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Use same move_to() function for tables and indexes

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This commit is contained in:
jussisaurio
2024-10-06 00:51:14 +03:00
parent 37f877109e
commit 1ae8d28669
1 changed files with 24 additions and 66 deletions
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90
core/storage/btree.rs
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@@ -30,6 +30,11 @@ pub enum SeekOp {
GE,
}
pub enum SeekKey<'a> {
TableRowId(u64),
IndexKey(&'a OwnedRecord),
}
#[derive(Debug)]
pub struct MemPage {
parent: Option<Rc<MemPage>>,
@@ -182,7 +187,7 @@ impl BTreeCursor {
key: &OwnedRecord,
op: SeekOp,
) -> Result<CursorResult<(Option<u64>, Option<OwnedRecord>)>> {
match self.index_move_to(key, op.clone())? {
match self.move_to(SeekKey::IndexKey(key), op.clone())? {
CursorResult::Ok(_) => {}
CursorResult::IO => return Ok(CursorResult::IO),
};
@@ -235,7 +240,7 @@ impl BTreeCursor {
rowid: u64,
op: SeekOp,
) -> Result<CursorResult<(Option<u64>, Option<OwnedRecord>)>> {
match self.table_move_to(rowid, op.clone())? {
match self.move_to(SeekKey::TableRowId(rowid), op.clone())? {
CursorResult::Ok(_) => {}
CursorResult::IO => return Ok(CursorResult::IO),
};
@@ -325,7 +330,7 @@ impl BTreeCursor {
}
}
pub fn table_move_to(&mut self, key: u64, cmp: SeekOp) -> Result<CursorResult<()>> {
pub fn move_to<'a>(&mut self, key: SeekKey<'a>, cmp: SeekOp) -> 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.
//
@@ -379,11 +384,14 @@ impl BTreeCursor {
_left_child_page,
_rowid,
}) => {
let SeekKey::TableRowId(rowid_key) = key else {
unreachable!("table seek key should be a rowid");
};
mem_page.advance();
let comparison = match cmp {
SeekOp::GT => key <= *_rowid,
SeekOp::GE => key < *_rowid,
SeekOp::EQ => key < *_rowid,
SeekOp::GT => rowid_key <= *_rowid,
SeekOp::GE => rowid_key < *_rowid,
SeekOp::EQ => rowid_key < *_rowid,
};
if comparison {
let mem_page =
@@ -402,68 +410,20 @@ impl BTreeCursor {
"we don't iterate leaf cells while trying to move to a leaf cell"
);
}
BTreeCell::IndexInteriorCell(_) => {
unimplemented!();
}
BTreeCell::IndexLeafCell(_) => {
unimplemented!();
}
}
}
if !found_cell {
let parent = mem_page.parent.clone();
match page.rightmost_pointer() {
Some(right_most_pointer) => {
let mem_page = MemPage::new(parent, right_most_pointer as usize, 0);
self.page.replace(Some(Rc::new(mem_page)));
continue;
}
None => {
unreachable!("we shall not go back up! The only way is down the slope");
}
}
}
}
}
fn index_move_to(&mut self, key: &OwnedRecord, cmp: SeekOp) -> Result<CursorResult<()>> {
self.move_to_root();
loop {
let mem_page = self.get_mem_page();
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();
if page.is_leaf() {
return Ok(CursorResult::Ok(()));
}
let mut found_cell = false;
for cell_idx in 0..page.cell_count() {
match &page.cell_get(
cell_idx,
self.pager.clone(),
self.max_local(page.page_type()),
self.min_local(page.page_type()),
self.usable_space(),
)? {
BTreeCell::IndexInteriorCell(IndexInteriorCell {
left_child_page,
payload,
..
}) => {
let SeekKey::IndexKey(index_key) = key else {
unreachable!("index seek key should be a record");
};
mem_page.advance();
let record = crate::storage::sqlite3_ondisk::read_record(payload)?;
let comparison = match cmp {
SeekOp::GT => key <= &record,
SeekOp::GE => key < &record,
SeekOp::EQ => key < &record,
SeekOp::GT => index_key <= &record,
SeekOp::GE => index_key < &record,
SeekOp::EQ => index_key < &record,
};
if comparison {
let mem_page =
@@ -473,10 +433,8 @@ impl BTreeCursor {
break;
}
}
_ => {
unreachable!(
"we don't iterate leaf cells while trying to move to a leaf cell"
);
BTreeCell::IndexLeafCell(_) => {
unreachable!("we don't iterate leaf cells while trying to move to a leaf cell");
}
}
}
@@ -1515,7 +1473,7 @@ impl Cursor for BTreeCursor {
_ => unreachable!("btree tables are indexed by integers!"),
};
if !moved_before {
match self.table_move_to(*int_key as u64, SeekOp::EQ)? {
match self.move_to(SeekKey::TableRowId(*int_key as u64), SeekOp::EQ)? {
CursorResult::Ok(_) => {}
CursorResult::IO => return Ok(CursorResult::IO),
};
@@ -1540,7 +1498,7 @@ impl Cursor for BTreeCursor {
OwnedValue::Integer(i) => i,
_ => unreachable!("btree tables are indexed by integers!"),
};
match self.table_move_to(*int_key as u64, SeekOp::EQ)? {
match self.move_to(SeekKey::TableRowId(*int_key as u64), SeekOp::EQ)? {
CursorResult::Ok(_) => {}
CursorResult::IO => return Ok(CursorResult::IO),
};