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722efb4d8f
The versions collection in data_read_resolver::resolve() is a
std::vector<std::vector<version>>. This contains one entry per unique
partition in the union of all results from each replica.
The vector's size is reserved to the size of partitions in the first
replica's response. Later, new entries are added via `emplace_back()`
for partitions found only in other replica's responses.
This can become really large if there are lot of small partitions, and
especially when there are big differences between the partition set
returned by individual replicas.
With small partitions (e.g. Alternator items with TTL, typically 150-200
bytes each), a single 1 MB read page can carry thousands of partitions,
easily pushing this vector past 2730 entries -- the point at which a
std::vector doubling reallocation exceeds the 128 KB seastar
large-allocation warning threshold:
2 * 2731 * sizeof(std::vector<version>=24) > 131072
Switching to utils::chunked_vector caps every individual allocation at
128 KB by design, regardless of the number of partitions or how much
the replicas diverge. The four internal helper functions that receive
this container (find_short_partitions, get_last_row,
got_incomplete_information_across_partitions, got_incomplete_information)
are updated to accept the new type; their logic is unchanged.
Fixes: SCYLLADB-460
Closes scylladb/scylladb#29325