Implementation of list paging and retrieval in Redis storage

1. Basic operations of Redis list

Before implementing pagination and retrieval, first review the common commands of Redis lists:

• LPUSH key value: Insert an element to the left of the list.

• RPUSH key value: Insert an element to the right of the list.

• LRANGE key start stop: Gets the element (closed interval) of the specified range in the list.

• LLEN key: Get the length of the list.

• LINDEX key index: Gets the element of the specified index in the list.

2. Pagination implementation

Redis's LRANGE command can be used for pagination. Assuming that pageSize data is displayed on each page and the current page is page, the logic of paging is as follows:

• Starting index:start = (page - 1) * pageSize

• End index:end = start + pageSize - 1

Sample code

import ;
import ;

public class RedisListPagination {
    public static void main(String[] args) {
        // Connect to Redis        Jedis jedis = new Jedis("localhost", 6379);

        // List key        String key = "myList";

        // The number of displayed per page        int pageSize = 5;

        // Current page number (starting from 1)        int page = 2;

        // Calculate the start and end index of the page        int start = (page - 1) * pageSize;
        int end = start + pageSize - 1;

        // Use LRANGE to get paginated data        List<String> pageData = (key, start, end);

        // Output pagination results        ("Lesson" + page + " Page Data: " + pageData);

        // Close the connection        ();
    }
}

3. Search and implement

Redis lists themselves do not support direct conditional retrieval (such as WHERE statements in SQL), but they can be retrieved in the following ways:

3.1 Method 1: Client filtering

Use LRANGE to get the entire list or paging data and filter it in the client code.

Sample code

import ;
import ;
import ;

public class RedisListSearch {
    public static void main(String[] args) {
        // Connect to Redis        Jedis jedis = new Jedis("localhost", 6379);

        // List key        String key = "myList";

        // Get the entire list        List<String> allData = (key, 0, -1);

        // Filter on the client (for example: look for elements containing "foo")        List<String> result = ()
                .filter(item -> ("foo"))
                .collect(());

        // Output search results        ("Search results: " + result);

        // Close the connection        ();
    }
}

3.2 Method 2: Use Redis's SCAN command (for large data volumes)

If the list data volume is very large, you can use the SCAN command to gradually traverse the list and filter it.

4. Pagination + Search combination

If you need to support both paging and retrieval, you can filter it on the client first and then paginate the filtered results.

Sample code:

import ;
import ;
import ;

public class RedisListPaginationAndSearch {
    public static void main(String[] args) {
        // Connect to Redis        Jedis jedis = new Jedis("localhost", 6379);

        // List key        String key = "myList";

        // Get the entire list        List<String> allData = (key, 0, -1);

        // Filter on the client (for example: look for elements containing "foo")        List<String> filteredData = ()
                .filter(item -> ("foo"))
                .collect(());

        //Pagination parameters        int pageSize = 5;
        int page = 2;

        // Calculate the start and end index of the page        int start = (page - 1) * pageSize;
        int end = (start + pageSize, ());

        // Get pagination data        List<String> pageData = (start, end);

        // Output pagination results        ("Lesson" + page + " Page Data: " + pageData);

        // Close the connection        ();
    }
}

5. Performance optimization suggestions

• When the data volume is large:

Avoid getting the entire list at once (such as LRANGE key 0 -1), and you can use step-by-step traversal (such as the SCAN command).

If the search conditions are complex, consider using other data structures of Redis (such as Sorted Set) or in combination with external storage (such as Elasticsearch).

• When searching frequently:

List data can be synchronized to other storage that supports efficient retrieval (such as databases or search engines).

• When paging:

If the list data is large, try to avoid frequent paging operations, and you can improve performance by caching paging results.

6. Summary

• Paging: Use the LRANGE command to implement paging.

• Search: Filter on the client, or traverse step by step using the SCAN command.

• Combining pagination and search: Filter first, and then paginate the filtered results.

• Performance optimization: For large data volumes or complex retrieval scenarios, consider using other data structures or external storage.

Through the above methods, the pagination and retrieval functions of Redis lists can be efficiently implemented.

This is the article about the implementation methods of Redis storage list pagination and retrieval. For more related Redis list pagination and retrieval content, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!