PostgreSQL's Quirky Grammar: A Deep Dive into the Parser
This article delves into some less-known aspects of PostgreSQL's grammar, including custom operators, precedence in compound SELECT statements, percent types, string continuation, quoted identifiers, and Unicode escapes. The author highlights that PostgreSQL's custom operators differ significantly from other mainstream languages, presenting unique implementation challenges. For instance, the support for custom operators allows native parsing of Trino's lambda expression syntax, but introduces precedence complexities. The article also details the nuanced behavior of string continuation and comments, explaining how to handle double quotes and Unicode escape sequences within identifiers. Finally, it demonstrates the use of operator functions, showcasing how to specify the operator's schema.
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