trouble using with synchronous access

[newville]

I'm trying to understand how to use this for synchronous access.

With the following script

import numpy as np
import zarr
from zarr_sqlite import SQLiteStore

import matplotlib.pyplot as plt
try:
 from wxmplot.interactive import imshow
except:
 imshow = None

def create_zarr_example(store_name, constructor, win=1):
 print(f"{store_name=} {constructor=}")

 opts = {'read_only': False}
 if constructor == zarr.storage.ZipStore:
 opts['mode'] = 'a'

 store = constructor(store_name, **opts)
 print("constructor worked: ", store)

 root = zarr.open_group(store=store)
 group1 = root.create_group('group1')

 x = np.arange(2000)/20.0
 y = x*x*1.e-3 + np.random.normal(size=2000, scale=0.5)
 x.shape = (50,40)
 y.shape = (50,40)

 group1.create_array(data=x, name='xdat')
 group1.create_array(data=y, name='ydat')

 print(group1, list(group1.keys()))
 store.close()

 ##
 read_store = constructor(store_name, **opts)
 nroot = zarr.open_group(read_store)
 ytest = nroot['group1/ydat'][()]

 print(f"## DONE {store_name=} {constructor=}")
 if imshow:
 imshow(ytest, win=win)
 else:
 plt.imshow(ytest)
 plt.show()

##############
storages = {'zarr1': zarr.storage.LocalStore,
 'zarr1.zip': zarr.storage.ZipStore,
 # 'zarr1.db': SQLiteStore,
 }

win = 0
for sname, constructor in storages.items():
 win += 1
 create_zarr_example(sname, constructor, win=win)

The LocalStore and ZipStore act almost identically -- a new store is created, data added, and can be retrieved. But trying this with SQLiteStore gives error messages that the database is not open.

I have not investigated thoroughly, but I suspect this is related to the async definition for open and maybe the use of asyncio for most of the interface. I think it is reasonable to except that synchronous access will be somewhat common. Any suggestions on where to loook for fixes to this? I'll admit to having only passing (are rarely "enjoyable") experience with asyncio - I completely get the desire for it here, but I also think that the maybe "obvious" use-case should also work.

Thanks

[newville]

@auxym Just as a follow-up, I think the main difficulties I was seeing were that:

a) mode='rw' will not create a new database. I think maybe

 query = {"mode": ["ro"] if read_only else ["rwc"]}

should be used in creating the database_uri. Another option would be for _open(), or perhaps _build_database_uri() to check for database existence, using "rwc" for databases that do not already exist.

b) it looks like Iterable needs to be imported even if TYPE_CHECKING is False. I think all the imports in the TYPE_CHECKING block should always be imported - they are actually used in the code.

Slightly unrelated, but maybe a feature request based on discussions in #4: maybe it would make sense to have a "pragma" dict, or support **kws as {pragma_name: pragma_value} in __init__() that get used at db creation time.