SQL compatibility

    CrateDB supports a set of primitive data types. The following table defines how data types of standard SQL map to CrateDB .

    CREATE TABLE supports additional storage and table parameters for sharding, replication and routing of data, and does not support inheritance.

    ALTER COLUMN and actions are not currently supported (see ).

    The read-only System information and tables have a slightly different schema than specified in standard SQL. They provide schema information and can be queried to get real-time statistical data about the cluster, its nodes, and their shards.

    Standard SQL defines a binary string type, called BLOB or BINARY LARGE OBJECT. With CrateDB, Binary Data is instead stored in separate BLOB Tables (see ) which can be sharded and replicated.

    CrateDB is focused on providing analytical capabilities over supporting traditional transactional use cases, and thus it does not provide transaction control. Every statement commits immediately and is replicated within the cluster.

    However, every row in CrateDB has a version number that is incremented whenever the record is modified. This version number can be used to implement patterns like Optimistic Concurrency Control, which can be used to solve many of the use cases that would otherwise require traditional transactions.

    Unsupported features and functions

    These features of are not supported:

    • Stored procedures

    • Sequences

    • Constraints

      • Unique

      • Foreign key

      • Exclusion constraints

    These functions of standard SQL are either not supported or only partly supported:

    • ENUM support functions

    • IS DISTINCT FROM

    • Network address functions and

    • Mathematical functions

    • Set returning functions

    • Trigger functions

    • XML functions

    Note

    The currently supported and unsupported features in CrateDB are exposed in the table (see sql_features for usage).

    If you have use cases for any missing features, , or dialect improvements, let us know on Github! We are always improving and extending CrateDB and would love to hear your feedback.