of db->nChange */
  int saved_nTotalChange; /* Saved value of db->nTotalChange */
  u8 saved_mTrace;        /* Saved trace settings */
  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 */
  const char *zDbMain;    /* Schema name of database to vacuum */
  const char *zOut;       /* Name of output file */

  if( !db->autoCommit ){
    sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction");
    return SQLITE_ERROR;
  }
  if( db->nVdbeActive>1 ){
    sqlite3SetString(pzErrMsg, db,"cannot VACUUM - SQL statements in progress");
    return SQLITE_ERROR;
  }
  if( pOut ){
    if( sqlite3_value_type(pOut)!=SQLITE_TEXT ){
      sqlite3SetString(pzErrMsg, db, "non-text filename");
      return SQLITE_ERROR;
    }
    zOut = (const char*)sqlite3_value_text(pOut);
  }else{
    zOut = "";
  }

  /* 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_mDbFlags = db->mDbFlags;
  saved_nChange = db->nChange;

  ** 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;
  rc = execSqlF(db, pzErrMsg, "ATTACH %Q AS vacuum_db", zOut);
  if( rc!=SQLITE_OK ) goto end_of_vacuum;
  assert( (db->nDb-1)==nDb );
  pDb = &db->aDb[nDb];
  assert( strcmp(pDb->zDbSName,"vacuum_db")==0 );
  pTemp = pDb->pBt;
  if( pOut ){
    sqlite3_file *id = sqlite3PagerFile(sqlite3BtreePager(pTemp));
    i64 sz = 0;
    if( id->pMethods!=0 && (sqlite3OsFileSize(id, &sz)!=SQLITE_OK || sz>0) ){
      rc = SQLITE_ERROR;
      sqlite3SetString(pzErrMsg, db, "output file already exists");
      goto end_of_vacuum;
    }

  /* Begin a transaction and take an exclusive lock on the main database
  ** file. This is done before the sqlite3BtreeGetPageSize(pMain) call below,
  ** to ensure that we do not try to change the page-size on a WAL database.
  */
  rc = execSql(db, pzErrMsg, "BEGIN");
  if( rc!=SQLITE_OK ) goto end_of_vacuum;
  rc = sqlite3BtreeBeginTrans(pMain, pOut==0 ? 2 : 0, 0);
  if( rc!=SQLITE_OK ) goto end_of_vacuum;

  /* Do not attempt to change the page size for a WAL database */
  if( sqlite3PagerGetJournalMode(sqlite3BtreePager(pMain))
                                               ==PAGER_JOURNALMODE_WAL ){
    db->nextPagesize = 0;
  }

       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 */
       BTREE_APPLICATION_ID,     0,  /* Preserve the application id */
    };

    assert( 1==sqlite3BtreeIsInTrans(pTemp) );
    assert( pOut!=0 || 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;
    }

    if( pOut==0 ){
      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
    if( pOut==0 ){
      sqlite3BtreeSetAutoVacuum(pMain, sqlite3BtreeGetAutoVacuum(pTemp));
    }
#endif
  }

  assert( rc==SQLITE_OK );
  if( pOut==0 ){
    rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes,1);
  }

end_of_vacuum:
  /* Restore the original value of db->flags */
  db->init.iDb = 0;
  db->mDbFlags = saved_mDbFlags;

  sqlite3VdbeChangeEncoding(pOut, encoding);
  if( rc ) goto abort_due_to_error;
  break;
};
#endif /* SQLITE_OMIT_PRAGMA */

#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
/* Opcode: Vacuum P1 P2 * * *
**
** Vacuum the entire database P1.  P1 is 0 for "main", and 2 or more
** for an attached database.  The "temp" database may not be vacuumed.
**
** If P2 is not zero, then it is a register holding a string which is
** the file into which the result of vacuum should be written.  When
** P2 is zero, the vacuum overwrites the original database.
*/
case OP_Vacuum: {
  assert( p->readOnly==0 );
  rc = sqlite3RunVacuum(&p->zErrMsg, db, pOp->p1,
                        pOp->p2 ? &aMem[pOp->p2] : 0);
  if( rc ) goto abort_due_to_error;
  break;
}
#endif

#if !defined(SQLITE_OMIT_AUTOVACUUM)
/* Opcode: IncrVacuum P1 P2 * * *

do_catchsql_test vacuum-into-150 {
  VACUUM INTO 'out2.db';
} {1 {output file already exists}}

do_catchsql_test vacuum-into-200 {
  VACUUM main INTO ':memory:';
} {0 {}}

# The INTO argument can be an arbitrary expression.
#
do_execsql_test vacuum-into-300 {
  CREATE TABLE t2(name TEXT);
  INSERT INTO t2 VALUES(':memory:');
  VACUUM main INTO (SELECT name FROM t2);
} {}
do_catchsql_test vacuum-into-310 {
  VACUUM INTO null;
} {1 {non-text filename}}

finish_test