4 ms·

That is an interesting observation/claim that TiFlash is based on ClickHouse. I’m not sure what benefits ClickHouse has over the ORC/Parquet based Open Source e

That is an interesting observation/claim that TiFlash is based on ClickHouse. I’m not sure what benefits ClickHouse has over the ORC/Parquet based Open Source engines like Presto/Impala. What is emerging in HTAP is two patterns: scale-up like HANA and scale-out like TiDB 4.0. The engine/system in both cases transparently handles the merge between the OLTP delta row store and the OLAP column store (AutoETL) and there is a transparent federated query that is aware of both store types. Does Presto or another scale-out solution transparently perform these two HTAP functions?

qaq 6y ago
"I’m not sure what benefits ClickHouse has over the ORC/Parquet based Open Source engines like Presto/Impala" performance for one
ilovesoup 6y ago
The reason for ClickHouse is simple: it's fast. And we need to have it function like a TiKV coprocessor which support filtering and aggregation mainly and ClickHouse is good at aggregation and filtering. Also it might take more time and dirtier to do seamless / compatible integration to TiDB if Impala or presto on top of MPP layer. But the price we paid is implementing MPP layer by ourselves now. Almost all the data lake based products loss full control over storage system. It makes them very hard to build delta-main engine we need. To make HTAP storage transparent to query layer, TiFlash need a lot more control over storage engine than data lake can provide.