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Avoid a multimap when the index is unique #2044

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merged 2 commits into from
Dec 9, 2024
Merged

Avoid a multimap when the index is unique #2044

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96d8caa
remove yielded pointers tracking, it's unused
Centril Dec 6, 2024
fe977aa
don't use multimap for unique indices & correctness fix for create_index
Centril Dec 9, 2024
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26 changes: 23 additions & 3 deletions crates/core/src/db/datastore/locking_tx_datastore/mut_tx.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -399,15 +399,35 @@ impl MutTxId {
_ => unimplemented!(),
};
// Create and build the index.
//
// Ensure adding the index does not cause a unique constraint violation due to
// the existing rows having the same value for some column(s).
let mut insert_index = table.new_index(index.index_id, &columns, is_unique)?;
insert_index.build_from_rows(&columns, table.scan_rows(blob_store))?;
let mut build_from_rows = |table: &Table, bs: &dyn BlobStore| -> Result<()> {
if let Some(violation) = insert_index.build_from_rows(&columns, table.scan_rows(bs))? {
let violation = table
.get_row_ref(bs, violation)
.expect("row came from scanning the table")
.project(&columns)
.expect("`cols` should consist of valid columns for this table");
return Err(IndexError::from(table.build_error_unique(&insert_index, &columns, violation)).into());
}
Ok(())
};
build_from_rows(table, blob_store)?;
// NOTE: Also add all the rows in the already committed table to the index.
//
// FIXME: Is this correct? Index scan iterators (incl. the existing `Locking` versions)
// appear to assume that a table's index refers only to rows within that table,
// and does not handle the case where a `TxState` index refers to `CommittedState` rows.
if let Some(committed_table) = commit_table {
insert_index.build_from_rows(&columns, committed_table.scan_rows(commit_blob_store))?;
//
// TODO(centril): An alternative here is to actually add this index to `CommittedState`,
// pretending that it was already committed, and recording this pretense.
// Then, we can roll that back on a failed tx.
if let Some(commit_table) = commit_table {
build_from_rows(commit_table, commit_blob_store)?;
}

table.indexes.insert(columns.clone(), insert_index);
// Associate `index_id -> (table_id, col_list)` for fast lookup.
idx_map.insert(index_id, (table_id, columns.clone()));
Expand Down
2 changes: 1 addition & 1 deletion crates/core/src/vm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -297,7 +297,7 @@ pub struct IndexSemiJoinLeft<'a, 'c, Rhs: RelOps<'a>> {
pub tx: &'a TxMode<'a>,
}

static_assert_size!(IndexSemiJoinLeft<Box<IterRows<'static>>>, 280);
static_assert_size!(IndexSemiJoinLeft<Box<IterRows<'static>>>, 264);

impl<'a, Rhs: RelOps<'a>> IndexSemiJoinLeft<'a, '_, Rhs> {
fn filter(&self, index_row: &RelValue<'_>) -> bool {
Expand Down
56 changes: 32 additions & 24 deletions crates/table/benches/page_manager.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -721,12 +721,12 @@ impl IndexedRow for Box<str> {
}
}

fn make_table_with_indexes<R: IndexedRow>() -> Table {
fn make_table_with_indexes<R: IndexedRow>(unique: bool) -> Table {
let schema = R::make_schema();
let mut tbl = Table::new(schema.into(), SquashedOffset::COMMITTED_STATE);

let cols = R::indexed_columns();
let idx = tbl.new_index(IndexId::SENTINEL, &cols, false).unwrap();
let idx = tbl.new_index(IndexId::SENTINEL, &cols, unique).unwrap();
tbl.insert_index(&NullBlobStore, cols, idx);

tbl
Expand Down Expand Up @@ -774,22 +774,27 @@ fn clear_all_same<R: IndexedRow>(tbl: &mut Table, val_same: u64) {
}
}

fn bench_id_for_index(name: &str, num_rows: u64, same_ratio: f64, num_same: usize) -> BenchmarkId {
fn bench_id_for_index(name: &str, num_rows: u64, same_ratio: f64, num_same: usize, unique: bool) -> BenchmarkId {
BenchmarkId::new(
name,
format_args!("(rows = {num_rows}, sratio = {same_ratio}, snum = {num_same})"),
format_args!("(rows = {num_rows}, sratio = {same_ratio}, snum = {num_same}, unique = {unique})"),
)
}

fn make_table_with_same_ratio<R: IndexedRow>(
mut make_row: impl FnMut(u64) -> R,
num_rows: u64,
same_ratio: f64,
unique: bool,
) -> (Table, usize, u64) {
let mut tbl = make_table_with_indexes::<R>();
let mut tbl = make_table_with_indexes::<R>(unique);

let num_same = (num_rows as f64 * same_ratio) as usize;
let num_same = num_same.max(1);
let num_same = if unique {
1
} else {
let num_same = (num_rows as f64 * same_ratio) as usize;
num_same.max(1)
};
let num_diff = num_rows / num_same as u64;

for i in 0..num_diff {
Expand All @@ -808,11 +813,11 @@ fn index_insert(c: &mut Criterion) {
same_ratio: f64,
) {
let make_row_move = &mut make_row;
let (tbl, num_same, _) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio);
let (tbl, num_same, _) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio, false);
let mut ctx = (tbl, NullBlobStore);

group.bench_with_input(
bench_id_for_index(name, num_rows, same_ratio, num_same),
bench_id_for_index(name, num_rows, same_ratio, num_same, false),
&num_rows,
|b, &num_rows| {
let pre = |_, (tbl, _): &mut (Table, NullBlobStore)| {
Expand Down Expand Up @@ -859,12 +864,13 @@ fn index_seek(c: &mut Criterion) {
name: &str,
num_rows: u64,
same_ratio: f64,
unique: bool,
) {
let make_row_move = &mut make_row;
let (tbl, num_same, num_diff) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio);
let (tbl, num_same, num_diff) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio, unique);

group.bench_with_input(
bench_id_for_index(name, num_rows, same_ratio, num_same),
bench_id_for_index(name, num_rows, same_ratio, num_same, unique),
&num_diff,
|b, &num_diff| {
let col_to_seek = black_box(R::column_value_from_u64(num_diff / 2));
Expand Down Expand Up @@ -896,25 +902,27 @@ fn index_seek(c: &mut Criterion) {
group: Group<'_, '_>,
name: &str,
same_ratio: f64,
unique: bool,
) {
group.throughput(Throughput::Elements(1));
for num_rows in powers(TABLE_SIZE_POWERS) {
bench_index_seek(&mut make_row, group, name, num_rows, same_ratio);
bench_index_seek(&mut make_row, group, name, num_rows, same_ratio, unique);
}
}

let mut group = c.benchmark_group("index_seek");

bench_many_table_sizes::<u64>(FixedLenRow::from_u64, &mut group, "u64", 0.0);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.00);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.01);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.05);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.10);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.25);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.50);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 1.00);
bench_many_table_sizes::<U32x64>(FixedLenRow::from_u64, &mut group, "U32x64", 0.0);
bench_many_table_sizes::<Box<str>>(|i| i.to_string().into(), &mut group, "String", 0.0);
bench_many_table_sizes::<u64>(FixedLenRow::from_u64, &mut group, "u64", 0.0, false);
bench_many_table_sizes::<u64>(FixedLenRow::from_u64, &mut group, "u64", 0.0, true);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.00, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.01, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.05, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.10, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.25, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 0.50, false);
bench_many_table_sizes::<U32x8>(FixedLenRow::from_u64, &mut group, "U32x8", 1.00, false);
bench_many_table_sizes::<U32x64>(FixedLenRow::from_u64, &mut group, "U32x64", 0.0, false);
bench_many_table_sizes::<Box<str>>(|i| i.to_string().into(), &mut group, "String", 0.0, false);
}

fn index_delete(c: &mut Criterion) {
Expand All @@ -926,10 +934,10 @@ fn index_delete(c: &mut Criterion) {
same_ratio: f64,
) {
let make_row_move = &mut make_row;
let (mut tbl, num_same, _) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio);
let (mut tbl, num_same, _) = make_table_with_same_ratio::<R>(make_row_move, num_rows, same_ratio, false);

group.bench_with_input(
bench_id_for_index(name, num_rows, same_ratio, num_same),
bench_id_for_index(name, num_rows, same_ratio, num_same, false),
&num_rows,
|b, &num_rows| {
let pre = |_, tbl: &mut Table| {
Expand Down
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