avro - 逻辑类型的架构

Question

我正在尝试学习 avro 并在架构中有一个问题。
一些文件说

{
      "name": "userid",
       "type" : "string",
       "logicalType" : "uuid"
},

还有人说

{
  "name": "userid",
  "type" : {
    "type" : "string",
    "logicalType" : "uuid"
  }
},

哪一个是对的？或者他们是一样的？
谢谢!

Answer 1

我用 avro tools "random" command 运行了你的模式的变体(以下别名为 avro)。它尝试为模式生成随机值。
仅具有此类型的模式使用嵌套类型语法指定 logicalType被拒绝:

avro random --schema '{ "name": "userid", "type" : { "type": "string", "logicalType" : "uuid" } }' -

[...] No type: {"name":"userid","type":{"type":"string","logicalType":"uuid"}}

但是，它在放置 logicalType 时有效旁边 type :

avro random --schema ' { "type" : "string", "logicalType" : "uuid" }' -

[...] Objavro.schemaL{"type":"string","logicalType":"uuid"}avro.codecdeflate}�j�U�.�\�o���

现在，当我们在记录中使用它时，我们会在放置 logicalType 时收到警告。旁边键入:

avro random --schema '{ "type": "record", "fields": [ { "type" : "string", "logicalType" : "uuid", "name": "f"} ] , "name": "rec"}' -

[...] WARN avro.Schema: Ignored the rec.f.logicalType property ("uuid"). It should probably be nested inside the "type" for the field.Objavro.schema�{"type":"record","name":"rec","fields":[{"name":"f","type":"string","logicalType":"uuid"}]}avro.codecdeflate��w�9�9�n�s�

接受嵌套语法而不发出警告:

avro random --schema '{ "type": "record", "fields": [ { "type" : { "type": "string", "logicalType" : "uuid" } , "name": "f"} ] , "name": "rec"}' -

�w<��qcord","name":"rec","fields":[{"name":"f","type":{"type":"string","logicalType":"uuid"}}]}avro.codecdeflate8��t

此外，如果我们查看数组中的逻辑类型:

avro random --count 1 --schema ' { "type": "array", "items": { "type" : "string", "logicalType" : "uuid" , "name": "f"} , "name": "farr" } ' -

[... random bits]

虽然嵌套版本失败:

avro random --count 1 --schema ' { "type": "array", "items": {"type": { "type" : "string", "logicalType" : "uuid" , "name": "f"} } , "name": "farr" } ' -

[...] No type: {"type":{"type":"string","logicalType":"uuid","name":"f"}}

看来，如果logicalType 是记录中字段的类型，则需要使用嵌套语法。
否则，您需要使用非嵌套语法。