Articles by Tag #index
Browse our collection of articles on various topics related to IT technologies. Dive in and explore something new!
Database index tutorial with MYSQL
1. What Is an Index? An index in a database is like the index in a book — it helps you...
Amazon DocumentDB New Query Planner (version 2)
In September 2025, AWS announced it will contribute to the open-source DocumentDB extension for...
Why Java hashmap uses null key and stores it in 0th index?
In Java's HashMap, a null key is stored in bucket 0 because the hashCode() method cannot be invoked...
B-Tree for Equality, Sort, Range (indexing strategies in MongoDB)
When creating an index, you don't need the full details of the queries it will serve, but the...
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Order-preserving or-expansion in MongoDB and $in:[,,] treated as a range skip scan, or exploded to an equality for the ESR rule
I concluded the previous post with a question. We have explored how queries with range and equality...
MongoDB TTL and Disk Storage
In a previous blog post, I explained how MongoDB TTL indexes work and their optimization to avoid...
Indexing for New Use Cases Within the MongoDB Document Model (tutorial)
When designing a schema for MongoDB, it’s crucial to understand your domain access patterns. The...
Index Only Scan on JSON Documents in MongoDB, with covering and multi-key indexes
Storing JSON documents in a SQL database does not make it a document database. The strength of any...
$elemMatch and Multi-Key Indexes
In the previous post, I used the following index on the daily views data, which is an array of...
Comparing Execution Plans: MongoDB vs. Compatible APIs
MongoDB is the standard API for document databases, and some cloud providers have created services...
Document Expiration with TTL Indexes in MongoDB
Without TTL (manual delete job) With TTL (expireAfterSeconds index) Comparison (server metrics and...
Sampling Without Index
I won't create any indexes for this post yet, but I can still filter efficiently to run a query in...
ESR (Equality, Sort, Range) rule applied to YugabyteDB and PostgreSQL indexes
TL;DR: To make developers' lives easier, MongoDB has documented a simple rule for creating an...
$graphLookup (Connect By / Recursive Query)
In this series, I present various access patterns for a specific document model. These patterns are...
Search Index for Reporting
In the first post of this series, I've imported a sample dataset, and I'll show how adding a few...
MongoDB With Search Indexes Queried as Kimball's Star Schema With Facts and Dimensions
Export From SQL to CSV Import to MongoDB Indexing the Star Schema Querying the Star Schema - Star...
No Index for LIKE on JSONB with Array in the Path (GIN limitation)
Here is an example where using PostgreSQL as a document database will quickly fail: indexing. Either...
Google Firestore with MongoDB compatibility - index limitations
In this series, I tested multiple MongoDB emulations on top of SQL databases, and all failed to be...
Introduction to US Stock Market
Stock Market New York Stock Exchange (NYSE): The largest stock exchange in the...
Amazon DocumentDB and multi-key indexing
In previous posts, I discussed the limitations of MongoDB emulations on databases like Oracle and...
Playing With Search: Which Clause(s) Matched?
This article is part of a series. Please see the complete series above. Here's our playground of the...
Postgres: Index Scans
Using an index to help improve query performance is common practice. An index is a structure...
Equality with Multiple Values, Preserving Sort for Pagination
In the previous post, I've created the following index to quickly find the last videos in one...
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B-Tree for Equality, Sort, Range Franck Pachot ・ May 23 ...
Avoiding the Pitfalls of Duplicate Indexes in MySQL
Indexes are fundamental for MySQL optimization, making data retrieval faster and more efficient....
.hint() in MongoDB is different that SQL optimizer hints: they force indexes
MongoDB sits at the crossroads between SQL, where developers can write queries on a logical model...
"The API Is Slow, Fix It!" – What I Learned About `EXPLAIN` and Indexing
During a technical interview, the situation was something like this: “Your manager tells you: the...
PostgreSQL partitioning with desired index names
Introduction A while back, Hetti wrote an article titled Indexing Partitioned Table...
Sort on Array with Multi-Key Index
In the previous post, we discussed how MongoDB indexes retrieve documents ordered by a specific...
Why Doesn't Oracle Multi-Value Index Optimize .sort() Like MongoDB Does With its Multi-Key Index?
Until recently, Oracle Database offered very limited options for creating inverted indexes, primarily...