diff options
Diffstat (limited to 'src/backend/access/gin/README')
| -rw-r--r-- | src/backend/access/gin/README | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README index 421b5b26d5b..30c0867829e 100644 --- a/src/backend/access/gin/README +++ b/src/backend/access/gin/README @@ -304,12 +304,10 @@ the lock on next page has been acquired. The downlink is more tricky. A search descending the tree must release the lock on the parent page before locking the child, or it could deadlock with a concurrent split of the child page; a page split locks the parent, while -already holding a lock on the child page. However, posting trees are only -fully searched from left to right, starting from the leftmost leaf. (The -tree-structure is only needed by insertions, to quickly find the correct -insert location). So as long as we don't delete the leftmost page on each -level, a search can never follow a downlink to page that's about to be -deleted. +already holding a lock on the child page. So, deleted page cannot be reclaimed +immediately. Instead, we have to wait for every transaction, which might wait +to reference this page, to finish. Corresponding processes must observe that +the page is marked deleted and recover accordingly. The previous paragraph's reasoning only applies to searches, and only to posting trees. To protect from inserters following a downlink to a deleted |