3 ms·
> How does that work? Disclaimer: I'm not a Clickhouse user, but I have a bit of experience with Parquet. It looks like the native format is (very briefly) de
by cldellow 4y ago
> How does that work?
Disclaimer: I'm not a Clickhouse user, but I have a bit of experience with Parquet.
It looks like the native format is (very briefly) described here: https://clickhouse.com/docs/en/interfaces/formats/#native https://clickhouse.com/docs/en/interfaces/formats/#native
It looks similar at a high level to Parquet: binary, columnar and has metadata that permits requesting a subset of the data.
Looking at:
> Processed 4.60 thousand rows, 273.86 MB
I'd guess it's chunking the rows into groups of ~4,000.
The OP must have a nice connection if that completed in 0.5 seconds! (Or perhaps the 273.86MB is the uncompressed size after zstd compression, or perhaps there were other parts of the session that caused that chunk to get cached, and it was elided from what was pasted in to HN.)
EDIT: I was curious, so I ran the tool and watched bandwidth on iftop. It uses about ~50MB each time I run the query. From this, I conclude: it does not cache things, the 273.86MB is the uncompressed size, and OP has a much better internet connection than me. :)