Project: Explicitly support predicate locks in index AMs besides b-tree
Hi, During this week, I read documentation and source code of gin index to find appropriate places to insert calls to existing functions. Proposal Gin index consists of a Btree index over key values, where each key is an element of some indexed items and each tuple in a leaf page contains either a posting list if the list is small enough or a pointer to posting tree. As gin searches have to go all the way to leaf pages to determine whether there is a match or not, we just need a predicate lock on leaf pages. Also, gin index has a feature called fast update which postpones the insertion of tuples by temporarily storing them into pending list. The pending list is eventually flushed during vacuum. So this creates a problem because even if a scan acquires a page level predicate lock on the pending list, we will not be able to detect r-w conflict because a new insert will just append tuples on the pending list. So, I think if a fast update is enabled, we need a predicate lock on the entire relation. The possible places where we need to insert calls to existing functions are as follows 1. PredicateLockPage() -> entryLoadMoreItems() ->startscanentry() before calling collectMatchBitmap() >scanPostingTree() after acquiring a shared lock on a leaf page 2. CheckForSerializableConflictIn() ->ginentryinsert() ->gininsertitempointers() in case of insertion in a posting tree 3. PredicateLockPageSplit() ->dataBeginPlacetoPageLeaf() after calling dataPlacetoPageLeafSplit() <https://mailtrack.io/> Sent with Mailtrack <https://mailtrack.io/install?source=signature&lang=en&referral=shubhambara...@gmail.com&idSignature=22>
