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use move_to() in btree_seek_rowid()

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This commit is contained in:
jussisaurio
2024-08-01 18:32:01 +03:00
parent d5ade427c2
commit 02cae50324
1 changed files with 44 additions and 63 deletions
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107
core/storage/btree.rs
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@@ -141,6 +141,50 @@ impl BTreeCursor {
&mut self,
rowid: u64,
) -> Result<CursorResult<(Option<u64>, Option<OwnedRecord>)>> {
self.move_to(rowid)?;
let mem_page = {
let mem_page = self.page.borrow();
let mem_page = mem_page.as_ref().unwrap();
mem_page.clone()
};
let page_idx = mem_page.page_idx;
let page = self.pager.read_page(page_idx)?;
let page = RefCell::borrow(&page);
if page.is_locked() {
return Ok(CursorResult::IO);
}
let page = page.contents.read().unwrap();
let page = page.as_ref().unwrap();
for cell_idx in 0..page.cell_count() {
match &page.cell_get(cell_idx)? {
BTreeCell::TableLeafCell(TableLeafCell {
_rowid: cell_rowid,
_payload: p,
first_overflow_page: _,
}) => {
if *cell_rowid == rowid {
let record = crate::storage::sqlite3_ondisk::read_record(p)?;
return Ok(CursorResult::Ok((Some(*cell_rowid), Some(record))));
}
}
cell_type => {
unreachable!("unexpected cell type: {:?}", cell_type);
}
}
}
Ok(CursorResult::Ok((None, None)))
}
fn move_to_root(&mut self) {
self.page
.replace(Some(Rc::new(MemPage::new(None, self.root_page, 0))));
}
pub fn move_to(&mut self, key: u64) -> Result<CursorResult<()>> {
// For a table with N rows, we can find any row by row id in O(log(N)) time by starting at the root page and following the B-tree pointers.
// B-trees consist of interior pages and leaf pages. Interior pages contain pointers to other pages, while leaf pages contain the actual row data.
//
@@ -164,69 +208,6 @@ impl BTreeCursor {
// 5. We scan the leaf cells in the leaf page until we find the cell whose rowid is equal to the rowid we are looking for.
// This cell contains the actual data we are looking for.
// 6. If we find the cell, we return the record. Otherwise, we return an empty result.
let mut current_page = self.root_page;
loop {
let page = self.pager.read_page(current_page)?;
let page = RefCell::borrow(&page);
if page.is_locked() {
return Ok(CursorResult::IO);
}
let page = page.contents.read().unwrap();
let page = page.as_ref().unwrap();
let mut next_page_found = false;
for cell_idx in 0..page.cell_count() {
match &page.cell_get(cell_idx)? {
BTreeCell::TableInteriorCell(TableInteriorCell {
_left_child_page: lcp,
_rowid: cell_rowid,
}) => {
if rowid <= *cell_rowid {
current_page = *lcp as usize;
next_page_found = true;
break;
}
}
BTreeCell::TableLeafCell(TableLeafCell {
_rowid: cell_rowid,
_payload: p,
first_overflow_page: _,
}) => {
if *cell_rowid == rowid {
let record = crate::storage::sqlite3_ondisk::read_record(p)?;
return Ok(CursorResult::Ok((Some(*cell_rowid), Some(record))));
}
}
BTreeCell::IndexInteriorCell(_) => {
unimplemented!();
}
BTreeCell::IndexLeafCell(_) => {
unimplemented!();
}
}
}
if next_page_found {
continue;
}
match page.rightmost_pointer() {
Some(right_most_pointer) => {
current_page = right_most_pointer as usize;
}
None => {
return Ok(CursorResult::Ok((None, None)));
}
}
}
}
fn move_to_root(&mut self) {
self.page
.replace(Some(Rc::new(MemPage::new(None, self.root_page, 0))));
}
pub fn move_to(&mut self, key: u64) -> Result<CursorResult<()>> {
self.move_to_root();
loop {