Improvement: Too much memory consumption on Native format

[kavirajk]

Observed

This is observed by internal observability team when trying to copy system tables from bunch of ClickHouse instances into another ClickHouse instance using Native format.

Expected behaviour

The expected behavior is to be memory efficient, given we move data from one clickhouse into another in native clickhouse format (no need for additional serialization/deserialization)

Details

@RoryCrispin @velom reported this issue few weeks ago. IIRC, they use specific tag of clickhouse-go client

Environment

• clickhouse-go version:
• Interface: ClickHouse API / database/sql compatible driver
• Go version:
• Operating system:
• ClickHouse version:
• Is it a ClickHouse Cloud?
• ClickHouse Server non-default settings, if any:
• CREATE TABLE statements for tables involved:
• Sample data for all these tables, use clickhouse-obfuscator if necessary