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Disable db_stress backward scan with embedded blob SSTs (#14896)

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Summary:
Pull Request resolved: https://github.com/facebook/rocksdb/pull/14896

Replace the earlier mitigation that disabled test_backward_scan when
separate_key_value_in_data_block is set (D109837793). That gate was incorrect:
separate_key_value_in_data_block does not affect value pinning -- it was only
coincidentally correlated with the failing crash-test runs (the crash test
biases it on ~2/3 of the time).

Root cause: embedded blob SSTs are read through EmbeddedBlobResolvingIterator,
which resolves same-file blob references (and wide-column entities with same-file
blob columns) into an iterator-owned buffer. Those resolved values are not
pinnable, but DBIter requires pinned values for backward iteration
(Prev/SeekForPrev), returning NotSupported (surfaced as "Iterator diverged from
control iterator") or hitting the IsValuePinned() assertion in
FindValueForCurrentKeyUsingSeek (db_iter.cc).

Gate test_backward_scan on ingest_external_file_with_embedded_blobs instead.
This is a stress-test mitigation only; the underlying limitation (backward
iteration over unpinnable resolved values) should be fixed separately by making
the resolved value pinnable via the PinnedIteratorsManager.

___

Differential Revision: D110140135

fbshipit-source-id: 5288dab67ab753cbba22806e09fb8fec1e6f5a01
This commit is contained in:
Anand Ananthabhotla
2026-06-29 22:46:48 -07:00
committed by meta-codesync[bot]
parent ffb7788d45
commit 779c7b58d1
1 changed files with 12 additions and 5 deletions
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db_stress_tool/db_stress_tool.cc
+12 -5
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@@ -488,11 +488,18 @@ int db_stress_tool(int argc, char** argv) {
"all be 0 when using compaction filter or inplace update support\n");
exit(1);
}
if (FLAGS_separate_key_value_in_data_block && FLAGS_test_backward_scan) {
// When keys and values are stored separately in data blocks, the
// block-based table iterator cannot pin values. DBIter requires pinned
// values for backward iteration (Prev/SeekForPrev), returning
// NotSupported otherwise. Disable backward scan automatically.
if (FLAGS_ingest_external_file_with_embedded_blobs &&
FLAGS_test_backward_scan) {
// Embedded blob SSTs are read through EmbeddedBlobResolvingIterator, which
// resolves same-file blob references (and wide-column entities with same-
// file blob columns) into an iterator-owned buffer. Such resolved values
// are not pinnable, but DBIter requires pinned values for backward
// iteration (Prev/SeekForPrev) and otherwise returns NotSupported (or hits
// the IsValuePinned() assertion in FindValueForCurrentKeyUsingSeek).
// Disable backward scan automatically.
fprintf(stdout,
"Disabling test_backward_scan because "
"ingest_external_file_with_embedded_blobs is set\n");
FLAGS_test_backward_scan = false;
}
if (FLAGS_test_multi_ops_txns) {