getBlob implementation

[AndrewRazumovskiy]

Use case

Download binary files from CH

Describe the solution you'd like

Implement

1. Class - ResultSetImpl
   Method - getBinaryStream(String columnLabel)

2. Class - ResultSetImpl
   Method - getBlob(String columnLabel)

Describe the alternatives you've considered

QuerySettings querySettings = new QuerySettings();
querySettings.setFormat(ClickHouseFormat.RawBLOB);
QueryResponse queryResponse = connection.unwrap(ConnectionImpl.class)
.getClient()
.query("select ...", querySettings)
.get();

Additional context

[chernser]

Good day, @AndrewRazumovskiy !
Thank you for your suggestion!

Would you please describe your use-case?

Thanks!

[AndrewRazumovskiy]

I store raw binary files in CH (png, pdf, txt, excel), and I want to download them as is, in binary mode

[chernser]

@AndrewRazumovskiy

Thank you for the response!
Do you need Blob for some framework?

However method com.clickhouse.jdbc.ResultSetImpl#getBytes(int) or com.clickhouse.jdbc.ResultSetImpl#getBinaryStream(int) is more straightforward option because has less wrapping classes. I assume there is a column of String type that you want to retrieve.

[AndrewRazumovskiy]

ResultSetImpl#getBytes throws "Column is not of array type"
ResultSetImpl#getBinaryStream returns "BinaryStream is not yet supported" (v0.9.1)

[AndrewRazumovskiy]

I tried to use jooq, but in the end fall back to native java

[chernser]

ResultSetImpl#getBytes throws "Column is not of array type"
ResultSetImpl#getBinaryStream returns "BinaryStream is not yet supported" (v0.9.1)
This will be fixed in 0.9.3 (should be ready by end of this month). Here is the issue for that #2263

I tried to use jooq, but in the end fall back to native java
Jooq as I know is built on top of JDBC and it just adds extra layer of abstractions.
We always recommend using clickhouse-java until JDBC is the requirement.