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lock_rec_queue_validate(): Disable a bogus check that

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a transaction that holds a lock on a clustered index record
also holds a lock on the secondary index record.
This commit is contained in:
Marko Mäkelä 2010-04-26 16:10:29 +03:00
commit 4d646bd16e
2 changed files with 46 additions and 2 deletions
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23
storage/innodb_plugin/lock/lock0lock.c
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@ -4710,6 +4710,7 @@ lock_rec_queue_validate(
ut_a(lock_rec_has_expl(LOCK_X | LOCK_REC_NOT_GAP,
block, heap_no, impl_trx));
}
#if 0
} else {
/* The kernel mutex may get released temporarily in the
@ -4720,6 +4721,27 @@ lock_rec_queue_validate(
(fil_space_t::latch), the following check WILL break
latching order and may cause a deadlock of threads. */
/* NOTE: This is a bogus check that would fail in the
following case: Our transaction is updating a
row. After it has updated the clustered index record,
it goes to a secondary index record and finds someone
else holding an explicit S- or X-lock on that
secondary index record, presumably from a locking
read. Our transaction cannot update the secondary
index immediately, but places a waiting X-lock request
on the secondary index record. There is nothing
illegal in this. The assertion is simply too strong. */
/* From the locking point of view, each secondary
index is a separate table. A lock that is held on
secondary index rec does not give any rights to modify
or read the clustered index rec. Therefore, we can
think of the sec index as a separate 'table' from the
clust index 'table'. Conversely, a transaction that
has acquired a lock on and modified a clustered index
record may need to wait for a lock on the
corresponding record in a secondary index. */
impl_trx = lock_sec_rec_some_has_impl_off_kernel(
rec, index, offsets);
@ -4730,6 +4752,7 @@ lock_rec_queue_validate(
ut_a(lock_rec_has_expl(LOCK_X | LOCK_REC_NOT_GAP,
block, heap_no, impl_trx));
}
#endif
}
lock = lock_rec_get_first(block, heap_no);