Appendix B: Operator Reference

TL;DR

This is the quick lookup for predicate operators. Prefer this list when you need exact spellings and current behavior.

You can always inspect live support with:

./build/markql --mode plain --color=disabled --query "SHOW OPERATORS;"

Current operators in this build:

• = equality
• <> inequality
• <, <=, >, >= ordered comparison
• IN (...) membership
• LIKE SQL wildcard (%, _)
• CONTAINS, CONTAINS ALL, CONTAINS ANY
• IS NULL, IS NOT NULL
• HAS_DIRECT_TEXT (legacy shorthand; prefer DIRECT_TEXT(tag) LIKE '%...%')
• ~ regex match
• AND, OR

Practical guidance

• Prefer LIKE for text wildcard filtering.
• Prefer EXISTS(descendant WHERE ...) for structural gating.
• Keep predicates simple and composable while exploring.