tencent cloud

Feedback

Overview

Last updated: 2024-01-19 16:45:30
    The table engine (i.e., table type) determines the following:
    Data storage method and location, and where to write the data to or read the data from
    Supported queries and how they are supported
    Concurrent data access
    Use of indexes (if any)
    Whether multi-threaded requests can be executed
    Data replication parameters

    Engine Types

    MergeTree

    MergeTree engines are the most universal and powerful table engines for high-load tasks. A common feature among them is quick data insertion with subsequent backend data processing. They support data replication (with Replicated* versions of engines), partitioning, and some features not supported by other engines. For more information, see MergeTree.
    Engines in this family:
    MergeTree
    ReplacingMergeTree
    SummingMergeTree
    AggregatingMergeTree
    CollapsingMergeTree
    VersionedCollapsingMergeTree
    GraphiteMergeTree

    Log

    Log engines are lightweight engines with minimum functionality. They are most effective when you need to quickly write many small tables (up to around 1 million rows) and read them later as a whole.
    Engines in this family:
    TinyLog
    StripeLog
    Log

    Integration engines

    Integration engines are for integration with other data storage and processing systems.
    Engines in this family:
    Kafka
    MySQL
    ODBC
    JDBC
    HDFS

    Special engines

    Engines in this family:
    Distributed
    MaterializedView
    Dictionary
    Merge
    File
    Null
    Set
    Join
    URL
    View
    Memory
    Buffer

    Virtual Columns

    Virtual column is an integral table engine attribute that is defined in the engine source code.
    You should not specify virtual columns in the CREATE TABLE query and you cannot see them in SHOW CREATE TABLE and DESCRIBE TABLE query results. Virtual columns are also read-only, so you can't insert data into them.
    To select data from a virtual column, you must specify its name in the SELECT query. SELECT * does not return data from virtual columns.
    If you create a table with a column that has the same name as a table virtual column, the virtual column becomes inaccessible. To avoid such conflicts, virtual column names are usually prefixed with an underscore.
    Contact Us

    Contact our sales team or business advisors to help your business.

    Technical Support

    Open a ticket if you're looking for further assistance. Our Ticket is 7x24 avaliable.

    7x24 Phone Support