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Diffstat (limited to 'src/backend/utils/cache/relcache.c')
| -rw-r--r-- | src/backend/utils/cache/relcache.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 90464fd0663..274b48c8951 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -1651,6 +1651,12 @@ RelationClose(Relation relation) * We assume that at the time we are called, we have at least AccessShareLock * on the target index. (Note: in the calls from RelationClearRelation, * this is legitimate because we know the rel has positive refcount.) + * + * If the target index is an index on pg_class or pg_index, we'd better have + * previously gotten at least AccessShareLock on its underlying catalog, + * else we are at risk of deadlock against someone trying to exclusive-lock + * the heap and index in that order. This is ensured in current usage by + * only applying this to indexes being opened or having positive refcount. */ static void RelationReloadIndexInfo(Relation relation) @@ -3611,6 +3617,10 @@ RelationGetIndexPredicate(Relation relation) * Attribute numbers are offset by FirstLowInvalidHeapAttributeNumber so that * we can include system attributes (e.g., OID) in the bitmap representation. * + * Caller had better hold at least RowExclusiveLock on the target relation + * to ensure that it has a stable set of indexes. This also makes it safe + * (deadlock-free) for us to take locks on the relation's indexes. + * * The returned result is palloc'd in the caller's memory context and should * be bms_free'd when not needed anymore. */ |