VT
And again it's totally unrelated to columns
When I insert a data,
This data will be splited, and then store into different blocks,
what writen to the each block is a column, or a combination of columns?
Size: a a a
2016 November 18
NK
E
as far as i've understood, columns are stored separate from each other, and discussed block settings doesn't relate to storage directly
NK
Block does not store data? Just as an intermediate query?
E
(if, again, i understand everything correctly) each column is a separate entity of storage, and when you store an entity, it is split into columns, and each columns receives new record like
{id: <record id>, value: <record value>}. If that's correct (feel free to correct me if i'm wrong), there is no such term as block on column-level, it's just stream of such values.NK
Thank you very much
RK
@the_real_jkee is it correct to consider such 'blocks' as transactions for insert?
VT
Yes, absolutely
VT
snapshot isolation guarantees works inside this 'blocks'
VT
So if you upload 'max_insert_block_size' data it will be guaranteed to stored as a whole (or you will have an error)
RK
So if you upload 'max_insert_block_size' data it will be guaranteed to stored as a whole (or you will have an error)
thank you :) so feel free to answer everybody clickhouse really has transactions :)
VT
Nope, please do not do that =)
VT
That's the only case where we can say 'it's a transaction'
RK
i guess it's enough for analytical rdbms
VT
RK
think a bit how to describe it better in promo materials -- all guys i know who heard about YCH thinks that it absolutely has no transactions even for bulk insert
VT
ah, okay
VT
thanks for feedback
VT
there is also a question about distributed transaction
VT
should that transaction mean durability in terms of server loss or not