Sign InTry a questionToday's repAccept invitations

Sign In Try a question

← All coursesSuccessful Pipelines, Wrong Numbers6 levels · 32 lessons

A sync that exits 0 can leave the table empty~6 min
Three kinds of nothing~7 min
One NULL in a NOT IN list returns zero rows~8 min
COUNT counts rows, not things~9 min
A WHERE clause demotes your LEFT JOIN~8 min
Wrong Results at Query Time · Review~5 min

Streams, offsets, and consumption~9 min
The event arrived before the row~8 min
Your MERGE never sees the delete~9 min
Idempotency is a key, not a hope~8 min
A filter is not a deletion~8 min
Rows Missing From Incremental Loads · Review~5 min

Upstream renamed it, nothing failed~9 min
The schema held, the vocabulary moved~8 min
Types do not survive the layer boundary~8 min
Position binds the column, not the name~9 min
Schema Assumptions Nobody Checks · Review~5 min

A parse failure looks like no data~8 min
The same string, two different dates~8 min
Today's mapping rewrites last year's facts~8 min
The run that outgrew its interval~8 min
Bad Dates, Rewritten History and Overlapping Runs · Review~5 min

Lag propagates through tables, not views~10 min
Every refresh bills, even the empty ones~8 min
You busted the wrong cache~8 min
One character swallows every failure~8 min
Refresh, Cache, And The Bill · Review~5 min

Count parity as an alarm~10 min
Your diff and your database sort differently~8 min
The label is part of the number~8 min
A template bug is a data leak~8 min
Proving The Number, And Who May See It · Review~5 min

Course

Successful Pipelines, Wrong Numbers

Find the queries, loads and jobs that report success while writing wrong data.

Start free: A sync that exits 0 can leave the table empty

The levels

Level I · 6 lessonsWrong Results at Query Time