General

What is the relationship between SingleStore Helios and MySQL?

SingleStore Helios is a standalone distributed database that is compatible with MySQL client software.

SingleStore Helios is not a storage engine or other component of MySQL, nor is MySQL a component of SingleStore Helios, and the SingleStore Helios and MySQL servers do not share any code. The SingleStore Helios server includes its own storage engine and SQL-based execution engine built around scalable distributed execution, lock-free data structures, and machine code generation.

Users use MySQL client software to connect to the SingleStore Helios server. SingleStore Helios uses the same wire protocol as MySQL and supports similar SQL syntax as MySQL for compatibility with MySQL client software.

Is SingleStore Helios vulnerable to MySQL server security issues?

No. The SingleStore Helios and MySQL servers are separate database engines which do not share any code, so security issues in the MySQL server are not applicable to SingleStore Helios.

SingleStore Helios implements the MySQL wire protocol in order to provide compatibility with MySQL client software. A part of this compatibility involves reporting a MySQL version number as described above. As a result of this, numerous third-party security scanners that use the reported version number as a vulnerability marker report false positives, as they’re looking at a version number, not at the actual presence of a vulnerability. Our engineering team as well as a third-party security analysis have confirmed that SingleStore Helios is not susceptible to these MySQL vulnerabilities.

Is SingleStore Helios a row-based or column-based store?

SingleStore Helios provides both in-memory row-based and on-disk column-based stores.

The in-memory row store:

• Works best for mixed transactional and analytical workloads

• Provides low latency and highly concurrent reads and writes of individual rows as well as sophisticated analytical SQL queries

• Supports PRIMARY and UNIQUE keys

• Supports geospatial indexes

• Has longer recovery times (as the entire table needs to be loaded into memory)

The on-disk column store:

• Works best for analytical workloads

• Allows tables larger than the amount of available RAM in the workspace

• Uses compression (which lowers disk usage and accelerates replication)

• Provides fast and efficient scans of large datasets

• Provides sorted columnstore indexes

• Is optimized for batch UPDATE and DELETE queries

• Requires more expensive query compilation (as compared to the row store)

How does SingleStore Helios’s in-memory lock-free storage engine work?

SingleStore’s storage engine uses multi-version concurrency control (MVCC) with lock-free skip lists and lock-free hash tables to enable high concurrency and throughput. MVCC allows SELECT queries to run without being blocked by UPDATE queries by maintaining multiple versions of data. The old versions remain accessible to transactions that started before the UPDATE.

Lock-free data structures maximize performance overhead by avoiding traditional locks, while logical locks handle conflicts during concurrent updates. Delayed cleanup ensures that disk space is free once all transactions that depend on the old data are finished. It ensures the safe removal of outdated versions through garbage collection.

What is the advantage of SingleStore Helios over traditional databases like Oracle, SQL Server or MySQL with data in a ramdisk or large buffer pools?

Two common techniques for leveraging large amounts of memory in traditional databases are storing data files on a ramdisk or running a disk-based storage engine with a large buffer pool. For example, MySQL performs much better with InnoDB configured to use a large buffer pool.

While running an existing storage engine like InnoDB in memory can alleviate some of the bottlenecks involved with disk, SingleStore Helios has four distinguishing memory-optimized features that enable it to perform significantly better than disk-based storage engines running in memory:

• SingleStore Helios is a distributed scale-out system. SingleStore Helios scales to thousands of machines on commodity hardware.

• No buffer pool. Traditional databases manage a global buffer pool since they assume that the dataset can’t fit into memory. The buffer pool is a resource shared across all databases and all tables, which creates significant contention.

• Lock-free data structures. SingleStore Helios uses memory-optimized, lock-free skip lists and hash tables as its indexes. Unlike B+ Trees, these data structures are designed from the ground up to be fast in memory.

• Code generation. Lock-free data structures are so fast that dynamic SQL interpretation quickly becomes the limiting factor for query execution. With code generation, SingleStore Helios compiles SQL down to native code for maximum performance.

What is the advantage of SingleStore Helios over other distributed databases?

• Full SQL. SingleStore Helios supports full SQL and transactional semantics.

• Storage pyramid. SingleStore Helios combines row and column store engines tuned for memory and flash storage.

• Scales on commodity hardware. SingleStore Helios does not require exotic hardware and can run on-premises or in the Cloud.

• Enterprise ready. SingleStore Helios supports a large number of enterprise security and manageability features.

What is SingleStore Helios not for?

SingleStore Helios excels at real-time and high throughput query use cases. It is a general purpose database for running both transactional and analytic workloads. However, there are use cases which SingleStore Helios is not designed to run. Some of these are listed below:

• Object store.SingleStore Helios is not designed to be a blob store. It is designed for high value data that is structured or semi-structured and ready to query. SingleStore Helios has open-source connectors for integrating with a variety of object stores, including Amazon S3 and Hadoop File System (HDFS).

• In-process database.SingleStore Helios is not run as a library or in-process with an application. SingleStore Helios is a distributed database which runs in separate processes from the application, and applications connect to SingleStore Helios via a client driver.