SQLite

  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_IOERR_NOMEM ){
      rc = SQLITE_NOMEM;
    }
    sqlite3Error(db, rc);
    goto opendb_out;
  }
  sqlite3BtreeEnter(db->aDb[0].pBt);
  db->aDb[0].pSchema = sqlite3SchemaGet(db, db->aDb[0].pBt);
  sqlite3BtreeLeave(db->aDb[0].pBt);
  db->aDb[1].pSchema = sqlite3SchemaGet(db, 0);

  /* The default safety_level for the main database is 'full'; for the temp
  ** database it is 'NONE'. This matches the pager layer defaults.  
  */
  db->aDb[0].zName = "main";
  db->aDb[0].safety_level = 3;

  launch_thread(&err, &threads, dynamic_triggers_2, 0);
  launch_thread(&err, &threads, dynamic_triggers_1, 0);

  join_all_threads(&err, &threads);

  print_and_free_err(&err);
}



#include "tt3_checkpoint.c"
#include "tt3_index.c"

int main(int argc, char **argv){
  struct ThreadTest {
    void (*xTest)(int);
    const char *zTest;
    int nMs;
  } aTest[] = {
    { walthread1, "walthread1", 20000 },
    { walthread2, "walthread2", 20000 },
    { walthread3, "walthread3", 20000 },
    { walthread4, "walthread4", 20000 },
    { walthread5, "walthread5",  1000 },
    { walthread5, "walthread5",  1000 },
    
    { cgt_pager_1,      "cgt_pager_1", 0 },
    { dynamic_triggers, "dynamic_triggers", 20000 },

    { checkpoint_starvation_1, "checkpoint_starvation_1", 10000 },
    { checkpoint_starvation_2, "checkpoint_starvation_2", 10000 },

    { create_drop_index_1, "create_drop_index_1", 10000 },
  };

  int i;
  char *zTest = 0;
  int nTest = 0;
  int bTestfound = 0;
  int bPrefix = 0;

/*
** 2014 December 9
**
** 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.
**
*************************************************************************
**
**     create_drop_index_1
*/


static char *create_drop_index_thread(int iTid, int iArg){
  Error err = {0};                /* Error code and message */
  Sqlite db = {0};                /* SQLite database connection */

  while( !timetostop(&err) ){
    opendb(&err, &db, "test.db", 0);

    sql_script(&err, &db, 

      "DROP INDEX IF EXISTS i1;"
      "DROP INDEX IF EXISTS i2;"
      "DROP INDEX IF EXISTS i3;"
      "DROP INDEX IF EXISTS i4;"

      "CREATE INDEX IF NOT EXISTS i1 ON t1(a);"
      "CREATE INDEX IF NOT EXISTS i2 ON t1(b);"
      "CREATE INDEX IF NOT EXISTS i3 ON t1(c);"
      "CREATE INDEX IF NOT EXISTS i4 ON t1(d);"

      "SELECT * FROM t1 ORDER BY a;"
      "SELECT * FROM t1 ORDER BY b;"
      "SELECT * FROM t1 ORDER BY c;"
      "SELECT * FROM t1 ORDER BY d;"
    );

    closedb(&err, &db);
  }

  print_and_free_err(&err);
  return sqlite3_mprintf("ok");
}

static void create_drop_index_1(int nMs){
  Error err = {0};
  Sqlite db = {0};
  Threadset threads = {0};

  opendb(&err, &db, "test.db", 1);
  sql_script(&err, &db, 
     "CREATE TABLE t1(a, b, c, d);"
     "WITH data(x) AS (SELECT 1 UNION ALL SELECT x+1 FROM data WHERE x<100) "
     "INSERT INTO t1 SELECT x,x,x,x FROM data;"
  );
  closedb(&err, &db);

  setstoptime(&err, nMs);

  sqlite3_enable_shared_cache(1);
  launch_thread(&err, &threads, create_drop_index_thread, 0);
  launch_thread(&err, &threads, create_drop_index_thread, 0);
  launch_thread(&err, &threads, create_drop_index_thread, 0);
  launch_thread(&err, &threads, create_drop_index_thread, 0);
  launch_thread(&err, &threads, create_drop_index_thread, 0);
  sqlite3_enable_shared_cache(0);

  join_all_threads(&err, &threads);
  print_and_free_err(&err);
}