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Avro Demo Description

Last updated: 2024-07-08 19:02:56

    Key Logic Description

    Files in the demo are as described below, with the Java demo as an example.
    consumerDemo-avro-java\\src\\main\\resources\\avro-tools-1.8.2.jar: The tool used to generate Avro protocol code.
    consumerDemo-avro-java\\src\\main\\java\\com\\tencent\\subscribe\\avro: The directory of the Avro tool-generated code.
    consumerDemo-avro-java\\src\\main\\resources\\Record.avsc: The protocol definition file.
    14 structures (also known as schemas in Avro) are defined in Record.avsc. The main data structure is record, which is used to represent a data record in binlog. The record structure is as follows. Other data structures can be viewed in Record.avsc.
    {
    "namespace": "com.tencent.subscribe.avro", // The last schema in `Record.avsc`, with `name` displayed as `Record`.
    "type": "record",
    "name": "Record", // `name` is displayed as `Record`, indicating the format of the data consumed from Kafka.
    "fields": [
    {
    "name": "id", // `id` indicates a globally incremental ID. More record values are explained as follows:
    "type": "long",
    "doc": "unique id of this record in the whole stream"
    },
    {
    "name": "version", // `version` indicates the protocol version.
    "type": "int",
    "doc": "protocol version"
    },
    {
    "name": "messageType", // Message type
    "aliases": [
    "operation"
    ],
    "type": {
    "namespace": "com.tencent.subscribe.avro",
    "name": "MessageType",
    "type": "enum",
    "symbols": [
    "INSERT",
    "UPDATE",
    "DELETE",
    "DDL",
    "BEGIN",
    "COMMIT",
    "HEARTBEAT",
    "CHECKPOINT",
    "ROLLBACK"          
    "STATEMENT",         
     "INIT_DDL",          
      "INIT_INSERT"
    ]
    }
    },
    {
    ......
    },
    }
    Fields in a record are as explained below:
    Field Name in Record
    Description
    id
    The globally incremental ID
    version
    The protocol version, which is v1 currently.
    messageType
    The message type. Enumerated values: INSERT, UPDATE, DELETE, DDL, BEGIN, COMMIT, HEARTBEAT, CHECKPOINT, STATEMENTINIT_DDLINIT_INSERT.
    INIT_DDL: DDL operation on full data; DDL: DDL operation on incremental data; INIT_INSERT: INSERT operation on full data; INSERT: INSERT operation on incremental data.
    fileName
    The name of the binlog file where the current record is located.
    position
    The end offset of the current record in the binlog in the format of End_log_pos@binlog file number. For example, if the current record is in file mysql-bin.000004 and the end offset is 2196, then the value of this parameter will be 2196@4.
    safePosition
    The start offset of the current transaction in the binlog, which is in the same format as described above.
    timestamp
    The time when the data was written to the binlog, which is a UNIX timestamp in seconds.
    gtid
    The current GTID, such as c7c98333-6006-11ed-bfc9-b8cef6e1a231:9.
    transactionId
    The transaction ID, which is generated only for COMMIT events.
    serverId
    The server ID of the source database, which can be viewed by running SHOW VARIABLES LIKE 'server_id'.
    threadId
    The ID of the session that committed the current transaction, which can be viewed by running SHOW processlist;.
    sourceType
    The source database type, which currently can only be MySQL.
    sourceVersion
    The source database version, the value of which is the same as that of select version();
    schemaName
    Database name
    tableName
    Table name
    objectName
    Format: Database name.table name
    columns
    The definitions of columns in the table
    oldColumns
    The data of the row before DML execution. If the message is an INSERT message, the array will be null. There are 12 element types in the array: Integer, Character, Decimal, Float, Timestamp, DateTime, TimestampWithTimeZone, ‍inaryGeometry, TextGeometry, BinaryObject, TextObject, and EmptyObject. For more information, see the demo.
    newColumns
    The data of the row after DML execution. If the message is a DELETE message, the array will be null. There are 12 element types in the array: Integer, Character, Decimal, Float, Timestamp, DateTime, TimestampWithTimeZone, ‍inaryGeometry, TextGeometry, BinaryObject, TextObject, and EmptyObject. For more information, see the demo.
    sql
    The DDL SQL statement.
    executionTime
    The DDL execution duration in seconds.
    heartbeatTimestamp
    The timestamp of the heartbeat message in seconds. This field is present only for heartbeat messages.
    syncedGtid
    The collection of GTIDs parsed by DTS in the format of c7c98333-6006-11ed-bfc9-b8cef6e1a231:1-13.
    fakeGtid
    Whether the current GTID is forged. If gtid_mode is not enabled, DTS will forge a GTID.
    pkNames
    If the table in the source database has a primary key, this parameter will be carried in the DML message; otherwise, it will not be carried.
    readerTimestamp
    The time when DTS processed the current data record, which is a UNIX timestamp in milliseconds.
    tags
    The status_vars in QueryEvent. For more information, see QueryEvent.
    total
    The total number of message segments if the message is segmented. This field is invalid on the current version (version=1) and is reserved for extension.
    index
    The index of message segments if the message is segmented. This field is invalid on the current version (version=1) and is reserved for extension.
    The field describing column attributes in a record is Field, including the following four attributes:
    name: The column name.
    dataTypeNumber: The type of the data recorded in the binlog. For values, see MySQL source code documentation.
    isKey: Whether the current key is the primary key.
    originalType: The type defined in DDL.

    Database field mappings

    The following lists the mappings between database (such as MySQL) field types and data types defined in the Avro protocol.
    Type in MySQL
    Corresponding Type in Avro
    MYSQL_TYPE_NULL
    EmptyObject
    MYSQL_TYPE_INT8
    Integer
    MYSQL_TYPE_INT16
    Integer
    MYSQL_TYPE_INT24
    Integer
    MYSQL_TYPE_INT32
    Integer
    MYSQL_TYPE_INT64
    Integer
    MYSQL_TYPE_BIT
    Integer
    MYSQL_TYPE_YEAR
    DateTime
    MYSQL_TYPE_FLOAT
    Float
    MYSQL_TYPE_DOUBLE
    Float
    MYSQL_TYPE_VARCHAR
    Character
    MYSQL_TYPE_STRING
    Character. If the original type is binary, this type will correspond to BinaryObject.
    MYSQL_TYPE_VAR_STRING
    Character. If the original type is varbinary, this type will correspond to BinaryObject.
    MYSQL_TYPE_TIMESTAMP
    Timestamp
    MYSQL_TYPE_DATE
    DateTime
    MYSQL_TYPE_TIME
    DateTime
    MYSQL_TYPE_DATETIME
    DateTime
    MYSQL_TYPE_TIMESTAMP_NEW
    Timestamp
    MYSQL_TYPE_DATE_NEW
    DateTime
    MYSQL_TYPE_TIME_NEW
    DateTime
    MYSQL_TYPE_DATETIME_NEW
    DateTime
    MYSQL_TYPE_ENUM
    TextObject
    MYSQL_TYPE_SET
    TextObject
    MYSQL_TYPE_DECIMAL
    Decimal
    MYSQL_TYPE_DECIMAL_NEW
    Decimal
    MYSQL_TYPE_JSON
    TextObject
    MYSQL_TYPE_BLOB
    BinaryObject
    MYSQL_TYPE_TINY_BLOB
    BinaryObject
    MYSQL_TYPE_MEDIUM_BLOB
    BinaryObject
    MYSQL_TYPE_LONG_BLOB
    BinaryObject
    MYSQL_TYPE_GEOMETRY
    BinaryObject
    
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