datatypes_understanding_datatypes.md

title	area	layout	box_type	contributors
Understanding Datatypes	datatypes	faq	tip	jennaj garimavs

• Allow Galaxy to detect the datatype during Upload, and adjust from there if needed.
• Tool forms will filter for the appropriate datatypes it can use for each input.
• Directly changing a datatype can lead to errors. Be intentional and consider converting instead when possible.
• Dataset content can also be adjusted (tools: Data manipulation) and the expected datatype detected. Detected datatypes are the most reliable in most cases.
• If a tool does not accept a dataset as valid input, it is not in the correct format with the correct datatype.
• Once a dataset’s content matches the datatype, and that dataset is repeatedly used (example: Reference annotation) use that same dataset for all steps in an analysis or expect problems. This may mean rerunning prior tools if you need to make a correction.
• Tip: Not sure what datatypes a tool is expecting for an input?
  1. Create a new empty history
  2. Click on a tool from the tool panel
  3. The tool form will list the accepted datatypes per input
• Warning: In some cases, tools will transform a dataset to a new datatype at runtime for you.
  • This is generally helpful, and best reserved for smaller datasets.
  • Why? This can also unexpectedly create hidden datasets that are near duplicates of your original data, only in a different format.
  • For large data, that can quickly consume working space (quota).
  • Deleting/purging any hidden datasets can lead to errors if you are still using the original datasets as an input.
  • Consider converting to the expected datatype yourself when data is large.
  • Then test the tool directly on converted data. If it works, purge the original to recover space.