[HUDI-8483] Remove unnecessary code

[linliu-code]

Change Logs

When there are log files, the default query type is snapshot query.
When there are no log files, there is no difference between snapshot query and ro queries.

Impact

Simplified code.

Risk level (write none, low medium or high below)

None.

Documentation Update

Describe any necessary documentation update if there is any new feature, config, or user-facing change. If not, put "none".

• The config description must be updated if new configs are added or the default value of the configs are changed
• Any new feature or user-facing change requires updating the Hudi website. Please create a Jira ticket, attach the
  ticket number here and follow the instruction to make
  changes to the website.

Contributor's checklist

• Read through contributor's guide
• Change Logs and Impact were stated clearly
• Adequate tests were added if applicable
• CI passed

[hudi-bot]

CI report:

• 891d09c Azure: PENDING

Bot commands

@hudi-bot supports the following commands:

• @hudi-bot run azure re-run the last Azure build

[yihua]

By default, hoodie.datasource.query.type is set to snapshot, and the new HadoopFSRelation based reader logic in Spark makes sure there's no performance degradation for base file-only cases in MOR, so params.put("hoodie.datasource.query.type", "read_optimized") should not be needed either. Could you point out what errors are thrown if these lines are removed? It would be good to record and understand the errors to make sure there is no other related issue.

[linliu-code]

https://github.com/apache/hudi/blob/master/hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/DefaultSource.scala#L250, which shows there is no default value set.
I did not know if it is safe to rely the default value either.

Meanwhile, do we know how HadoopFSRelation ensure no performance degradation for base file-only cases?

[yihua]

The config itself has the default value defined but as you pointed out it's not honored through the read path with file paths provided (which the clustering execution uses).

val QUERY_TYPE: ConfigProperty[String] = ConfigProperty
    .key("hoodie.datasource.query.type")
    .defaultValue(QUERY_TYPE_SNAPSHOT_OPT_VAL)
    .withAlternatives("hoodie.datasource.view.type")
    .withValidValues(QUERY_TYPE_SNAPSHOT_OPT_VAL, QUERY_TYPE_READ_OPTIMIZED_OPT_VAL, QUERY_TYPE_INCREMENTAL_OPT_VAL)
    .withDocumentation("Whether data needs to be read, in `" + QUERY_TYPE_INCREMENTAL_OPT_VAL + "` mode (new data since an instantTime) " +
      "(or) `" + QUERY_TYPE_READ_OPTIMIZED_OPT_VAL + "` mode (obtain latest view, based on base files) (or) `" + QUERY_TYPE_SNAPSHOT_OPT_VAL + "` mode " +
      "(obtain latest view, by merging base and (if any) log files)")

Also, after checking the code again, when the file paths are provided through "hoodie.datasource.read.paths", the relation-based read path is used (i.e., useNewParquetFileFormat is false). We can keep this for now.

Filed HUDI-8576 as a follow-up.

[yihua]

HUDI-8577 to track default change. We can take this after Hudi 1.0 is released.

[linliu-code]

Anyways, I can reopen this case, and add the default query type.

[linliu-code]

Cool. thanks. then I will close this for now.