这个问题与如何使用 Plone 和 RelStorage 打包 blobstorage 有关
使用带有RelStorage和 sqlite 的zodb数据库作为其后端，我正在尝试删除未使用的 blob。目前db.pack不会从光盘中删除 blob。下面的最小工作示例演示了这种行为：
import logging
import numpy as np
import os
import persistent
from persistent.list import PersistentList
import shutil
import time
from ZODB import config, blob
connectionString = """
%import relstorage
<zodb main>
<relstorage>
blob-dir ./blob
keep-history false
cache-local-mb 0
<sqlite3>
data-dir .
</sqlite3>
</relstorage>
</zodb>
"""
class Data(persistent.Persistent):
def __init__(self, data):
super().__init__()
self.children = PersistentList()
self.data = blob.Blob()
with self.data.open("w") as f:
np.save(f, data)
def main():
logging.basicConfig(level=logging.INFO)
# Initial cleanup
for f in os.listdir("."):
if f.endswith("sqlite3"):
os.remove(f)
if os.path.exists("blob"):
shutil.rmtree("blob", True)
# Initializing database
db = config.databaseFromString(connectionString)
with db.transaction() as conn:
root = Data(np.arange(10))
conn.root.Root = root
child = Data(np.arange(10))
root.children.append(child)
# Removing child reference from root
with db.transaction() as conn:
conn.root.Root.children.pop()
db.close()
print("blob directory:", [[os.path.join(rootDir, f) for f in files] for rootDir, _, files in os.walk("blob") if files])
db = config.databaseFromString(connectionString)
db.pack(time.time() + 1)
db.close()
print("blob directory:", [[os.path.join(rootDir, f) for f in files] for rootDir, _, files in os.walk("blob") if files])
if __name__ == "__main__":
main()
上面的示例执行以下操作：
- 删除当前目录中的任何以前的数据库以及 blob 目录。
- 从头开始创建一个数据库/存储，添加两个对象（root 和 child），而 child 由 root 引用并执行事务。
- 删除从根到子的链接并执行事务。
- 关闭数据库/存储
- 打开数据库/存储并
db.pack在未来执行一秒钟。
最小工作示例的输出如下：
INFO:ZODB.blob:(23376) Blob directory '<some path>/blob/' does not exist. Created new directory.
INFO:ZODB.blob:(23376) Blob temporary directory './blob/tmp' does not exist. Created new directory.
blob directory: [['blob/.layout'], ['blob/3/.lock', 'blob/3/0.03da352c4c5d8877.blob'], ['blob/6/.lock', 'blob/6/0.03da352c4c5d8877.blob']]
INFO:relstorage.storage.pack:pack: beginning pre-pack
INFO:relstorage.storage.pack:Analyzing transactions committed Thu Aug 27 11:48:17 2020 or before (TID 277592791412927078)
INFO:relstorage.adapters.packundo:pre_pack: filling the pack_object table
INFO:relstorage.adapters.packundo:pre_pack: Filled the pack_object table
INFO:relstorage.adapters.packundo:pre_pack: analyzing references from 7 object(s) (memory delta: 256.00 KB)
INFO:relstorage.adapters.packundo:pre_pack: objects analyzed: 7/7
INFO:relstorage.adapters.packundo:pre_pack: downloading pack_object and object_ref.
INFO:relstorage.adapters.packundo:pre_pack: traversing the object graph to find reachable objects.
INFO:relstorage.adapters.packundo:pre_pack: marking objects reachable: 4
INFO:relstorage.adapters.packundo:pre_pack: finished successfully
INFO:relstorage.storage.pack:pack: pre-pack complete
INFO:relstorage.adapters.packundo:pack: will remove 3 object(s)
INFO:relstorage.adapters.packundo:pack: cleaning up
INFO:relstorage.adapters.packundo:pack: finished successfully
blob directory: [['blob/.layout'], ['blob/3/.lock', 'blob/3/0.03da352c4c5d8877.blob'], ['blob/6/.lock', 'blob/6/0.03da352c4c5d8877.blob']]
如您所见db.pack，确实删除了 3 个对象“将删除 3 个对象”，但文件系统中的 blob 没有改变。
在 RelStorage 的单元测试中，它们似乎确实测试了是否从文件系统中删除了 blob（请参见此处），但在上面的脚本中它不起作用。
我究竟做错了什么？任何提示/链接/帮助表示赞赏。