SQLite

      while( ALWAYS(p) && p->pNext!=pIndex ){ p = p->pNext; }
      if( ALWAYS(p && p->pNext==pIndex) ){
        p->pNext = pIndex->pNext;
      }
    }
    freeIndex(db, pIndex);
  }
  db->flags |= SQLITE_InternChanges;
}

/*
** Look through the list of open database files in db->aDb[] and if
** any have been closed, remove them from the list.  Reallocate the
** db->aDb[] structure to a smaller size, if possible.
**

  sqlite3BtreeEnterAll(db);
  for(i=0; i<db->nDb; i++){
    Db *pDb = &db->aDb[i];
    if( pDb->pSchema ){
      sqlite3SchemaClear(pDb->pSchema);
    }
  }
  db->flags &= ~SQLITE_InternChanges;
  sqlite3VtabUnlockList(db);
  sqlite3BtreeLeaveAll(db);
  sqlite3CollapseDatabaseArray(db);
}

/*
** This routine is called when a commit occurs.
*/
void sqlite3CommitInternalChanges(sqlite3 *db){
  db->flags &= ~SQLITE_InternChanges;
}

/*
** Delete memory allocated for the column names of a table or view (the
** Table.aCol[] array).
*/
void sqlite3DeleteColumnNames(sqlite3 *db, Table *pTable){

  assert( iDb>=0 && iDb<db->nDb );
  assert( zTabName );
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
  pDb = &db->aDb[iDb];
  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName, 0);
  sqlite3DeleteTable(db, p);
  db->flags |= SQLITE_InternChanges;
}

/*
** Given a token, return a string that consists of the text of that
** token.  Space to hold the returned string
** is obtained from sqliteMalloc() and must be freed by the calling
** function.

    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName, p);
    if( pOld ){
      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
      sqlite3OomFault(db);
      return;
    }
    pParse->pNewTable = 0;
    db->flags |= SQLITE_InternChanges;

#ifndef SQLITE_OMIT_ALTERTABLE
    if( !p->pSelect ){
      const char *zName = (const char *)pParse->sNameToken.z;
      int nName;
      assert( !pSelect && pCons && pEnd );
      if( pCons->z==0 ){

    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 
                          pIndex->zName, pIndex);
    if( p ){
      assert( p==pIndex );  /* Malloc must have failed */
      sqlite3OomFault(db);
      goto exit_create_index;
    }
    db->flags |= SQLITE_InternChanges;
    if( pTblName!=0 ){
      pIndex->tnum = db->init.newTnum;
    }
  }

  /* If this is the initial CREATE INDEX statement (or CREATE TABLE if the
  ** index is an implied index for a UNIQUE or PRIMARY KEY constraint) then

    }
    case SQLITE_DBCONFIG_LOOKASIDE: {
      void *pBuf = va_arg(ap, void*); /* IMP: R-26835-10964 */
      int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
      int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
      rc = setupLookaside(db, pBuf, sz, cnt);
      break;
    }
    case SQLITE_DBCONFIG_FULL_EQP: {
      int onoff = va_arg(ap, int);
      int *pRes = va_arg(ap, int*);
      if( onoff>0 ){
        db->bFullEQP = 1;
      }else if( onoff==0 ){
        db->bFullEQP = 0;
      }
      sqlite3ExpirePreparedStatements(db);
      if( pRes ){
        *pRes = db->bFullEQP;
      }
      rc = SQLITE_OK;
      break;
    }
    default: {
      static const struct {
        int op;      /* The opcode */
        u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
      } aFlagOp[] = {
        { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
        { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
        { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
        { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
        { SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE,      SQLITE_NoCkptOnClose  },

      };
      unsigned int i;
      rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
      for(i=0; i<ArraySize(aFlagOp); i++){
        if( aFlagOp[i].op==op ){
          int onoff = va_arg(ap, int);
          int *pRes = va_arg(ap, int*);

  /* Obtain all b-tree mutexes before making any calls to BtreeRollback(). 
  ** This is important in case the transaction being rolled back has
  ** modified the database schema. If the b-tree mutexes are not taken
  ** here, then another shared-cache connection might sneak in between
  ** the database rollback and schema reset, which can cause false
  ** corruption reports in some cases.  */
  sqlite3BtreeEnterAll(db);
  schemaChange = (db->flags & SQLITE_InternChanges)!=0 && db->init.busy==0;

  for(i=0; i<db->nDb; i++){
    Btree *p = db->aDb[i].pBt;
    if( p ){
      if( sqlite3BtreeIsInTrans(p) ){
        inTrans = 1;
      }
      sqlite3BtreeRollback(p, tripCode, !schemaChange);
    }
  }
  sqlite3VtabRollback(db);
  sqlite3EndBenignMalloc();

  if( (db->flags&SQLITE_InternChanges)!=0 && db->init.busy==0 ){
    sqlite3ExpirePreparedStatements(db);
    sqlite3ResetAllSchemasOfConnection(db);
  }
  sqlite3BtreeLeaveAll(db);

  /* Any deferred constraint violations have now been resolved. */
  db->nDeferredCons = 0;

**
** After a database is initialized, the DB_SchemaLoaded bit is set
** bit is set in the flags field of the Db structure. If the database
** file was of zero-length, then the DB_Empty flag is also set.
*/
int sqlite3Init(sqlite3 *db, char **pzErrMsg){
  int i, rc;
  int commit_internal = !(db->flags&SQLITE_InternChanges);
  
  assert( sqlite3_mutex_held(db->mutex) );
  assert( sqlite3BtreeHoldsMutex(db->aDb[0].pBt) );
  assert( db->init.busy==0 );
  rc = SQLITE_OK;
  db->init.busy = 1;
  ENC(db) = SCHEMA_ENC(db);

  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
  u8 suppressErr;               /* Do not issue error messages if true */
  u8 vtabOnConflict;            /* Value to return for s3_vtab_on_conflict() */
  u8 isTransactionSavepoint;    /* True if the outermost savepoint is a TS */
  u8 mTrace;                    /* zero or more SQLITE_TRACE flags */
  u8 skipBtreeMutex;            /* True if no shared-cache backends */
  u8 nSqlExec;                  /* Number of pending OP_SqlExec opcodes */
  u8 bFullEQP;                  /* Include triggers in EQP output */
  int nextPagesize;             /* Pagesize after VACUUM if >0 */
  u32 magic;                    /* Magic number for detect library misuse */
  int nChange;                  /* Value returned by sqlite3_changes() */
  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
  int aLimit[SQLITE_N_LIMIT];   /* Limits */
  int nMaxSorterMmap;           /* Maximum size of regions mapped by sorter */
  struct sqlite3InitInfo {      /* Information used during initialization */

**
** Value constraints (enforced via assert()):
**      SQLITE_FullFSync     == PAGER_FULLFSYNC
**      SQLITE_CkptFullFSync == PAGER_CKPT_FULLFSYNC
**      SQLITE_CacheSpill    == PAGER_CACHE_SPILL
*/
#define SQLITE_VdbeTrace      0x00000001  /* True to trace VDBE execution */
#define SQLITE_InternChanges  0x00000002  /* Uncommitted Hash table changes */
#define SQLITE_FullColNames   0x00000004  /* Show full column names on SELECT */
#define SQLITE_FullFSync      0x00000008  /* Use full fsync on the backend */
#define SQLITE_CkptFullFSync  0x00000010  /* Use full fsync for checkpoint */
#define SQLITE_CacheSpill     0x00000020  /* OK to spill pager cache */
#define SQLITE_ShortColNames  0x00000040  /* Show short columns names */
#define SQLITE_CountRows      0x00000080  /* Count rows changed by INSERT, */
                                          /*   DELETE, or UPDATE and return */

    if( pTrigger->pSchema==pTrigger->pTabSchema ){
      Table *pTab = tableOfTrigger(pTrigger);
      Trigger **pp;
      for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
      *pp = (*pp)->pNext;
    }
    sqlite3DeleteTrigger(db, pTrigger);
    db->flags |= SQLITE_InternChanges;
  }
}

/*
** pEList is the SET clause of an UPDATE statement.  Each entry
** in pEList is of the format <id>=<expr>.  If any of the entries
** in pEList have an <id> which matches an identifier in pIdList,

        }
        db->isTransactionSavepoint = 0;
        rc = p->rc;
      }else{
        int isSchemaChange;
        iSavepoint = db->nSavepoint - iSavepoint - 1;
        if( p1==SAVEPOINT_ROLLBACK ){
          isSchemaChange = (db->flags & SQLITE_InternChanges)!=0;
          for(ii=0; ii<db->nDb; ii++){
            rc = sqlite3BtreeTripAllCursors(db->aDb[ii].pBt,
                                       SQLITE_ABORT_ROLLBACK,
                                       isSchemaChange==0);
            if( rc!=SQLITE_OK ) goto abort_due_to_error;
          }
        }else{
          isSchemaChange = 0;
        }
        for(ii=0; ii<db->nDb; ii++){
          rc = sqlite3BtreeSavepoint(db->aDb[ii].pBt, p1, iSavepoint);
          if( rc!=SQLITE_OK ){
            goto abort_due_to_error;
          }
        }
        if( isSchemaChange ){
          sqlite3ExpirePreparedStatements(db);
          sqlite3ResetAllSchemasOfConnection(db);
          db->flags = (db->flags | SQLITE_InternChanges);
        }
      }
  
      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all 
      ** savepoints nested inside of the savepoint being operated on. */
      while( db->pSavepoint!=pSavepoint ){
        pTmp = db->pSavepoint;

  assert( pDb->pBt!=0 );
  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
  /* See note about index shifting on OP_ReadCookie */
  rc = sqlite3BtreeUpdateMeta(pDb->pBt, pOp->p2, pOp->p3);
  if( pOp->p2==BTREE_SCHEMA_VERSION ){
    /* When the schema cookie changes, record the new cookie internally */
    pDb->pSchema->schema_cookie = pOp->p3;
    db->flags |= SQLITE_InternChanges;
  }else if( pOp->p2==BTREE_FILE_FORMAT ){
    /* Record changes in the file format */
    pDb->pSchema->file_format = pOp->p3;
  }
  if( pOp->p1==1 ){
    /* Invalidate all prepared statements whenever the TEMP database
    ** schema is changed.  Ticket #1644 */

  int nSub = 0;                        /* Number of sub-vdbes seen so far */
  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = &p->aMem[1];             /* First Mem of result set */
  int bFull = (p->explain==1 || db->bFullEQP);
  Op *pOp = 0;

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );

  /* Even though this opcode does not use dynamic strings for