Posts (page 186)
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4 min readTo store JSON data in Redis, you can convert the JSON data into a string using a JSON serialization library (e.g. JSON.stringify in JavaScript) before saving it to Redis. Once converted into a string, you can set the JSON data as a value for a specific key in Redis using the SET command. When retrieving the JSON data from Redis, you can use the GET command to retrieve the string value and then parse it back into JSON using a JSON parsing library (e.g. JSON.parse in JavaScript).
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4 min readTo search by value in Redis, you can use the SCAN command along with the MATCH option to filter by a specific value. This command will scan the keyspace and return keys that match the specified pattern. Additionally, you can use the KEYS command to search for keys that contain a specific value. However, keep in mind that searching by value in Redis can be inefficient as Redis is optimized for fast key-based lookups rather than value-based searches.
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5 min readTo switch from using the hmset() command to the hset() command in Redis, you need to modify your code to set individual fields in a hash rather than set multiple fields at once. The hmset() command allows you to set multiple key-value pairs in a hash, while the hset() command allows you to set a single field-value pair in a hash.
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6 min readTo install a Redis certificate, you need to place it in the directory specified by the Redis configuration file. By default, this would be the "ssl_cert_file" parameter in the Redis configuration file. You can update this parameter with the path to your certificate file. Make sure permissions are set correctly so that Redis can access the certificate file. Once the certificate is installed, you may need to restart the Redis server for the changes to take effect.
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7 min readTo mock Redis session in Python Flask, you can use the redislite package to create an in-memory Redis server for testing purposes. This package allows you to simulate a Redis server without actually having to connect to a real Redis instance. You can then use this simulated Redis server in your tests to interact with the session data.First, you need to install the redislite package by running pip install redislite in your terminal.
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3 min readTo make an asynchronous Redis subscriber call, you can use the redis-py library in Python which provides support for asynchronous programming. You can create a subscriber instance and then use the subscribe method to specify the channel you want to subscribe to. A callback function can be defined to handle messages as they are received. To run the subscriber asynchronously, you can use the asyncio library in Python and run the subscriber in an event loop using the run_forever method.
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6 min readTo import data from Redis to ClickHouse, you can use the ClickHouse's built-in functionality for importing data from various data sources, including Redis. One common approach is to use the ClickHouse Redis Engine to connect to the Redis server and import data into ClickHouse tables. This can be done by setting up a ClickHouse table with the appropriate storage engine, configuring the connection parameters for the Redis server, and executing the necessary SQL statements to import the data.
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7 min readIn Redis, you can add multiple values to a single key by using data structures such as lists or sets.For lists, you can use the LPUSH or RPUSH commands to add values to the beginning or end of the list respectively. For example, you can use the LPUSH command to add multiple values to a list key like this: LPUSH key value1 value2 value3Alternatively, you can use sets which allow you to store unique values.
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5 min readIn order to store multiple sessions in Redis, you can generate a unique session ID for each user session and use this ID as the key to store the session data in Redis. This way, you can easily retrieve the session data by referencing the session ID. Additionally, you can set an expiration time for each session to automatically clear out expired sessions and free up memory in Redis.
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4 min readThe "evicted_keys" value in the output of the Redis INFO command represents the number of keys that have been evicted due to the maxmemory limit being reached. This typically occurs when Redis runs out of memory and needs to remove some keys to free up space for new data. Keeping an eye on the "evicted_keys" count can help monitor memory usage and performance of the Redis database.[rating:ce821fa8-0cbe-48d4-a522-252e94dac366]How to recover data from evicted keys in redis.
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7 min readTo use Python logging with a Redis worker, first import the logging module in your script. Then, set up a logger with the desired level of logging and format. Next, create a Redis connection using the redis-py library and specify the hostname and port of your Redis server.In your worker function, use the logger to log messages at different levels based on the actions performed by the worker. For example, you can use logger.debug() to log debug messages, logger.
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5 min readTo store unique visits in Redis, you can use a Redis set data structure. Each unique visitor can be stored as a member in the set. You can add a visitor to the set using the SADD command and check if a visitor is already in the set using the SISMEMBER command. This way, you can keep track of unique visits without duplicates. You can also use Redis commands like SCARD to get the total number of unique visits stored in the set.