What are the advantages of scan commands compared to keys *

The advantages of scan command over keys * are: incremental result acquisition to avoid memory problems; use cursor marks to pause and restore processing; support filtering results and narrowing the return range; performance optimization, avoiding full scan at one time; continuous scanning, and real-time update of database changes.

Advantages of scan command

The scan command has the following advantages over keys *:

1. Progressive result acquisition

• The scan command returns the result incrementally, allowing the application to process a small amount of data at a time.
• This is very useful when working with large datasets, as it avoids memory overflow or other performance issues.

2. Use cursor tags

• The scan command uses cursor tags to track where the result is returned.
• This allows the application to pause processing and then resume processing from the last stop.

3. Filter results

• The scan command supports the use of pattern matching to filter the return results.
• This allows the application to retrieve only keys that meet certain criteria.

4. Performance optimization

• The scan command is usually more efficient than keys* because it avoids one-time scans of the entire key space.
• For very large data sets, this can lead to significant performance improvements.

5. Continuous scanning

• The scan command can continuously scan key space and return results when new keys are added or existing keys are updated.
• This is very useful for real-time applications and requires keeping changes in the database up to date.

Specific examples

The following example demonstrates the difference between scan command and keys *:

 <code># 使用keys * 返回所有键keys * # 使用scan 命令以增量方式返回结果scan 0</code>

The scan command will return a small portion of the keys, while keys * will return all keys, which can cause memory issues and delays.

in conclusion

Overall, scan commands are more powerful and efficient than keys* because they provide advantages such as progressive result acquisition, cursor tag support, result filtering, and continuous scanning.

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