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Franck Pachot @franckpachot.bsky.social · 9d

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 · 10d

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

WiredTigerHS.wt: MongoDB MVCC Durable History Store

Franck Pachot @franckpachot.bsky.social · 12d

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

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 · 13d

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 · 14d

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

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

Reposted by Franck Pachot

Jonathan Lewis @jloracle.bsky.social · 16d

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 · 18d

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...

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

Text Search with MongoDB and PostgreSQL

Franck Pachot @franckpachot.bsky.social · 21d

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

dev.to/franckpachot...

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

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

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Franck Pachot @franckpachot.bsky.social · 23d

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...

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

MongoDB Multikey Indexes and Index Bound Optimization

Franck Pachot @franckpachot.bsky.social · 24d

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...

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

MongoDB Internals: How Collections and Indexes Are Stored in WiredTiger

Franck Pachot @franckpachot.bsky.social · 26d

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...

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

Queryable Encryption - Database Manual - MongoDB Docs

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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/...

www.mongodb.com

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

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...

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

DocumentDB: Comparing Emulation Internals with MongoDB

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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...

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

Updates to the Same Value: MongoDB Optimization

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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...

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

Embedding into JSONB still feels like a JOIN for large documents

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...

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

MongoDB arrays: sort order and comparison

Reposted by Franck Pachot

IntelliJ IDEA, a JetBrains IDE @intellijidea.com · Aug 20

SQL or NoSQL?
@franckpachot.bsky.social explains how to pick the right model for your app in this #IntelliJIDEAConf session 👉 youtu.be/CuA84bJEjDo

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Franck Pachot @franckpachot.bsky.social · Aug 18

New blog post about comparing and sorting arrays in @MongoDB 👇🏼

It's a long story with a short conclusion to help remind it.

dev.to/franckpachot...

Arrays in MongoDB are ordered lists of values, and querying them can be confusing because a field...

Why doesn't Oracle Multi-Value Index optimize .sort() like MongoDB does with its multi-key index?

Franck Pachot @franckpachot.bsky.social · Aug 15

🤓 Some geekery (for my #POUG2025 talk) on index dumps and internals to understand how Oracle Database emulates MongoDB multi-key indexes, and where the limitations come from.

dev.to/franckpachot...

Until recently, Oracle Database offered very limited options for creating inverted indexes, primarily...

Does PostgreSQL support as much "schema flexibility" as MongoDB? Not for indexing!

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Franck Pachot @franckpachot.bsky.social · Aug 13

PostgreSQL makes it easy to fact-check internet myths: read documentation + test with explain analyze 👉🏻 an example: dev.to/mongodb/does... 🤔

Another day, another myth. Someone on Medium claims PostgreSQL offers as much "schema flexibility" as...

MongoDB indexing internals: showRecordId() and hint({$natural:1})

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Franck Pachot @franckpachot.bsky.social · Aug 7

Is MongoDB storing documents like heap tables or index-organized tables?

👉🏻 kind of both, a B+Tree optimized for flexible size documents

dev.to/franckpachot...

You can understand how MongoDB stores documents internally with simple queries that rely on the...

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Franck Pachot @franckpachot.bsky.social · Aug 7

I made it more clear in the article.Thanks for the feedback. It's OCC in WiredTiger, per document, and MongoDB built fail-on-conflict on top, for transactions. Commit should not fail because of data, and could be retried without rollback what was done. Some drivers do that to be resilient to failure