Database and table guidelines

When you are working with database tables, keep in mind the following guidelines:

• Pick the right data type or pick the right size. For example:
  • Use date (4 bytes) rather than datetime (8 bytes).
  • Use int1 (1 byte) or INT2 (2 bytes) rather than integer (4 bytes).
• Use the same data type and size for columns that you join against.
• Specify NOT NULL for columns, whenever possible.
  • NOT NULL requires less processing/instructions.
  • NOT NULL requires (slightly) less storage.
• Select a good distribution key, as described in Distribution keys.
• If necessary, specify organizing keys to improve queries on large fact tables, as described in Clustered base tables.
• Periodically generate statistics for the tables. See Database statistics.