Spark

TL;DR Batch processes bounded data on a schedule; streaming processes unbounded data continuously - different operational profiles, not a religious choice Streaming often costs 5-10x more per row than batch for the same volume; you pay for latency Streaming earns its keep when event value decays fast: fraud, ops alerts, live dashboards, inventory sync The lambda hybrid (streaming fast path + batch system of record) is what large platforms actually run Default to batch in 2026; add streaming only where latency genuinely matters, and land raw events in object storage from day one If you spend enough time in data engineering, you will eventually encounter the conviction that batch processing is dying and streaming is the future. This is the third or fourth time the industry has had this conversation in my career, and the answer has been the same every time. Streaming is not the future. Batch is not the past. They are different tools with different operational profiles, and the systems that age well use both, with discipline about which is the right choice for which problem. ...

How to Use This Guide This curated list covers courses from beginner to advanced levels across multiple platforms. Choose based on: Your role: Data Engineer, Data Analyst, or Data Scientist Learning style: Self-paced courses, specializations, or nanodegrees Timeline: Single courses (weeks) vs. comprehensive programs (months) Hands-on practice: Most include projects and real-world scenarios Cloud platform: AWS, GCP, Azure, or multi-cloud approaches Data Engineering Professional Certificates (Industry-Backed) Best for: Structured learning with recognized credentials ...

Quick Start This cheatsheet covers essential Databricks notebook commands, SQL operations, PySpark transformations, and optimization techniques for the lakehouse platform. Databricks Notebook Commands Magic commands provide shortcuts for common operations in Databricks notebooks: Command Purpose Use Case %python Executes python code (default language) PySpark transformations, data processing %sql Executes SQL queries Querying tables and views %scala Executes scala code Spark API operations, JVM access %r Execute R code Statistical analysis and visualization %sh Shell commands on cluster nodes Git operations, system utilities %fs Databricks file system operations File management, DBFS interactions %md Markdown text formatting Documentation and cell titles %pip Install Python packages Adding Python dependencies %env Set environment variables Configuration and secrets %config Notebook configuration options Display settings, execution parameters %jobs Lists all running jobs Job monitoring %load Load external file contents Include external code %reload Reload Python modules Refresh imports %run Execute another notebook Code reuse and modularization %lsmagic List all available magic commands Discovery %who List variables in current scope Debugging and variable inspection %matplotlib Configure matplotlib backend Visualization setup Notebook Widgets # Create widgets dbutils.widgets.text("param_name", "default_value", "label") dbutils.widgets.dropdown("param_name", "default", ["option1", "option2"]) dbutils.widgets.multiselect("param_name", "default", ["option1", "option2"]) dbutils.widgets.combobox("param_name", "default", ["option1", "option2"]) # Get widget values param_value = dbutils.widgets.get("param_name") # Remove widget dbutils.widgets.remove("param_name") dbutils.widgets.removeAll() Secrets Management # Create secret scope dbutils.secrets.createScope("scope_name") # Store secret dbutils.secrets.put("scope_name", "secret_key", "secret_value") # Retrieve secret secret_value = dbutils.secrets.get("scope_name", "secret_key") # List secrets dbutils.secrets.list("scope_name") # Delete secret dbutils.secrets.delete("scope_name", "secret_key") Accessing Files /path/to/file (local) dbfs:/path/to/file (DBFS) file:/path/to/file (driver filesystem) s3://path/to/file (S3) /Volumes/catalog/schema/volume/path (Unity Catalog Volumes) Copying Files %fs cp file:/<path> /Volumes/<catalog>/<schema>/<volume>/<path> %python dbutils.fs.cp("file:/<path>", "/Volumes/<catalog>/<schema>/<volume>/<path>") %python dbutils.fs.cp("file:/databricks/driver/test", "dbfs:/repo", True) %sh cp /<path> /Volumes/<catalog>/<schema>/<volume>/<path> SQL Statements DDL - Data Definition Language (Schema & Table Operations) Create & Use Schema CREATE SCHEMA test; CREATE SCHEMA custom LOCATION 'dbfs:/custom'; USE SCHEMA test; Unity Catalog (UC) -- Create catalog CREATE CATALOG my_catalog COMMENT "Production catalog"; -- Create schema in UC CREATE SCHEMA my_catalog.my_schema; USE CATALOG my_catalog; USE SCHEMA my_schema; -- Create volume (for files) CREATE VOLUME my_catalog.my_schema.my_volume; ALTER VOLUME my_catalog.my_schema.my_volume OWNER TO `team@company.com`; -- List catalogs, schemas, volumes SHOW CATALOGS; SHOW SCHEMAS IN my_catalog; SHOW VOLUMES IN my_catalog.my_schema; -- Grant permissions GRANT USAGE ON CATALOG my_catalog TO `user@company.com`; GRANT READ_VOLUME ON VOLUME my_catalog.my_schema.my_volume TO `user@company.com`; Create Table CREATE TABLE test(col1 INT, col2 STRING, col3 STRING, col4 BIGINT, col5 INT, col6 FLOAT); CREATE TABLE test AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv'); CREATE TABLE test USING CSV LOCATION '/repo/data/test.csv'; CREATE TABLE test USING CSV OPTIONS (header="true") LOCATION '/repo/data/test.csv'; CREATE TABLE test AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv'); CREATE TABLE test AS ... CREATE TABLE test USING ... CREATE TABLE test(id INT, title STRING, col1 STRING, publish_time BIGINT, pages INT, price FLOAT) COMMENT 'This is comment for the table itself'; CREATE TABLE test AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.json', format => 'json'); CREATE TABLE test_raw AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv', sep => ';'); CREATE TABLE custom_table_test LOCATION 'dbfs:/custom-table' AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv'); CREATE TABLE test PARTITIONED BY (col1) AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv') CREATE TABLE users( firstname STRING, lastname STRING, full_name STRING GENERATED ALWAYS AS (concat(firstname, ' ', lastname)) ); CREATE OR REPLACE TABLE test AS SELECT * EXCEPT (_rescued_data) FROM read_files('/repo/data/test.csv'); CREATE OR REPLACE TABLE test AS SELECT * FROM json.`/repo/data/test.json`; CREATE OR REPLACE TABLE test AS SELECT * FROM read_files('/repo/data/test.csv'); Create View CREATE VIEW view_test AS SELECT * FROM test WHERE col1 = 'test'; CREATE VIEW view_test AS SELECT col1, col1 FROM test JOIN test2 ON test.col2 == test2.col2; CREATE TEMP VIEW temp_test AS SELECT * FROM test WHERE col1 = 'test'; CREATE TEMP VIEW temp_test AS SELECT * FROM read_files('/repo/data/test.csv'); CREATE GLOBAL TEMP VIEW view_test AS SELECT * FROM test WHERE col1 = 'test'; SELECT * FROM global_temp.view_test; CREATE TEMP VIEW jdbc_example USING JDBC OPTIONS ( url "<jdbc-url>", dbtable "<table-name>", user '<username>', password '<password>'); CREATE OR REPLACE TEMP VIEW test AS SELECT * FROM delta.`<logpath>`; CREATE VIEW event_log_raw AS SELECT * FROM event_log("<pipeline-id>"); CREATE OR REPLACE TEMP VIEW test_view AS SELECT test.col1 AS col1 FROM test_table WHERE col1 = 'value1' ORDER BY timestamp DESC LIMIT 1; Drop & Describe DROP TABLE test; SHOW TABLES; DESCRIBE EXTENDED test; DML - Data Manipulation Language (Data Operations) Select SELECT * FROM csv.`/repo/data/test.csv`; SELECT * FROM read_files('/repo/data/test.csv'); SELECT * FROM read_files('/repo/data/test.csv', format => 'csv', header => 'true', sep => ',') SELECT * FROM json.`/repo/data/test.json`; SELECT * FROM json.`/repo/data/*.json`; SELECT * FROM test WHERE year(from_unixtime(test_time)) > 1900; SELECT * FROM test WHERE title LIKE '%a%' SELECT * FROM test WHERE title LIKE 'a%' SELECT * FROM test WHERE title LIKE '%a' SELECT * FROM test TIMESTAMP AS OF '2024-01-01T00:00:00.000Z'; SELECT * FROM test VERSION AS OF 2; SELECT * FROM test@v2; SELECT * FROM event_log("<pipeline-id>"); SELECT count(*) FROM VALUES (NULL), (10), (10) AS example(col); SELECT count(col) FROM VALUES (NULL), (10), (10) AS example(col); SELECT count_if(col1 = 'test') FROM test; SELECT from_unixtime(test_time) FROM test; SELECT cast(test_time / 1 AS timestamp) FROM test; SELECT cast(cast(test_time AS BIGINT) AS timestamp) FROM test; SELECT element.sub_element FROM test; SELECT flatten(array(array(1, 2), array(3, 4))); SELECT * FROM ( SELECT col1, col2 FROM test ) PIVOT ( sum(col1) for col2 in ('item1','item2') ); SELECT *, CASE WHEN col1 > 10 THEN 'value1' ELSE 'value2' END FROM test; SELECT * FROM test ORDER BY (CASE WHEN col1 > 10 THEN col2 ELSE col3 END); WITH t(col1, col2) AS (SELECT 1, 2) SELECT * FROM t WHERE col1 = 1; SELECT details:flow_definition.output_dataset as output_dataset, details:flow_definition.input_datasets as input_dataset FROM event_log_raw, latest_update WHERE event_type = 'flow_definition' AND origin.update_id = latest_update.id; Insert INSERT OVERWRITE test SELECT * FROM read_files('/repo/data/test.csv'); INSERT INTO test(col1, col2) VALUES ('value1', 'value2'); Merge Into MERGE INTO test USING test_to_delete ON test.col1 = test_to_delete.col1 WHEN MATCHED THEN DELETE; MERGE INTO test USING test_to_update ON test.col1 = test_to_update.col1 WHEN MATCHED THEN UPDATE SET *; MERGE INTO test USING test_to_insert ON test.col1 = test_to_insert.col1 WHEN NOT MATCHED THEN INSERT *; Copy Into COPY INTO test FROM '/repo/data' FILEFORMAT = CSV FILES = ('test.csv') FORMAT_OPTIONS('header' = 'true', 'inferSchema' = 'true'); Spark DataFrame API PySpark is the Python API for Apache Spark, enabling distributed data processing on the Databricks platform. ...