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76e064e209
This bug has been there at least since MySQL 4.0.9. (Before 4.0.9, the code probably was even more severely broken.) btr_pcur_restore_position(): When cursor restoration fails, before invoking btr_pcur_store_position() move to the previous or next record unless cursor->rel_pos==BTR_PCUR_ON or the record was not a user record. This bug can cause skipped records when btr_pcur_store_position() is called on the last record of a page. A symptom would be record count mismatch in CHECK TABLE, or failure to find a record to delete-mark or update or purge. The following operations should be affected by the bug: * row_search_for_mysql(): SELECT, UPDATE, REPLACE, CHECK TABLE, (almost anything else than INSERT) * foreign key CASCADE operations * row_merge_read_clustered_index(): index creation (since MySQL 5.1 InnoDB Plugin) * multi-threaded purge (after MySQL 5.5): not sure, but it might fail to purge some records Not all callers of btr_pcur_restore_position() should be affected. Anything that asserts or checks that restoration succeeds is unaffected. For example, cursor restoration on the change buffer tree should always succeed, because access is being protected by additional latches. Likewise, rollback, or any code accesses data dictionary tables while holding dict_sys->mutex should be safe. rb:967 approved by Jimmy Yang |
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| btr0btr.c | ||
| btr0cur.c | ||
| btr0pcur.c | ||
| btr0sea.c | ||