QuestDB is an open-source time series database specifically optimized for handling large amounts of time series data. Time series data consists of data points that are timestamped, such as sensor readings, financial data, log data, etc. QuestDB is designed to provide the high performance and scalability required for processing time series data in real-time.

Some of the key features of QuestDB include:

1. Fast Queries: QuestDB utilizes a specialized architecture and optimizations to enable fast queries of time series data, even with very large datasets.

2. Low Storage Footprint: QuestDB is designed to efficiently utilize storage space, particularly for time series data, leading to lower storage costs.

3. SQL Interface: QuestDB provides a SQL interface, allowing users to create and execute queries using a familiar query language.

4. Scalability: QuestDB is horizontally scalable and can handle growing data volumes and workloads.

5. Easy Integration: QuestDB can be easily integrated into existing applications, as it supports a REST API as well as drivers for various programming languages such as Java, Python, Go, and others.

QuestDB is often used in applications that need to capture and analyze large amounts of time series data, such as IoT platforms, financial applications, log analysis tools, and many other use cases that require real-time analytics.

In computer science, particularly in programming, the term "Observable" refers to a concept commonly used in reactive programming. An Observable is a data structure or object representing a sequence of values or events that can occur over time.

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Garbage Collection is a process in many programming languages, including Java, that automatically manages memory in the computer that is no longer needed. When you write a program that allocates memory (for example, creating objects or variables), at some point, you may no longer need that memory.

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In Java, the JVM handles Garbage Collection. It tracks references to objects and identifies when an object is no longer reachable, allowing the memory occupied by that object to be freed. This simplifies programming as developers don't have to manually manage the deallocation of memory that is no longer needed.

The Java Virtual Machine (JVM) is a crucial component of the Java platform. It's a virtual machine that executes Java bytecode. When you write code in Java, you create human-readable code, which is then translated into Java bytecode by the compiler. This bytecode is platform-independent, meaning it can run on any machine that has a JVM, regardless of its operating system.

The JVM is responsible for translating Java bytecode into machine code and executing it on the specific hardware it's running on. It provides an environment for various functionalities such as memory and resource management, garbage collection (cleaning up memory that is no longer needed), and security mechanisms.

The JVM is an essential component that enables Java programs to run on different systems and platforms without requiring the code to be rewritten for each platform.