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aec231ba2e
" Currently we have two parallel query paths: * database::query() -> table::query() -> data_query() * mutation::query() The former is used by single partition queries, the latter by range scans, as mutation::query() is used to convert reconcilable_result to query::result (which means it is also used in single partition queries if it triggers read repair). This is a rather unfortunate situation as we have two parallel implementation of the query code, which means they are prone to diverge, and in fact they already have -- more on that later. This patchset aims to remedy this situation by retiring `mutation::query()` and migrating users to an implementation based on the "standard" query path, in other words one using the same building blocks as the `database::query()` path. This means using `compact_mutation` for compacting and `query_result_builder` for result building. These components however were created to work with `flat_mutation_reader`, however introducing a reader into this pipeline would mean that we'd have to make all the related APIs asynchronous, which would cause an insane amount of churn. To avoid this, this patchset adds an API compatible `consume()` method to `mutation`, which can accept a `compact_mutation` instance as-is. This allows an elegant and succinct reimplementation. So far so good. Like mentioned above, the two implementations have diverged in time, or have been different from the start. The difference manifest when calculating digests, more precisely in which tombstones are included in the digest. The retired `mutation::query()` path incorporates only non-purgeable tombstones in the digest. The standard query path however incorporates all tombstones, even those that can be purged. After some scrutiny however this difference proved to be completely theoretical, as the code path where this would matter -- converting reconcilable result to query result -- passes min timestamp as the query time to the compaction, so nothing is compacted and hence the difference has no chance to manifest. This patch-set was motivated by the desire to provide a single solution to #7434, instead of two, one for each path. Tests: unit(release:v2, debug:v2, dev:v3) " * 'unified-query-path/v3' of https://github.com/denesb/scylla: mutation: remove now unused query() and query_compacted() treewide: use query_mutations() instead of mutation::query() mutation_test: test_query_digest: ensure digest is produced consistently mutation_query: introduce query_mutation() mutation_query: to_data_query_result(): migrate to standard query code mutation_query: move to_data_query_result() to mutation_partition.cc mutation: add consume() flat_mutation_reader: move mutation consumer concepts to separate header mutation compactor: query compaction: ignore purgeable tombstones