Documenting NULL

Documenting NULL Tracking Document

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Commenters

• v1 to v3
  • David Rowley
  • Laurenz Albe
  • Thom Brown
  • Tom Lane
  • Yugo NAGATA
• v4 (first full proposal)
  • jian he
  • Marcos Pegoraro
  • Jeff Davis
• v5
  • Marcos Pegoraro

ToDo Note

• Check on implementation of comment regarding not null constraints (Laurenz)
• Examples feedback and editing pass (\pset null, quantity of) (jian)
• Consider another section with more guidance instead of rules (Jeff Davis)
• Consider one or more combined examples (Jeff Davis)
• Consider whether to call out count(*) on an empty set producing 0 instead of null (Jeff Davis)

Related Changes

• Syntax for The Null Value Constant
• Rewording tri-valued boolean logic

Main Section2s

• Meaning
  • Included the meanings/terms used in the PL languages included in core. (Marcos)
• Usage
  • Reconsider use of formal language (Jeff Davis).
  • Add subsections to this covering input/output/usage. (DGJ)
  • Mention that examples use \pset null <NULL>
• Distinctness
• Null-Valued Operands
• Null Values in Domains
• Testing Multi-Element Values with Null Elements
• Multi-Element Predicates and Scalars
• Multi-Element Comparisons
• Null-Valued Arguments in Normal Function Calls
• Null-Valued Arguments in Aggregate and Window Functions
• Null Values When Filtering
  • Frame up examples better and including/swapping-in a DISTINCT-using one (Marcos)
• Null Values in Table Constraints
• Null Values When Grouping
• Null Values When Ordering
• Null Values in Indexes
• Null Values in Partition Keys
  • Double-negative (jian)
• Null-Valued Settings
• Null Values in JSON
  • JSON Path considerations, is distinct from exclusion (Marcos)
  • Clean up wording around SQL null compare/contrast JSON null (jian)
  • Mention, as an aside, the case-sensitivity of the JSON null type's value. (Marcos)