create data export example

[prjemian]

Create an example notebook showing how to move scans from from broker to another using the Broker API.

Related to a need at APS 3-ID-D

[prjemian]

These are the contents of the sqlite directory just after the exception:

-rw-r--r-- 1 user group    0 Nov  9 16:40 6ea22d45-7b57-4936-b007-a6129a04a28c.sqlite
-rw-r--r-- 1 user group    2 Nov  9 16:40 event_descriptors.json
-rw-r--r-- 1 user group 5.7K Nov  9 16:40 run_starts.json
-rw-r--r-- 1 user group    2 Nov  9 16:41 run_stops.json

[prjemian]

OperationalError: duplicate column name: data_NFS

There is only one data column with "NFS" in it.

Seems be trouble creating ophyd object names with the data column names that have embedded whitespace. These names come from the text in the scaler channel labels. It was OK to acquire data with such names.

Looks like an assumption bug to me in the export code. Either of these places:

• databroker/headersource/core.py
• databroker/headersource/sqlite.py

[prjemian]

@TCaswell : FYI only. In a recent zoom meeting, I mentioned previous problems trying to move data between two mongodb servers for databroker. You emphasized the importance of reporting problems. This issue records part of that problem, which continues to sit untouched. Not sure this ever rose to the level of bug report since I was learning at the time.

Since there is renewed attention on moving data between databroker instances with the Pilot project, this could follow that effort.

[prjemian]

So, still not a problem to be fixed but rather a procedure to be determined.

[prjemian]

Follow this comment for 4-ID-C Polar,

pip install databroker-pack
databroker-pack mongodb_config --copy-external --query '{"scan_id": {"$in": [135, 136, 137]}}' exported_scans

Be careful about the use of single-quotes and double-quotes above; they matter.

Other search criteria are possible, using the mongodb-query language.

[prjemian]

This command was a successful export:

databroker-pack mongodb_config -q "TimeRange(since='2020-09-01', until='2020-09-02')" /tmp/0901

Now, what about in a jupyter notebook?

[prjemian]

No notebook example here, the python API looks complicated, in favor of command-line tools. Maybe a markdown page showing how to use the command-line tools.

[prjemian]

See the documentation for instructions to pack and unpack. The documentation addresses the copy from broker to broker using the command-line tools.