mirror of
https://github.com/scylladb/scylladb.git
synced 2026-04-21 00:50:35 +00:00
a63b22eec6
Consider the following scenario: 1) let's assume tablet 0 has range [1, 5] (pre merge) 2) tablet merge happens, tablet 0 has now range [1, 10] 3) tablet_sstable_set isn't refreshed, so holds a stale state, thinks tablet 0 still has range [1, 5] 4) during a full scan, forward service will intersect the full range with tablet ranges and consume one tablet at a time 5) replica service is asked to consume range [1, 10] of tablet 0 (post merge) We have two possible outcomes: With cache bypass: 1) cache reader is bypassed 2) sstable reader is created on range [1, 10] 3) unrefreshed tablet_sstable_set holds stale state, but select correctly all sstables intersecting with range [1, 10] With cache: 1) cache reader is created 2) finds partition with token 5 is cached 3) sstable reader is created on range [1, 4] (later would fast forward to range [6, 10]; also belongs to tablet 0) 4) incremental selector consumes the pre-merge sstable spanning range [1, 5] 4.1) since the partitioned_sstable_set pre-merge contains only that sstable, EOS is reached 4.2) since EOS is reached, the fast forward to range [6, 10] is not allowed. So with the set refreshed, sstable set is aligned with tablet ranges, and no premature EOS is signalled, otherwise preventing fast forward to from happening and all data from being properly captured in the read. This change fixes the bug and triggers a mutation source refresh whenever the number of tablets for the table has changed, not only when we have incoming tablets. Additionally, includes a fix for range reads that span more than one tablet, which can happen during split execution. Fixes: https://github.com/scylladb/scylladb/issues/23313 This change needs to be backported to all supported versions which implement tablet merge. - (cherry picked from commitd0329ca370) - (cherry picked from commit1f9f724441) - (cherry picked from commit53df911145) Parent PR: #24287 Closes scylladb/scylladb#24339 * github.com:scylladb/scylladb: replica: Fix range reads spanning sibling tablets test: add reproducer and test for mutation source refresh after merge tablets: trigger mutation source refresh on tablet count change