SCAN | BestHub

IT Services Circle

Jun 11, 2025 · Databases

How to Count 100 Million Redis Keys Efficiently Without Crashing the Cluster

This article explains why the KEYS * command is dangerous for large Redis deployments and presents several practical alternatives—including SCAN, multithreaded SCAN, cluster‑wide parallel scans, built‑in counters, and real‑time incremental counting—along with code samples, performance comparisons, and guidance on choosing the right solution.

ClusterKey CountingRedis

0 likes · 10 min read

How to Count 100 Million Redis Keys Efficiently Without Crashing the Cluster

Selected Java Interview Questions

Feb 7, 2024 · Databases

How to Use Redis SCAN Instead of KEYS for Safe Large‑Scale Key Enumeration

The article explains why the KEYS command can freeze a Redis instance with millions of keys, analyzes its O(n) blocking behavior, and demonstrates how the incremental SCAN command with cursor, MATCH, and COUNT parameters provides a non‑blocking alternative for retrieving prefixed keys.

RedisSCANbackend

0 likes · 5 min read

How to Use Redis SCAN Instead of KEYS for Safe Large‑Scale Key Enumeration

Architecture Digest

Aug 9, 2023 · Databases

Using Redis SCAN to Safely Enumerate Keys Instead of KEYS

The article explains why using the KEYS command on a large Redis dataset can block the server, introduces the SCAN command as a non‑blocking alternative with cursor‑based iteration, and provides usage examples and best‑practice tips for safely listing prefixed keys.

CacheRedisSCAN

0 likes · 4 min read

Using Redis SCAN to Safely Enumerate Keys Instead of KEYS

Architect's Tech Stack

Apr 13, 2021 · Databases

Safely Accessing Massive Redis Data Without Causing Service Outage

This article explains why using the KEYS command on large Redis keyspaces can crash the service and demonstrates how the SCAN command provides a non‑blocking, incremental way to iterate over massive data safely.

RedisSCANdatabase

0 likes · 4 min read

Safely Accessing Massive Redis Data Without Causing Service Outage

Architect's Tech Stack

Nov 13, 2020 · Databases

How to Safely Scan Large Redis Keyspaces with the SCAN Command

This article explains why using the KEYS command on massive Redis datasets can cause service blockage, analyzes the underlying O(n) traversal cost, and demonstrates how the incremental SCAN command with cursor, MATCH, and COUNT options provides a non‑blocking alternative for efficiently iterating keys.

RedisSCANdatabase

0 likes · 5 min read

How to Safely Scan Large Redis Keyspaces with the SCAN Command

Full-Stack Internet Architecture

Oct 1, 2020 · Databases

Why the Redis KEYS Command Causes Slowdowns and How to Replace It with SCAN

This article explains why using Redis's KEYS command can block other operations, illustrates the underlying single‑threaded execution model, and shows how upgrading shiro‑redis to use the SCAN command avoids performance issues in distributed session management.

RedisSCANSession Management

0 likes · 9 min read

Why the Redis KEYS Command Causes Slowdowns and How to Replace It with SCAN

Selected Java Interview Questions

Jun 3, 2020 · Databases

Using Redis SCAN to Enumerate Keys Safely and Avoid Server Blocking

The article explains why the KEYS command can cripple a Redis instance with millions of keys, analyzes its O(n) blocking behavior, and demonstrates how to use the incremental SCAN command with MATCH and COUNT options to safely iterate key prefixes without affecting performance.

RedisSCANdatabase

0 likes · 5 min read

Using Redis SCAN to Enumerate Keys Safely and Avoid Server Blocking

Architecture Digest

Dec 10, 2019 · Databases

Using Redis SCAN to Safely Enumerate Keys Instead of KEYS

The article explains why using the KEYS command on large Redis datasets can cause service blockage and demonstrates how the SCAN command with MATCH and COUNT options provides a non‑blocking, incremental way to list keys, including syntax and practical examples.

CursorRedisSCAN

0 likes · 5 min read

Big Data Technology Architecture

May 8, 2019 · Databases

Understanding HBase Scan Process and Its Performance Compared to Parquet and Kudu

The article explains why HBase read operations are complex due to its LSM‑Tree storage and multi‑version design, details the step‑by‑step Scan workflow, discusses the reasons for its multi‑request architecture, compares scan performance with Parquet and Kudu, and offers recommendations for large‑scale data scanning.

BigDataHBaseLSM Tree

0 likes · 7 min read

Understanding HBase Scan Process and Its Performance Compared to Parquet and Kudu