After inserting a page into the wal, we dispose of the modified page.
This is unnecessary as we can simply move new page to the newest
snapshot where this page can be read.
Dirty pages can be deleted in `cacheflush`. Furthermore, there could be
multiple live references in the stack of a cursor so let's allow them to
exist while deleting.
insert() fails if key exists (there shouldn't be two) and panics if
it's different pages, and also fails if it can't make room for the page.
Replaced the limited pop_if_not_dirty() function with make_room_for().
It tries to evict many pages as requested spare capacity. It should come
handy later by resize() and Pager. make_room_for() tries to make room or
fails if it can't evict enough entries.
For make_room_for() I also tried with an all-or-nothing approach, so if
say a query requests a lot more than possible to make room for, it
doesn't evict a bunch of pages from the cache that might be useful. But
implementing this approach got very complicated since it needs to keep
exclusive PageRefs and collecting this caused segfaults. Might be worth
trying again in the future. But beware the rabbit hole.
Updated page cache test logic for new insert rules.
Updated Pager.allocate_page() to handle failure logic but needs further
work. This is to show new cache insert handling. There are many places
to update.
Left comments on callers of pager and page cache needing to update
error handling, for now.
Add error handling and results for insert(), delete(), _delete(),
_detach(), pop_if_not_dirty(), and clear.
Now these functions fail if a page is dirty, locked, or has other
references.
insert() makes room with pop_if_not_dirty() beforehand to handle
cache full and un-evictable, else it would evict this page
silently.
_delete() returns Ok when key is not present in cache and it tries
first to detach the cache entry and clean its page *before*
removing the entry from the map.
detach() checks firstt if it's possible to evict the page and if
there are no other references to the page before taking its
contents.
test_detach_via_delete() and test_detach_via_insert() fixed by
properly checking before and after dropping the page reference.
test_page_cache_fuzz() fixed by reordering and moving reference to
the page into insert.
Other page cache tests fixed to check new function results.
All page cache tests pass.
Error handling and test fixes for Pager and BTree will be added in
a subsequent commit.
Reviewable commit by commit. CI failures are not related.
Adds support for e.g. `select first_name, sum(distinct age),
count(distinct age), avg(distinct age) from users group by 1`
Implementation details:
- Creates an ephemeral index per distinct aggregate, and jumps over the
accumulation step if a duplicate is found
Closes#1507
Various things:
* remove unnecessary debug_validate_cell calls
* Add SortedVec for keys in fuzz tests
* Validate btree's depth in fuzz test every 1K inserts to not overload
test with validations. We add `VALIDATE_BTREE` env variable to enable
validation on every insert in case it is needed.
This PR adds a new function `read_write_payload_with_offset` to support
reading and writing payload data at specific offsets, handling both
local content and overflow pages. This is a port of SQLite's
`accessPayload` function in `btree.c` and will be essential for
supporting incremental blob I/O in the coming PRs.
- Added a state machine called `PayloadOverflowWithOffset` to make the
procedure reentrant.
- Correctly processes both local payload data and payload stored in
overflow pages
Testing:
- Reading and writing to a column with no overflow pages.
- Reading and writing at an offset with overflow pages (spanning 10
pages)
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#1476
