var_samp() — PostgreSQL aggregate aggregate function

var_samp(): sample variance of bigint input values (square of the sample standard deviation). PostgreSQL aggregate functions — signature, volatility, version applicability and an illustrative example.

The Sev-1 Admin
The Sev-1 Admin  ·  2 min read

Summary

var_samp is a PostgreSQL built-in aggregate function in the Aggregate Functions group. PostgreSQL’s system catalog (pg_proc) describes it as: “sample variance of bigint input values (square of the sample standard deviation)”.

Signature

var_samp has 6 documented overloaded forms:

var_samp(bigint) → numeric
var_samp(integer) → numeric
var_samp(smallint) → numeric
var_samp(real) → double precision
var_samp(double precision) → double precision
var_samp(numeric) → numeric

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: Aggregate Functions
  • Kind: Aggregate 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: double precision, numeric

Example

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

SELECT var_samp(col) FROM your_table;

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

var_samp 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 — Aggregate Functions.