SQL Features

ANSI Mode (Enabled by Default)

ANSI mode is on by default in Spark 4.1.1, aligning Spark SQL with ANSI SQL standards. It enforces stricter rules for NULL handling, type conversions, and arithmetic.

spark.sql.ansi.enabled=true # default in Spark 4.1.1

Behavior changes vs Spark 3.x:

Operation

Spark 3.x

Spark 4.1.1 (ANSI default)

Integer overflow

Silent wrap-around

Throws ArithmeticException

Invalid type cast

Returns null

Throws AnalysisException

Division by zero

Returns null

Throws ArithmeticException

-- Throws ArithmeticException in Spark 4.1.1 SELECT 2147483647 + 1;

SQL Scripting (GA)

SQL Scripting is now Generally Available and enabled by default, transforming Spark SQL into a full programmable environment with loops, conditionals, variables, and error handling — directly in SQL.

New in 4.1.1: CONTINUE HANDLER for error recovery and multi-variable DECLARE syntax.

Example — control flow:

BEGIN DECLARE total_count INT DEFAULT 0; DECLARE dept_id INT DEFAULT 100; SET total_count = (SELECT COUNT(*) FROM employees WHERE department_id = dept_id); IF total_count > 50 THEN INSERT INTO large_departments VALUES (dept_id, total_count); ELSE INSERT INTO small_departments VALUES (dept_id, total_count); END IF; END;

Example — error handling with CONTINUE HANDLER:

BEGIN DECLARE CONTINUE HANDLER FOR SQLEXCEPTION INSERT INTO error_log VALUES (CURRENT_TIMESTAMP, 'Error occurred'); INSERT INTO target_table SELECT * FROM source_table; END;

VARIANT Data Type (GA)

The VARIANT data type is now Generally Available, providing a standardized way to store semi-structured data like JSON without rigid schemas. A major performance enhancement in 4.1.1 is shredding — commonly queried fields within a VARIANT column are automatically extracted and stored as typed Parquet columns, dramatically reducing I/O.

Performance benchmarks (shredded vs alternatives):

Comparison

Read Performance Gain

VARIANT with shredding vs non-shredded VARIANT

8x faster

VARIANT with shredding vs JSON strings

30x faster

Write performance (trade-off)

20–50% slower writes

Example:

from pyspark.sql import SparkSession spark = SparkSession.builder.appName("Variant Example").getOrCreate() # Create table with VARIANT column spark.sql(""" CREATE TABLE events ( id BIGINT, payload VARIANT ) USING PARQUET """) # Insert semi-structured data spark.sql(""" INSERT INTO events VALUES (1, parse_json('{"user": "alice", "action": "login", "score": 95}')), (2, parse_json('{"user": "bob", "action": "purchase", "amount": 49.99}')) """) # Query specific fields spark.sql("SELECT id, payload:user, payload:action FROM events").show()

Recursive CTE

Spark 4.1.1 adds native support for Recursive Common Table Expressions, enabling traversal of hierarchical data structures — org charts, bill of materials, graph topologies — directly in SQL.

Example — org chart traversal:

WITH RECURSIVE org_hierarchy AS ( -- Anchor: start with top-level managers SELECT employee_id, name, manager_id, 0 AS level FROM employees WHERE manager_id IS NULL UNION ALL -- Recursive: find each manager's direct reports SELECT e.employee_id, e.name, e.manager_id, oh.level + 1 FROM employees e JOIN org_hierarchy oh ON e.manager_id = oh.employee_id ) SELECT * FROM org_hierarchy ORDER BY level, name;

Approximate Data Sketches

Spark 4.1.1 expands approximate aggregation beyond HyperLogLog with two new native sketch types for efficient approximate analytics on massive datasets.

Sketch Type

SQL Function

Use Case

KLL (Quantiles)

kll_sketch_agg, kll_sketch_percentile

Approximate percentiles/quantiles with minimal memory

Theta

theta_sketch_agg, theta_sketch_distinct

Approximate set operations (union, intersection, difference)

KLL example — approximate percentiles:

-- Build a KLL sketch over a large column SELECT kll_sketch_agg(response_time_ms) AS response_sketch FROM request_logs; -- Query p50, p95, p99 from the sketch SELECT kll_sketch_percentile(response_sketch, array(0.5, 0.95, 0.99)) FROM (SELECT kll_sketch_agg(response_time_ms) AS response_sketch FROM request_logs);

Theta example — approximate distinct counts across datasets:

-- Approximate unique users across two date ranges SELECT theta_sketch_distinct( theta_sketch_union( (SELECT theta_sketch_agg(user_id) FROM events WHERE dt = '2025-01-01'), (SELECT theta_sketch_agg(user_id) FROM events WHERE dt = '2025-01-02') ) ) AS approx_unique_users_2days;

Collation Support

Spark 4.1.1 supports string collation, allowing locale-aware and case-insensitive string comparisons — essential for multilingual applications.

CREATE TABLE products (name STRING COLLATE 'en_US.UTF8'); SELECT * FROM products WHERE name = 'café' COLLATE 'en_US.UTF8';


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