Avro Java API時間戳邏輯類型？

Question

使用Avro Java API，我可以創建一個簡單的記錄模式，如：

    Schema schemaWithTimestamp = SchemaBuilder
            .record("MyRecord").namespace("org.demo")
            .fields()
            .name("timestamp").type().longType().noDefault()
            .endRecord();

如何使用邏輯類型標記架構字段，具體如下： https ： //avro.apache.org/docs/1.8.1/api/java/org/apache/avro/LogicalTypes.TimestampMillis.html

Answer 1

感謝DontPanic：

    Schema timestampMilliType = LogicalTypes.timestampMillis().addToSchema(Schema.create(Schema.Type.LONG));

    Schema schemaWithTimestamp = SchemaBuilder
            .record("MyRecord").namespace("org.demo")
            .fields()
            .name("timestamp_with_logical_type").type(timestampMilliType).noDefault()
            .name("timestamp_no_logical_type").type().longType().noDefault()
            .endRecord();

    System.out.println(schemaWithTimestamp.toString(true));

這導致：

{
  "type" : "record",
  "name" : "MyRecord",
  "namespace" : "org.demo",
  "fields" : [ {
    "name" : "timestamp_with_logical_type",
    "type" : {
      "type" : "long",
      "logicalType" : "timestamp-millis"
    }
  }, {
    "name" : "timestamp_no_logical_type",
    "type" : "long"
  } ]
}

Answer 2

我想你可以手動創建架構：

List<Schema.Field> fields = new ArrayList<>();
Schema timeStampField = Schema.create(Schema.Type.LONG);
fields.add(new Schema.Field("timestamp", LogicalTypes.timestampMillis().addToSchema(timeStampField), null, null));
Schema resultSchema = Schema.createRecord("MyRecord", null, "org.demo", false, fields);
System.out.println(resultSchema);

你的架構：

{"type":"record","name":"MyRecord","namespace":"org.demo","fields":[{"name":"timestamp","type":"long"}]}

帶有timestampMillis的resultSchema：

{"type":"record","name":"MyRecodr","namespace":"org.demo","fields":[{"name":"timestamp","type":{"type":"long","logicalType":"timestamp-millis"}}]}

Answer 3

感謝第一個解決方案，現在可以為nullable logicalType，如：

{ 
"name":"maturityDate",
  "type":["null", {
    "type":"long","logicalType":"timestamp-millis"
    }]
},

我想到以下幾點：

        Schema timestampMilliType = LogicalTypes.timestampMillis().addToSchema(Schema.create(Schema.Type.LONG));

        Schema clientIdentifier = SchemaBuilder.record("ClientIdentifier")
                .namespace("com.baeldung.avro")
                .fields()
                .requiredString("hostName")
                .requiredString("ipAddress")
                .name("maturityDate")
                .type()
                .unionOf()
                .nullType()
                .and()
                .type(timestampMilliType)
                .endUnion()
                .noDefault()
                .endRecord();