We’re launching Lyria 3.5 in Google Flow Music, with advances across musicality, lyrics, vocals, and creative control
deepmind.google·6d ago
AI Engineering
Lobsters·20d ago·5 min read
The Order of Data: defaults, performance, determinism & paging
TL;DR
Postgres defaults to an insertion order when no ORDER BY clause is specified, leading to unpredictable results across different database implementations. This behavior can change with operations like DELETE and INSERT, which effectively reorder the data.
✦ Why It Matters
Engineers should always use ORDER BY in SQL queries to ensure predictable and consistent data retrieval.
Key Takeaways
- Always specify ORDER BY in SQL queries.
- Be aware of how DELETE and INSERT affect data order.
- Understand that default sorting can vary by database.
- Design queries to avoid reliance on implicit behavior.
Full Summary
In SQL, when an ORDER BY clause is omitted, the result order is undefined, varying by database implementation. In Postgres, the default order is typically the order of insertion, but this can be altered by performing DELETE and INSERT operations, which can lead to different sorting outcomes.
For instance, an UPDATE operation in Postgres is treated as a DELETE followed by an INSERT, thus affecting the order of returned results. This behavior highlights the importance of explicitly defining order in queries to avoid unexpected results.
Engineers should be aware that relying on default sorting can lead to inconsistencies, especially when data is modified. Understanding these nuances can help in designing more robust database interactions.