Best Practices (Maybe)

[BarryNorthey]

FWIW. I retired a few years ago but while working I found myself trying to help ArcGIS Desktop users troubleshoot their problems and eventually started a log of what I call best practices. Some of these might no longer be applicable and the Help available today is much improved over when I was working. When I started the GIS folks wore tie died T-shirts and spoke Unix. Please feel free to correct, add to, etc.

• Use a file geodatabase (FGDB) instead of shapefiles. Use shapefiles only when necessary.
• Be sure to (batch) run geoprocessing (GP) tool Repair Geometry on projected feature classes that are in FGDB or shapefile format (polygons and line features) unless you are certain that it has been done. This is especially important when using data from uncertain sources. I still do it on “official” government data sources and find errors.
• Compact (not Compress) your FGDBs from time to time.
• Some GP tools modify the source data. This can impact others if the data are shared with and used by others or between your Projects. Work on copies, especially if experimenting.
• Best GP performance is achieved when all inputs and outputs are in the same projected coordinate system.
• Consider using the Processing Extent environment when working on large datasets and a GP tool that honors it and creates a new output.
• Test a new procedure on a smaller subset of a large dataset and then apply it to the full dataset when satisfied that it is correct.
• Run large geoprocessing jobs after hours. These can be scheduled.
• Keep a backup of your important files in a secure location, not at c:\users. . . This is the default location for storing many files since everyone has that location.
• For safety, use the AGP Catalog tools to manage data whenever possible as opposed to File Explorer.
• Read the Tool Help prior to using an unfamiliar tool to make sure that it will run on your license level. This is most important for those using a Basic license and they need to be sure to check the Usage section for restrictions. Some tools require an extension such as Spatial Analyst.
• Keep file names short; avoid essays.  Use metadata instead to explain the data contents.  
• Fill in metadata as soon as possible after creating non temporary items that you want to retain while the details are still fresh in your mind.
• Some GP tools copy input metadata to the output and parts of the metadata might no longer apply. Always check and edit as needed.
• Avoid spaces in file and path names.  Use an underbar or CamelCase.
• Use alphanumeric characters when naming fields and always start field names with a letter.
• Avoid using keywords reserved by databases as field names. These include: date, day, month, table, text, user, when, where, year, ADD, ALTER, AND, BETWEEN, BY, COLUMN, CREATE, DELETE, DROP, EXISTS, FOR, FROM, GROUP, IN, INSERT, INTO, IS, LIKE, NOT, NULL, OR, ORDER, SELECT, SET, TABLE, UPDATE, VALUES, WHERE.
• Relational databases have enforced rules and won’t allow certain things whereas Excel worksheets are not databases and are more forgiving but getting better. If a field is supposed to hold numbers, make it a number field not a general field. Watch for illegal characters in delimited text files and worksheets.
• Don't send lock files when sharing FGDB or shapefile data.
• Be aware of the difference between NULL values and 0 especially when dealing with shapefiles.  Zero 0 is a number and is used in field calculations whereas NULL is not. The mean (average) of 4+8+0=4, whereas the mean of 4+8+NULL=6.