Common MySQL Commands: Databases, Users, and Grants
A quick-reference list of MySQL and MariaDB commands for databases, tables, users, and grants, kept for copy-pasting from the shell.
Writing
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Round Is Not Always What You Expect
Rounding the same float, 2.675, to two decimal places gives different answers in C#, PHP, Go, Python, JavaScript, and Ruby, for concrete reasons.
Materialized Views: Speeding Up Queries with a Tradeoff
Materialized views cache expensive PostgreSQL queries as physical tables, trading storage and refresh cost for fast reads, plus how pgpool fits in.
GitHub Actions Variables: env, Contexts, Secrets, and Matrix
How GitHub Actions variables work in practice: env blocks, context variables, secrets, matrix strategies, and passing step outputs between steps.
PostgreSQL Sequence Conflicts After an Upgrade: How to Fix Them
Upgrading PostgreSQL can leave sequences out of sync with table max values, causing duplicate-key errors and blocked sign-ins, fixed here with SQL and bash.
Upgrading to Rails 7.2: Four Breaking Changes We Hit
Four breaking changes we hit upgrading to Rails 7.2: show_exceptions, array-containment SQL, connection pool locking, and assert_enqueued_email_with.
Sending Pub/Sub Notifications to Slack With a Webhook
A small Node.js Cloud Function that decodes a Pub/Sub message, filters it by type, and forwards it to Slack through an incoming webhook.
fail vs raise in Ruby: They're the Same Method
Ruby's fail is a plain alias for raise, both dispatch to the same Kernel method, confirmed here in the C source and with an lldb backtrace.
delete_all vs destroy_all in Rails: Callbacks and Associations
delete_all skips callbacks and dependent associations while destroy_all runs them, and picking the wrong one silently breaks counter caches and cascades.
Floating-Point Precision in Ruby: Why 0.1 + 0.33 ≠ 0.43
Ruby's 0.1 + 0.33 does not equal 0.43 because of binary floating-point rounding, and Rational, BigDecimal, and tolerance comparisons each fix it differently.