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External Resources — DBRE & SQL

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Curated external links — bookmarks worth keeping open.

Official Documentation

Database Official Docs Notes
PostgreSQL postgresql.org/docs/current Definitive reference — search here before Stack Overflow
MySQL dev.mysql.com/doc InnoDB internals, replication, optimizer trace
MariaDB mariadb.com/kb/en MySQL fork with additional features
Oracle DB docs.oracle.com/en/database Enterprise reference; PL/SQL, RAC, Data Guard
MongoDB mongodb.com/docs Aggregation pipeline, schema design, indexing
Redis redis.io/docs Commands reference, persistence, cluster config
Cassandra cassandra.apache.org/doc CQL, data modeling, compaction strategies
ClickHouse clickhouse.com/docs MergeTree engines, SQL extensions, materialized views
Amazon Aurora aws.amazon.com/rds/aurora/faqs Storage architecture, failover, Serverless v2
Amazon DynamoDB docs.aws.amazon.com/dynamodb Key design, GSIs, Streams, Global Tables
Google Cloud Spanner cloud.google.com/spanner/docs TrueTime, interleaving, global ACID
Azure Cosmos DB learn.microsoft.com/azure/cosmos-db Consistency levels, partitioning, multi-API
CockroachDB cockroachlabs.com/docs Distributed SQL, geo-partitioning, Raft
PlanetScale planetscale.com/docs Schema branching, Vitess, non-blocking DDL
Valkey (Redis fork) valkey.io Open-source Redis fork maintained by AWS/Google post license change

PostgreSQL

SQL Anti-Patterns & Bad Habits

Resource What it is
sqlblog.org/bad-habits Aaron Bertrand's "Bad Habits to Kick" series — practical, opinionated, production-focused.
sqlblog.org SQL Server and general SQL blog with performance, indexing, and query tuning deep dives.

PostgreSQL Wiki: Don't Do This — Quick Reference

The most useful items from the wiki (go read the full page):

Data Types - Don't use char(n) — use text or varchar - Don't use money — use numeric - Don't use timestamp without time zone — use timestamptz - Don't use serial — use identity columns (PostgreSQL 10+)

Authentication & Security - Don't use trust auth in production - Don't use superuser for application connections

Queries - Don't use BETWEEN for timestamp ranges (use >= and <) - Don't use NOT IN with a subquery — use NOT EXISTS - Don't use UPPER()/LOWER() for case-insensitive search — use citext or ILIKE - Don't use LIKE '%foo%' for search — use full-text search or pg_trgm

Schema - Don't use NULL to mean "false" or "zero" - Don't use EAV (Entity-Attribute-Value) tables

→ Full list: wiki.postgresql.org/wiki/Don't_Do_This

Aaron Bertrand's Bad Habits — Quick Reference

From sqlblog.org/bad-habits:

Naming - Using reserved words as identifiers - Using sp_ prefix for stored procedures (conflicts with system procs) - Inconsistent naming conventions

Queries - SELECT * in production code - Using NOLOCK / READ UNCOMMITTED as a performance fix - Putting GETDATE() in a WHERE clause on an indexed column - Using BETWEEN for date ranges (off-by-one errors) - Implicit column list in INSERT

Schema Design - Using VARCHAR(MAX) everywhere instead of appropriate sizes - Storing delimited lists in a single column - Not using NOT NULL constraints by default

Performance - Cursors and row-by-row processing instead of set-based operations - Over-indexing (too many indexes slow down writes)

→ Full series: sqlblog.org/bad-habits

modern-sql.com Highlights