Page History
...
These are examples of getting data over HTTPS from a batch node from within cori; needless to say, the URL prefix is https://pswww-dev.slac.stanford.edu/calib_ws
Two users:
- mongo --host=psdb-dev --port 9306 -u "dubrovin" -p "...." --authenticationDatabase "admin"
- mongo --host=psdb-dev --port 9306 -u "calibuser" -p "...." --authenticationDatabase "admin"
Test commands:
- curl -s "https://pswww-dev.slac.stanford.edu/calib_ws/test_db/test_coll/5b649a9df59ae00bda110168"
- curl -s "https://pswww-dev.slac.stanford.edu/calib_ws/test_db/test_coll"
- curl -s "https://pswww-dev.slac.stanford.edu/calib_ws/test_db/test_coll?item=planner&size.uom=cm"
- curl -s "https://pswww-dev.slac.stanford.edu/calib_ws/test_db/test_coll?query_string=%7B%20%22item%22%3A%20%22planner%22%2C%20%22qty%22%3A%2075%20%7D%0A"
Summary
- MongoDB structure has limitations in number of levels and document size.
- server may have many DBs
- DB is a container for collections
- collection is a group of documents
- document is a JSON/BSON object of key:value pairs (dictionary). Each value may be dictionary itself etc, but further structure levels are not supported by DB structure.
- document size has hardwired limit 16MB (in 2010 increased from 4 to 16MB and devs do not want to change it). CSPAD 2Mpix*8byte(double) = 16MB, but we may expect larger detectors like Jungfrau, Epix, Andor, etc.
- Larger data size is suggested to save using GridFS; split data for chanks and save chunks in the same DB in different collections.
- JSON (text) object in MongoDB is presented in unicode...(UTF-8). Data should be converted to unicode force and back in saving retrieving.
- schema-less DB looks interesting to certain extents, but in order to find something in DB there should be a schema...
- GridFS works fine with document size>16GB.
...
Overview
Content Tools