Author | Lightnews

Franck Pachot @franckpachot.bsky.social · 1d

I believe those looking to time-partition by UUID are working with databases that lack global indexes to enforce unique constraints beyond the partition key. Or sharding those partitions

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Franck Pachot @franckpachot.bsky.social · 5d

I enjoy staying connected with multiple database communities. Even if I share more about one today 🌱🐅, I'm happy to have feedback from others 🅾️🔸️🐘🐬 on what I share

Franck Pachot @franckpachot.bsky.social · 6d

Sad times where tech giant billionaires fire people to build datacenters in a giant game of Monopoly

Brian Merchant @bcmerchant.bsky.social · 7d

From an Amazon Employees for Climate Justice statement:

“They’re pushing this narrative that AI is transformative and that’s why they’re making these cuts. But leadership is spending 100 billion this year alone on the new data centers; they have to find that money elsewhere,” said one AWS engineer.

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Franck Pachot @franckpachot.bsky.social · 13d

A migration tool vendor suggests that migration is necessary for improved consistency, reliability, and advanced query capabilities. Yet, success often comes from first understanding your current database. Questioning these claims is the occasion to learn:
dev.to/franckpachot...

Advanced Query Capabilities 👉🏻 aggregation pipelines

Although MongoDB has supported ACID transactions and sophisticated aggregation features for years,...

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Franck Pachot @franckpachot.bsky.social · 19d

I'm curious to find out whether Oracle still uses DerbyDB in their Oracle Database Appliances to store the metadata, and what they will replace it with

Erik C. Thauvin @erik.thauvin.net · 19d

Derby DB to be retired!

#apache #database #java

issues.apache.org/jira/...

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Franck Pachot @franckpachot.bsky.social · 21d

If the banner has AI in lower and upper case, it must be great

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Franck Pachot @franckpachot.bsky.social · Oct 3

SELECT DISTINCT ON ... ORDER BY equivalent in MongoDB (and faster)

dev.to/franckpachot...

First/Last per Group: PostgreSQL DISTINCT ON and MongoDB DISTINCT_SCAN Performance

On Stack Overflow, the most frequent question for PostgreSQL is: "Select first row in each GROUP BY...

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Franck Pachot @franckpachot.bsky.social · Oct 1

Was just trying to be funny 😭 AI and vibe coding, resulting in too many buffer pins

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Franck Pachot @franckpachot.bsky.social · Oct 1

I can think of 100s of reasons but you said 23ai, so... vibe pinning?

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Franck Pachot @franckpachot.bsky.social · Sep 29

More WiredTiger internals: persisting MongoDB's committed MVCC versions through checkpoints and restarts dev.to/franckpachot...

WiredTigerHS.wt: MongoDB MVCC Durable History Store

MongoDB uses the WiredTiger storage engine, which implements Multi‑Version Concurrency Control (MVCC)...

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Reposted by Franck Pachot

Roscoe Rubin-Rottenberg @knotbin.com · Sep 28

Trust me I was so against it when I arrived at spark I’ve used it in the past and hated it.
but the lack of relations is actually amazing for backfill. it just makes it so simple and painless that I’m willing to live with the mongo of it all

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Franck Pachot @franckpachot.bsky.social · Sep 26

and store the buffer in aifiedt.buf to be more AI friendly

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Reposted by Franck Pachot

Jonathan Lewis @jloracle.bsky.social · Sep 24

Blog post for September 2025

SQL Developer isn't entirely CBO-friendly.
jonathanlewis.wordpress.com/2025/09/24/s...

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Franck Pachot @franckpachot.bsky.social · Sep 22

A closer look at MongoDB Text Search: which terms are indexed for a string, how they're stored, and what formula is used to calculate the query's matching score. Since it's based on Lucene, let's use Lucene tools. dev.to/franckpachot...

MongoDB Search Index Internals with Luke (Lucene Toolbox GUI tool)

Previously, I demonstrated MongoDB text search scoring with a simple example, creating a dynamic...

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Franck Pachot @franckpachot.bsky.social · Sep 19

Comparing 🍏 to 🍊, and MongoDB to PostgreSQL, with full-text search indexes

dev.to/franckpachot...

Text Search with MongoDB and PostgreSQL

MongoDB Search Indexes provide full‑text search capabilities directly within MongoDB, allowing...

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Franck Pachot @franckpachot.bsky.social · Sep 18

An example of MongoDB aggregation pipeline compared to the equivalent in SQL/JSON with common table expressions (CTE), from a StackOverflow question: dev.to/franckpachot...

Combine Two JSON Collections with Nested Arrays: MongoDB and PostgreSQL Aggregations

Suppose you need to merge two sources of data—both JSON documents containing nested arrays. This was...

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Franck Pachot @franckpachot.bsky.social · Sep 16

A flexible schema permits arrays in fields without upfront declaration, and filters and indexes (multiple keys per document) use it automatically. MongoDB tracks multikey paths in indexed fields to optimize index scans:

dev.to/franckpachot...

MongoDB Multikey Indexes and Index Bound Optimization

Previously, I discussed how MongoDB keeps track of whether indexed fields contain arrays. This...

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Franck Pachot @franckpachot.bsky.social · Sep 15

MongoDB’s strength is not only in its flexible, document-oriented API, but also in its ability to store documents to disk without random I/O slicing or vacuuming later. Here's how MongoDB persists collections and indexes in WiredTiger:

dev.to/franckpachot...

MongoDB Internals: How Collections and Indexes Are Stored in WiredTiger

WiredTiger is MongoDB’s default storage engine, but what really occurs behind the scenes when...

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Franck Pachot @franckpachot.bsky.social · Sep 9

Encryption is not yet there in PostgreSQL

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Franck Pachot @franckpachot.bsky.social · Sep 9

As that's on disk and malicious users with host access may access memory, the only full protection is encryption from the client. MongoDB has such queryable encryption:
www.mongodb.com/docs/manual/...

Queryable Encryption - Database Manual - MongoDB Docs

www.mongodb.com

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Franck Pachot @franckpachot.bsky.social · Sep 9

Yes, more difficult as you have to calculate checksum and propagate to parent. Encryption protects from reading/changing block content

Franck Pachot @franckpachot.bsky.social · Sep 9

For nearly a decade, MongoDB provided reliable persistence with one of the most robust storage engines. Yet somehow, the oldest jokes keep persisting, too, so here are some facts:

dev.to/franckpachot...

Resilience of MongoDB's WiredTiger Storage Engine to Disk Failure Compared to PostgreSQL and Oracle

There have been jokes that have contributed to persistent myths about MongoDB's durability. The...

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Franck Pachot @franckpachot.bsky.social · Sep 1

MongoDB is popular, inspiring databases to mimic its features on top of RDBMS. Examining execution plans can provide insight into how things work—such as how to simulate multi-key indexes in a database engine designed for single-key indexes on normalized schemas
dev.to/aws-heroes/d...

DocumentDB: Comparing Emulation Internals with MongoDB

MongoDB is the leading database for document data modeling, with its Atlas service available on AWS,...

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Franck Pachot @franckpachot.bsky.social · Aug 28

If you update a row/document with the same values, is it still an update, or should the database skip the write? SQL vs NoSQL.
dev.to/franckpachot...

Updates to the Same Value: MongoDB Optimization

In MongoDB, when you update a field to the same value it already holds, the database optimizes the...

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Franck Pachot @franckpachot.bsky.social · Aug 25

Embedding a One-to-Many relationship into JSONB to avoid joins, if over 2KB, hides the join, but does not prevent it. Here's how PostgreSQL TOAST works:
dev.to/franckpachot...

Embedding into JSONB still feels like a JOIN for large documents

Think PostgreSQL with JSONB can replace a document database? It’s a tempting idea: embed your related...

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