Although SQL and Elasticsearch have different terms for the way the data is organized (and different semantics), these analogies can help those with a relational database background understand Elasticsearch. However, it’s important to recognize that these analogies are not perfect, as there are fundamental differences in how each system stores and manages data. Terminologies and data types [Read More]

When Kafka is running, I mean producer/consumer connected to server and published/subscribed messages normally, what happen when Kafka server is down? Today, to answer this, I try to stop Kafka server (on my local machine): Firstly, the Kafka consumer is still running normally (maybe forever until the server is up), that what I expected. Secondly, the Kafka producer was terminated by these exceptions: Caused by: org.apache.kafka.common.errors.TimeoutException: Topic <> not present in metadata after 60000 ms. The exception was thrown by this config parameter: kafka.max.block.ms is expired, the default is 60000s. Caused by: org.apache.kafka.common.errors.TimeoutException: Expiring 1 record(s) for <>:120010 ms has... [Read More]

In MySQL, if a single index is solely used to weed out rows to be reviewed, I didn’t see much of a difference between a single index and a composite index based on my prior experience. However, I had a personal experience with one last week. I want to share something with you today. [Read More]