Core2

= XTDB 'core2' Research 🧪

Welcome to the XTDB research repository!

NOTE: Core2 now lives in the main XTDB repo, under the https://github.com/xtdb/xtdb/tree/2.x[2.x] branch.

core2 is a bitemporal and dynamic relational database for SQL and Datalog:

• Bitemporal means that all data is accurately versioned as updates are made (system time), and all data exists within a universal domain timeline for representing 'validity'/'effectivity' (application time).
• Dynamic means that no upfront schema needs to be specified before records can be inserted. Complex and nested data is automatically represented using https://arrow.apache.org/[Apache Arrow] types.
• Relational means that the full spectrum of traditional SQL database capabilities is available - including joins, transactions, https://en.wikipedia.org/wiki/Multiset#Applications[bag/multiset] semantics, https://en.wikipedia.org/wiki/Three-valued_logic[three-valued logic], multiple N-ary relations etc.
• SQL means immediate accessibility for a mainstream audience, but also includes an eye to the future with preliminary https://arrow.apache.org/blog/2022/02/16/introducing-arrow-flight-sql/[Flight SQL] driver support.
• https://en.wikipedia.org/wiki/Datalog[Datalog] means a programmer-friendly API for complex relational querying that bypasses SQL's verbose JOINs and https://www.scattered-thoughts.net/writing/against-sql/[compositional challenges].