Make GenericRecord and ClickHouseBinaryFormatReader easy to iterate

[abcfy2]

Summary

Add some useful methods to GenericRecord and ClickHouseBinaryFormatReader to make it easy to iterate.

Both GenericRecord and ClickHouseBinaryFormatReader could also get the column size, column names, and the full row values.

Use case:

Records records = client.queryRecords("select * from mytable limit 100").get();
records.forEach(record -> {
    // easy to get column size, then user can use record.getObject(<index>) to get a specified column value
    System.out.println(record.getSize());

    // easy to get column names, then user can use record.getObject(<column_name>) to get a specified column value
    System.out.println(record.getNames());

    // easy to get all row values in kv format
    System.out.println(record.getAll());
});

[chernser]

It should be returned from schema because it may be a virtual columns (for example, when we do so for tuples)

[chernser]

It should come from schema because it may have additional columns.

[chernser]

This cannot be exposed because it is internal records and should not be accessed in such way. I plan to change internal later.

[chernser]

@abcfy2 Thank you for contribution!
However we have com.clickhouse.client.api.data_formats.ClickHouseBinaryFormatReader#getSchema for purpose of getting metadata - it returns a lot more.

[abcfy2]

@chernser Thanks, please check again. 😃 I've never thought to use TableSchema because I find all the records were put into a Map<String, Object> map. I've modified the PR. Please check again. thanks.

[abcfy2]

So the new use case should be:

records.forEach(record -> {
    TableSchema schema = record.getSchema();
    // easy to get column size, then user can use record.getObject(<index>) to get a specified column value
    System.out.println(schema.getColumns().size());

    // easy to get column names, then user can use record.getObject(<column_name>) to get a specified column value
    System.out.println(schema.getColumns().stream().map(ClickHouseColumn::getColumnName).toList());

    // easy to get all row values in kv format
    System.out.println(record.getAll());
});

[chernser]

lets rename it to getValues or asMap.
I would prefer having no default implementation in interfaces because default was designed to not break things when new stream API was introduced in java. I think, that only this case is valid usage of default.

[chernser]

@abcfy2 than you for changing the PR!
I've left 2 comments. I mainly worried about name of the method.

Thanks!

[abcfy2]

No worries @chernser . I've modified PR. Please check again.

Thanks.

[chernser]

@abcfy2 looks good to me!
Thank you!

[abcfy2]

🤨 Some tests failed. But seems it's non of my mistake.