XML
XSLT Basics With Templates Match and Apply Templates
How an XSLT processor decides what to run: template match patterns, apply-templates, the built-in rules that dump text, modes, and the identity template.
6 min read
Tag
explainer
59 posts
CSVGuide
CSV Dialects and Variants You Will Run Into in Practice
The CSV dialects that exist in the wild, from RFC 4180 and Excel to PostgreSQL text, MySQL, TSV and pipes, with the settings that tell them apart.
19 min read
PostgreSQL
Partitioning Mistakes That Make PostgreSQL Queries Slower
Partitioning mistakes that make PostgreSQL queries slower: wrong key, too many partitions, id lookups, missing pruning, tiny partitions and fixes for each.
7 min read
JSONGuide
JSON Security Mistakes in Apps and Pipelines and Their Fixes
A tested guide to JSON security: where bodies turn hostile, parser differences, prototype pollution, SQL, limits, numbers, logs, and a checklist.
18 min read
CSV
Why a Hostile CSV Upload Can Hurt Your Application Server
A CSV upload needs no exploit to take a server down: compressed bombs, one huge field, an unclosed quote and wide files, each with the limit that stops it.
7 min read
CSVGuide
CSV Security Risks That Catch Teams Out and What to Do
How a CSV file hurts a team: formula injection, hostile uploads, leaked personal data, hidden payloads and risky loaders, with a fix and a check for each.
17 min read
PostgreSQL
Partition Pruning in PostgreSQL and Checking It Works
Partition pruning in PostgreSQL explained: plan time and run time pruning, what defeats it, how to read EXPLAIN output and a checklist for fixing queries.
7 min read
CSV
Why Excel Shows a CSV in One Column and What Causes It
Excel puts a whole CSV row in one cell for five different reasons. Learn how to tell which one you have by reading the first line of the file.
7 min read
CSV
Why Excel Drops Leading Zeros When You Open a CSV File
Why Excel turns 00123 into 123 when you double-click a CSV, what is lost on save, and how to keep zeros with the import wizard, Power Query or text columns.
6 min read
XML
Converting XML to JSON and the Attribute Problem Explained
XML has attributes, repeated children and mixed text, and JSON has objects and arrays. Where the mapping is lossy, what xmltodict does, and the fixes.
7 min read
Excel
Array Formulas and Why They Break Imports to Databases
How Excel array formulas and spilled ranges are stored in xlsx files, why loaders see blanks, extra cells or errors, and how to import them correctly.
7 min read
Excel
Differences Between Sheets and Excel Formulas to Know
How Google Sheets and Excel formulas differ: array handling, lookup and text functions, dates, locale, errors and what breaks when a file moves between them.
7 min read