如何使用SQLAlchemy設置SQLite PRAGMA語句

Question

我希望SQLAlchemy將SQLite .journal文件放在內存中以加速性能。我曾經嘗試這樣做：

sqlite_db_engine = create_engine('sqlite:///%s' % str(dbname), connect_args = {'PRAGMA  journal_mode':'MEMORY', 'PRAGMA synchronous':'OFF', 'PRAGMA temp_store':'MEMORY', 'PRAGMA cache_size':'5000000'}) 

db = sqlite_db_engine.connect() 

這：

sqlite_db_engine = create_engine('sqlite:///%s' % str(dbname)) 

db = sqlite_db_engine.connect() 
db.execute("PRAGMA journal_mode = MEMORY") 
db.execute("PRAGMA synchronous = OFF") 
db.execute("PRAGMA temp_store = MEMORY") 
db.execute("PRAGMA cache_size = 500000") 

沒有運氣。對於長時間交易，我仍然可以看到磁盤上創建的.journal文件。有沒有另外一種方法來設置它？

*注意我沒有問題與內置Python sqlite的模塊

Answer 1

這樣做基本上你應該能夠改寫有關外鍵的例子來實現你想要的。看看https://stackoverflow.com/a/7831210/1890086

engine = create_engine(database_url) 

def _fk_pragma_on_connect(dbapi_con, con_record): 
    dbapi_con.execute('PRAGMA journal_mode = MEMORY') 
    # ... 

from sqlalchemy import event 
event.listen(engine, 'connect', _fk_pragma_on_connect) 

Answer 2

如何使用事件：

from sqlalchemy.engine import Engine 
from sqlalchemy import event 

@event.listens_for(Engine, "connect") 
def set_sqlite_pragma(dbapi_connection, connection_record): 
    cursor = dbapi_connection.cursor() 
    cursor.execute("PRAGMA journal_mode=WAL") 
    cursor.close() 

見http://docs.sqlalchemy.org/en/rel_0_9/dialects/sqlite.html#foreign-key-support

Answer 3

兩個以前的解決方案沒有工作，所以我發現the another one。

from sqlalchemy.interfaces import PoolListener 
class MyListener(PoolListener): 
    def connect(self, dbapi_con, con_record): 
     dbapi_con.execute('pragma journal_mode=OFF') 
     dbapi_con.execute('PRAGMA synchronous=OFF') 
     dbapi_con.execute('PRAGMA cache_size=100000') 

engine = create_engine('sqlite:///' + basefile,echo=False, listeners= [MyListener()])