Support both adjust-to-utc and local-timestamp-micros in Avro Data Type Mappings

[Gezi-lzq]

Feature Request / Improvement

Hi folks,

I would like to understand more about the statement "Avro type annotation adjust-to-utc is an Iceberg convention,” given that Avro already has the Logical Type local-timestamp-micros. Should Iceberg support both the adjust-to-utc and local-timestamp-micros methods simultaneously?

timestamptz:

https://iceberg.apache.org/spec/#avro

{
  "type": "long",
  "logicalType": "timestamp-micros",
  "adjust-to-utc": true
}

and

https://avro.apache.org/docs/1.10.2/spec.html#Decimal

{
  "type": "long",
  "logicalType": "local-timestamp-micros"
}

Reference class:
org.apache.iceberg.avro.SchemaToType#primitive

@rdblue

Query engine

Other

Willingness to contribute

• I can contribute this improvement/feature independently
• I would be willing to contribute this improvement/feature with guidance from the Iceberg community
• I cannot contribute this improvement/feature at this time

[anesterenok]

+1 for this one.
In fact, I do not even understand why Iceberg uses a specified logical type in a way it was never intended to be used.

Avro spec states:

The timestamp-micros logical type represents an instant on the global timeline, independent of a particular time zone or calendar, with a precision of one microsecond.

Any Avro client reading logicalType "timestamp-micros" will expect an Instant, as per Avro spec. If Iceberg wanted to define its own type for local timestamps, they should had used their own logical type, not change the specified one.