It's known that reading large cells in reverse cause large allocations.
Source: https://github.com/scylladb/scylladb/issues/11642
The loading is preliminary work for splitting large partitions into
fragments composing a run and then be able to later read such a run
in an efficiency way using the position metadata.
The splitting is not turned on yet, anywhere. Therefore, we can
temporarily disable the loading, as a way to avoid regressions in
stable versions. Large allocations can cause stalls due to foreground
memory eviction kicking in.
The default values for position metadata say that first and last
position include all clustering rows, but they aren't used anywhere
other than by sstable_run to determine if a run is disjoint at
clustering level, but given that no splitting is done yet, it
does not really matter.
Unit tests relying on position metadata were adjusted to enable
the loading, such that they can still pass.
Fixes#11642.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closes#12979
(cherry picked from commit d73ffe7220)
22c1685b3d