ClickHouse reads table data in blocks of 'max_block_size' rows. Due to
filtering, aggregation, etc., result blocks are typically much smaller
than 'max_block_size' but there are also cases where they are much
bigger. Setting 'query_cache_squash_partial_results' (enabled by
default) now controls if result blocks are squashed (if they are tiny)
or split (if they are large) into blocks of 'max_block_size' size before
insertion into the query result cache. This reduces performance of
writes into the query cache but improves compressability of cache
entries and provides more natural block granularity when query results
are later served from the query cache.
Entries in the query cache are now also compressed by default. This
reduces the overall memory consumption at the cost of slower writes into
/ reads from the query cache. To disable compression, use setting
'query_cache_compress_entries'.
