xmlexists() — PostgreSQL mathematical function

xmlexists(): test XML value against XPath expression. PostgreSQL mathematical functions — signature, volatility, version applicability and an illustrative example.

The Sev-1 Admin
The Sev-1 Admin  ·  1 min read

Summary

xmlexists is a PostgreSQL built-in function in the Mathematical Functions group. PostgreSQL’s system catalog (pg_proc) describes it as: “test XML value against XPath expression”.

Signature

xmlexists(text, xml) → boolean

Argument and return types are taken from the pg_proc catalog; internal type names are shown using their readable SQL spellings (for example int4 is shown as integer). (Derived from the catalog — see the linked reference for the canonical documentation.)

Classification

  • Category: Mathematical Functions
  • Kind: Function
  • Volatility: IMMUTABLE — Marked IMMUTABLE — it always returns the same result for the same arguments and can be used in indexes and other contexts that require immutability.
  • Returns: boolean

Example

Illustrative form (replace placeholder values with your own data):

SELECT xmlexists('abc', NULL::xml);

The example above is illustrative and is meant to show calling syntax only; consult the linked PostgreSQL documentation for exact semantics, edge cases and accepted argument combinations.

Version applicability

xmlexists is present across the surveyed releases (PostgreSQL 15, 16, 17, 18, 19). On older major versions, behaviour may differ in detail — always check the documentation for the version you run.

Related & references

Reference: PostgreSQL documentation — Mathematical Functions.