SQLite

        rc = walHashGet(pWal, iHash, &aHash, &aPgno, &iZero);
        if( rc==SQLITE_OK ){
          int i;
          int iMin = (iFirst - iZero);
          int iMax = (iHash==0) ? HASHTABLE_NPAGE_ONE : HASHTABLE_NPAGE;
          if( iMin<1 ) iMin = 1;
          if( iMax>head.mxFrame ) iMax = head.mxFrame;
          for(i=iMin; rc==SQLITE_OK && i<=iMax; i++){
            PgHdr *pPg;
            if( aPgno[i]==1 ){
              /* Check that the schema cookie has not been modified. If
              ** it has not, the commit can proceed. */
              u8 aNew[4];
              u8 *aOld = &((u8*)pPage1->pData)[40];
              int sz;

set ::testprefix concurrent3

if {$AUTOVACUUM} { finish_test ; return }
ifcapable !concurrent {
  finish_test
  return
}

db close
sqlite3_shutdown
#test_sqlite3_log xLog
#proc xLog {error_code msg} { puts "$error_code: $msg" }
reset_db

proc create_schema {} {
  db eval {
    PRAGMA journal_mode = wal;

    CREATE TABLE t1(x, y);
    CREATE TABLE t2(x, y);

    db eval {PRAGMA integrity_check}
  } {ok}

  foreach db $DBLIST { 
    $db close 
  }
}

#-------------------------------------------------------------------------
#
proc create_schema2 {} {
  db eval {
    PRAGMA journal_mode = wal;
    CREATE TABLE t1(x INTEGER PRIMARY KEY, y);
    CREATE INDEX i1 ON t1(y);
  }
}

proc randint {nMax} {
  db eval {SELECT abs(random() % $nMax)}
}

proc do_sql_op2 {db iOp} {
  switch -- $iOp {
    i {
      # Insert 1 rows.
      set r [randint 1000000000]
      set ::rows($r) 1
      #puts "insert row $r"
      $db eval { INSERT OR IGNORE INTO t1 VALUES($r, randomblob(50)); }
    }

    d {
      # Insert 1 row
      set keys [array names ::rows]
      set r [randint [llength $keys]]
      set rowid [lindex $keys $r]
      $db eval { DELETE FROM t1 WHERE x=$rowid }
      unset ::rows($rowid)
    }
  }
}

foreach {tn nRepeat oplist} {
  - - ----------------------------
  1 100 { 1iiiiiiiiii }
  2 100 { 1i 2d }
  3 100 { 1d 2i }
  4  50 { 1d 2i 3d }
  5 500 { 1i 2i 3i 4i }
} {
  if {[string range $oplist 0 0]=="-"} {
    array unset rows
    reset_db
    create_schema2
    continue
  }

  foreach db $DBLIST { 
    sqlite3 $db test.db 
    set stats($db,0) 0
    set stats($db,1) 0
  }
  array unset used

  do_test 2.$tn {

    for {set i 0} {$i < $nRepeat} {incr i} {
      foreach db $DBLIST { $db eval "BEGIN CONCURRENT" } 

      foreach op $oplist {
        set iDb [string range $op 0 0]
        set used(db$iDb) 1
        foreach char [split [string range $op 1 end] {}] {
          do_sql_op2 "db$iDb" $char
        }
      }

      foreach db $DBLIST { 
        if {$i==272 && $db=="db4"} breakpoint
        set rc [catch { $db eval COMMIT } msg]
        if {$rc} { $db eval ROLLBACK }
        incr stats($db,$rc)
      }
      set res [db eval {PRAGMA integrity_check}]
      if {$res != "ok"} { puts "after $db $rc: $res" ; after 1000000 }
    }
  } {}

  foreach db $DBLIST { 
    $db close 
  }
  foreach k [lsort [array names used]] {
    puts "$k: $stats($k,0) committed, $stats($k,1) rolled back"
  }
}



finish_test