wiki:DC3BDataAccess
Last modified 10 years ago Last modified on 07/21/2009 12:33:43 AM

Data Access Plans for DC3b

In scope:

Issues to be resolved:

  • Image servers (for postage stamp generation) may not be needed if local-disk sky tile caches can be used.

Actions:

  • K-T to discuss MOPS requirements with Francesco (by 6/5)
  • K-T to publish persistence framework design proposal and iterate with Middleware and Data Access WGs (by 6/12)
  • Martin/Jim? to propose sky tessellation including size of sky tiles (by ?)
  • Data Access WG to discuss local-disk caching and postage stamp generation (by 6/12)

Design goals for persistence:

  • Emphasize persistence from Python, not C++
    • Python class returns non-LSST-specific persistence descriptor
  • MOPS requires object update and complex object-to-table mappings
    • Shallow and deep fetches, joins and where clauses
  • Separate formatters per storage
  • Add simple layer without platform/storage-independence features (for use in non-pipeline contexts only)
    • Attempt to replace Exposure's writeFits()

Possible design for Multifit:

  • Decide on sky tessellation including size of sky tiles
    • Tangent planes are good enough
    • Sky tiles may need to overlap
  • Provide sky tile-sized regions for co-add/detection
    • Coadd can have same pixel scale as images
  • Provide local cache for sky tiles
  • Provide local postage stamp cutout capabilities for measurement