"
This series introduces PER PARTITION LIMIT to CQL.
Protocol and storage is already capable of applying per-partition limits,
so for nonpaged queries the changes are superficial - a variable is parsed
and passed down.
For paged queries and filtering the situation is a little bit more complicated
due to corner cases: results for one partition can be split over 2 or more pages,
filtering may drop rows, etc. To solve these, another variable is added to paging
state - the number of rows already returned from last served partition.
Note that "last" partition may be stretched over any number of pages, not just the
last one, which is a case especially when considering filtering.
As a result, per-partition-limiting queries are not eligible for page generator
optimization, because they may need to have their results locally filtered
for extraneous rows (e.g. when the next page asks for per-partition limit 5,
but we already received 4 rows from the last partition, so need just 1 more
from last partition key, but 5 from all next ones).
Tests: unit (dev)
Fixes#2202
"
* 'add_per_partition_limit_3' of https://github.com/psarna/scylla:
tests: remove superficial ignore_order from filtering tests
tests: add filtering with per partition key limit test
tests: publish extract_paging_state and count_rows_fetched
tests: fix order of parameters in with_rows_ignore_order
cql3,grammar: add PER PARTITION LIMIT
idl,service: add persistent last partition row count
cql3: prevent page generator usage for per-partition limit
cql3: add checking for previous partition count to filtering
pager: add adjusting per-partition row limit
cql3: obey per partition limit for filtering
cql3: clean up unneeded limit variables
cql3: obey per partition limit for select statement
cql3: add get_per_partition_limit
cql3: add per_partition_limit to CQL statement
6e83457b1b