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evictable_reader: relax partition key check on reader recreation

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When recreating the underlying reader, the evictable reader validates
that the first partition key it emits is what it expects to be. If the
read stopped at the end of a partition, it expects the first partition
to be a larger one. If the read stopped in the middle of a certain
partition it expects the first partition to be the same it stopped in
the middle of. This latter assumption doesn't hold in all circumstances
however. Namely, the partition it stopped in the middle of might get
compacted away in the time the read was paused, in which case the read
will resume from a greater partition. This perfectly valid cases however
currently triggers the evictable reader's self validation, leading to
the abortion of the read and a scary error to be logged. Relax this
check to accept any partition that is >= compared to the one the read
stopped in the middle of.
This commit is contained in:
Botond Dénes
2021-06-24 16:05:16 +03:00
parent 2740dd2ae4
commit 852bf6befd
2 changed files with 16 additions and 4 deletions
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18
mutation_reader.cc
View File

@@ -1283,13 +1283,25 @@ void evictable_reader::maybe_validate_partition_start(const flat_mutation_reader
// is in range.
if (_last_pkey) {
const auto cmp_res = tri_cmp(*_last_pkey, ps.key());
if (_drop_partition_start) { // should be the same partition
if (_drop_partition_start) { // we expect to continue from the same partition
// We cannot assume the partition we stopped the read at is still alive
// when we recreate the reader. It might have been compacted away in the
// meanwhile, so allow for a larger partition too.
require(
cmp_res == 0,
"{}(): validation failed, expected partition with key equal to _last_pkey {} due to _drop_partition_start being set, but got {}",
cmp_res <= 0,
"{}(): validation failed, expected partition with key larger or equal to _last_pkey {} due to _drop_partition_start being set, but got {}",
__FUNCTION__,
*_last_pkey,
ps.key());
// Reset drop flags and next pos if we are not continuing from the same partition
if (cmp_res < 0) {
// Close previous partition, we are not going to continue it.
push_mutation_fragment(*_schema, _permit, partition_end{});
_drop_partition_start = false;
_drop_static_row = false;
_next_position_in_partition = position_in_partition::for_partition_start();
_trim_range_tombstones = false;
}
} else { // should be a larger partition
require(
cmp_res < 0,

2
test/boost/mutation_reader_test.cc
View File

@@ -3419,7 +3419,7 @@ SEASTAR_THREAD_TEST_CASE(test_evictable_reader_self_validation) {
check_evictable_reader_validation_is_triggered(
"pkey > _last_pkey; pkey ∈ pkrange",
partition_error_prefix,
"",
s.schema(),
permit,
prange,