# XTDB

> XTDB is an immutable, bitemporal SQL database. Every table is versioned along two axes of time (system time and valid time), so historical and as-of queries need no application-level bookkeeping. It speaks SQL over the Postgres wire protocol and Arrow Flight SQL, and also has its own datalog-style query language, XTQL.

## Documentation Sets

- [Abridged documentation](https://docs.xtdb.com/llms-small.txt): a compact version of the documentation for XTDB, with non-essential content removed
- [Complete documentation](https://docs.xtdb.com/llms-full.txt): the full documentation for XTDB
- [SQL reference](https://docs.xtdb.com/_llms-txt/sql-reference.txt)
- [XTQL reference](https://docs.xtdb.com/_llms-txt/xtql-reference.txt)
- [Operations & configuration](https://docs.xtdb.com/_llms-txt/operations--configuration.txt)
- [Client drivers](https://docs.xtdb.com/_llms-txt/client-drivers.txt)

## Notes

- The complete documentation includes all content from the official documentation
- The content is automatically generated from the same source as the official documentation