partition/multi_dim.rs
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// Copyright 2023 Greptime Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use std::any::Any;
use std::cmp::Ordering;
use std::collections::HashMap;
use datatypes::prelude::Value;
use serde::{Deserialize, Serialize};
use snafu::{ensure, OptionExt};
use store_api::storage::RegionNumber;
use crate::error::{
self, ConjunctExprWithNonExprSnafu, InvalidExprSnafu, Result, UnclosedValueSnafu,
UndefinedColumnSnafu,
};
use crate::expr::{Operand, PartitionExpr, RestrictedOp};
use crate::PartitionRule;
/// Multi-Dimiension partition rule. RFC [here](https://github.com/GreptimeTeam/greptimedb/blob/main/docs/rfcs/2024-02-21-multi-dimension-partition-rule/rfc.md)
///
/// This partition rule is defined by a set of simple expressions on the partition
/// key columns. Compare to RANGE partition, which can be considered as
/// single-dimension rule, this will evaluate expression on each column separately.
#[derive(Debug, Serialize, Deserialize)]
pub struct MultiDimPartitionRule {
/// Allow list of which columns can be used for partitioning.
partition_columns: Vec<String>,
/// Name to index of `partition_columns`. Used for quick lookup.
name_to_index: HashMap<String, usize>,
/// Region number for each partition. This list has the same length as `exprs`
/// (dispiting the default region).
regions: Vec<RegionNumber>,
/// Partition expressions.
exprs: Vec<PartitionExpr>,
}
impl MultiDimPartitionRule {
pub fn try_new(
partition_columns: Vec<String>,
regions: Vec<RegionNumber>,
exprs: Vec<PartitionExpr>,
) -> Result<Self> {
let name_to_index = partition_columns
.iter()
.enumerate()
.map(|(i, name)| (name.clone(), i))
.collect::<HashMap<_, _>>();
let rule = Self {
partition_columns,
name_to_index,
regions,
exprs,
};
let mut checker = RuleChecker::new(&rule);
checker.check()?;
Ok(rule)
}
fn find_region(&self, values: &[Value]) -> Result<RegionNumber> {
ensure!(
values.len() == self.partition_columns.len(),
error::RegionKeysSizeSnafu {
expect: self.partition_columns.len(),
actual: values.len(),
}
);
for (region_index, expr) in self.exprs.iter().enumerate() {
if self.evaluate_expr(expr, values)? {
return Ok(self.regions[region_index]);
}
}
// return the default region number
Ok(0)
}
fn evaluate_expr(&self, expr: &PartitionExpr, values: &[Value]) -> Result<bool> {
match (expr.lhs.as_ref(), expr.rhs.as_ref()) {
(Operand::Column(name), Operand::Value(r)) => {
let index = self.name_to_index.get(name).unwrap();
let l = &values[*index];
Self::perform_op(l, &expr.op, r)
}
(Operand::Value(l), Operand::Column(name)) => {
let index = self.name_to_index.get(name).unwrap();
let r = &values[*index];
Self::perform_op(l, &expr.op, r)
}
(Operand::Expr(lhs), Operand::Expr(rhs)) => {
let lhs = self.evaluate_expr(lhs, values)?;
let rhs = self.evaluate_expr(rhs, values)?;
match expr.op {
RestrictedOp::And => Ok(lhs && rhs),
RestrictedOp::Or => Ok(lhs || rhs),
_ => unreachable!(),
}
}
_ => unreachable!(),
}
}
fn perform_op(lhs: &Value, op: &RestrictedOp, rhs: &Value) -> Result<bool> {
let result = match op {
RestrictedOp::Eq => lhs.eq(rhs),
RestrictedOp::NotEq => lhs.ne(rhs),
RestrictedOp::Lt => lhs.partial_cmp(rhs) == Some(Ordering::Less),
RestrictedOp::LtEq => {
let result = lhs.partial_cmp(rhs);
result == Some(Ordering::Less) || result == Some(Ordering::Equal)
}
RestrictedOp::Gt => lhs.partial_cmp(rhs) == Some(Ordering::Greater),
RestrictedOp::GtEq => {
let result = lhs.partial_cmp(rhs);
result == Some(Ordering::Greater) || result == Some(Ordering::Equal)
}
RestrictedOp::And | RestrictedOp::Or => unreachable!(),
};
Ok(result)
}
}
impl PartitionRule for MultiDimPartitionRule {
fn as_any(&self) -> &dyn Any {
self
}
fn partition_columns(&self) -> Vec<String> {
self.partition_columns.clone()
}
fn find_region(&self, values: &[Value]) -> Result<RegionNumber> {
self.find_region(values)
}
}
/// Helper for [RuleChecker]
type Axis = HashMap<Value, SplitPoint>;
/// Helper for [RuleChecker]
struct SplitPoint {
is_equal: bool,
less_than_counter: isize,
}
/// Check if the rule set covers all the possible values.
///
/// Note this checker have false-negative on duplicated exprs. E.g.:
/// `a != 20`, `a <= 20` and `a > 20`.
///
/// It works on the observation that each projected split point should be included (`is_equal`)
/// and have a balanced `<` and `>` counter.
struct RuleChecker<'a> {
axis: Vec<Axis>,
rule: &'a MultiDimPartitionRule,
}
impl<'a> RuleChecker<'a> {
pub fn new(rule: &'a MultiDimPartitionRule) -> Self {
let mut projections = Vec::with_capacity(rule.partition_columns.len());
projections.resize_with(rule.partition_columns.len(), Default::default);
Self {
axis: projections,
rule,
}
}
pub fn check(&mut self) -> Result<()> {
for expr in &self.rule.exprs {
self.walk_expr(expr)?
}
self.check_axis()
}
#[allow(clippy::mutable_key_type)]
fn walk_expr(&mut self, expr: &PartitionExpr) -> Result<()> {
// recursively check the expr
match expr.op {
RestrictedOp::And | RestrictedOp::Or => {
match (expr.lhs.as_ref(), expr.rhs.as_ref()) {
(Operand::Expr(lhs), Operand::Expr(rhs)) => {
self.walk_expr(lhs)?;
self.walk_expr(rhs)?
}
_ => ConjunctExprWithNonExprSnafu { expr: expr.clone() }.fail()?,
}
return Ok(());
}
// Not conjunction
_ => {}
}
let (col, val) = match (expr.lhs.as_ref(), expr.rhs.as_ref()) {
(Operand::Expr(_), _)
| (_, Operand::Expr(_))
| (Operand::Column(_), Operand::Column(_))
| (Operand::Value(_), Operand::Value(_)) => {
InvalidExprSnafu { expr: expr.clone() }.fail()?
}
(Operand::Column(col), Operand::Value(val))
| (Operand::Value(val), Operand::Column(col)) => (col, val),
};
let col_index =
*self
.rule
.name_to_index
.get(col)
.with_context(|| UndefinedColumnSnafu {
column: col.clone(),
})?;
let axis = &mut self.axis[col_index];
let split_point = axis.entry(val.clone()).or_insert(SplitPoint {
is_equal: false,
less_than_counter: 0,
});
match expr.op {
RestrictedOp::Eq => {
split_point.is_equal = true;
}
RestrictedOp::NotEq => {
// less_than +1 -1
}
RestrictedOp::Lt => {
split_point.less_than_counter += 1;
}
RestrictedOp::LtEq => {
split_point.less_than_counter += 1;
split_point.is_equal = true;
}
RestrictedOp::Gt => {
split_point.less_than_counter -= 1;
}
RestrictedOp::GtEq => {
split_point.less_than_counter -= 1;
split_point.is_equal = true;
}
RestrictedOp::And | RestrictedOp::Or => {
unreachable!("conjunct expr should be handled above")
}
}
Ok(())
}
/// Return if the rule is legal.
fn check_axis(&self) -> Result<()> {
for (col_index, axis) in self.axis.iter().enumerate() {
for (val, split_point) in axis {
if split_point.less_than_counter != 0 || !split_point.is_equal {
UnclosedValueSnafu {
value: format!("{val:?}"),
column: self.rule.partition_columns[col_index].clone(),
}
.fail()?;
}
}
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use std::assert_matches::assert_matches;
use super::*;
use crate::error::{self, Error};
#[test]
fn test_find_region() {
// PARTITION ON COLUMNS (b) (
// b < 'hz',
// b >= 'hz' AND b < 'sh',
// b >= 'sh'
// )
let rule = MultiDimPartitionRule::try_new(
vec!["b".to_string()],
vec![1, 2, 3],
vec![
PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::Lt,
Operand::Value(datatypes::value::Value::String("hz".into())),
),
PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::String("hz".into())),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::Lt,
Operand::Value(datatypes::value::Value::String("sh".into())),
)),
),
PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::String("sh".into())),
),
],
)
.unwrap();
assert_matches!(
rule.find_region(&["foo".into(), 1000_i32.into()]),
Err(error::Error::RegionKeysSize {
expect: 1,
actual: 2,
..
})
);
assert_matches!(rule.find_region(&["foo".into()]), Ok(1));
assert_matches!(rule.find_region(&["bar".into()]), Ok(1));
assert_matches!(rule.find_region(&["hz".into()]), Ok(2));
assert_matches!(rule.find_region(&["hzz".into()]), Ok(2));
assert_matches!(rule.find_region(&["sh".into()]), Ok(3));
assert_matches!(rule.find_region(&["zzzz".into()]), Ok(3));
}
#[test]
fn invalid_expr_case_1() {
// PARTITION ON COLUMNS (b) (
// b <= b >= 'hz' AND b < 'sh',
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1],
vec![PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::String("hz".into())),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::Lt,
Operand::Value(datatypes::value::Value::String("sh".into())),
)),
)),
)],
);
// check rule
assert_matches!(rule.unwrap_err(), Error::InvalidExpr { .. });
}
#[test]
fn invalid_expr_case_2() {
// PARTITION ON COLUMNS (b) (
// b >= 'hz' AND 'sh',
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1],
vec![PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::String("hz".into())),
)),
RestrictedOp::And,
Operand::Value(datatypes::value::Value::String("sh".into())),
)],
);
// check rule
assert_matches!(rule.unwrap_err(), Error::ConjunctExprWithNonExpr { .. });
}
/// ```ignore
/// │ │
/// │ │
/// ─────────┼──────────┼────────────► b
/// │ │
/// │ │
/// b <= h b >= s
/// ```
#[test]
fn empty_expr_case_1() {
// PARTITION ON COLUMNS (b) (
// b <= 'h',
// b >= 's'
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1, 2],
vec![
PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::String("h".into())),
),
PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::String("s".into())),
),
],
);
// check rule
assert_matches!(rule.unwrap_err(), Error::UnclosedValue { .. });
}
/// ```
/// a
/// ▲
/// │ ‖
/// │ ‖
/// 200 │ ┌─────────┤
/// │ │ │
/// │ │ │
/// │ │ │
/// 100 │ ======┴─────────┘
/// │
/// └──────────────────────────►b
/// 10 20
/// ```
#[test]
fn empty_expr_case_2() {
// PARTITION ON COLUMNS (b) (
// a >= 100 AND b <= 10 OR a > 100 AND a <= 200 AND b <= 10 OR a >= 200 AND b > 10 AND b <= 20 OR a > 200 AND b <= 20
// a < 100 AND b <= 20 OR a >= 100 AND b > 20
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1, 2],
vec![
PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
// a >= 100 AND b <= 10
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::Int64(100)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(10)),
)),
)),
RestrictedOp::Or,
// a > 100 AND a <= 200 AND b <= 10
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::Gt,
Operand::Value(datatypes::value::Value::Int64(100)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(200)),
)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(10)),
)),
)),
)),
RestrictedOp::Or,
// a >= 200 AND b > 10 AND b <= 20
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::Int64(200)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::Gt,
Operand::Value(datatypes::value::Value::Int64(10)),
)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
)),
)),
)),
RestrictedOp::Or,
// a > 200 AND b <= 20
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::Gt,
Operand::Value(datatypes::value::Value::Int64(200)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
)),
)),
),
PartitionExpr::new(
// a < 100 AND b <= 20
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::Lt,
Operand::Value(datatypes::value::Value::Int64(100)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
)),
)),
RestrictedOp::Or,
// a >= 100 AND b > 20
Operand::Expr(PartitionExpr::new(
Operand::Expr(PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::Int64(100)),
)),
RestrictedOp::And,
Operand::Expr(PartitionExpr::new(
Operand::Column("b".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
)),
)),
),
],
);
// check rule
assert_matches!(rule.unwrap_err(), Error::UnclosedValue { .. });
}
#[test]
fn duplicate_expr_case_1() {
// PARTITION ON COLUMNS (a) (
// a <= 20,
// a >= 10
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1, 2],
vec![
PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
),
PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::GtEq,
Operand::Value(datatypes::value::Value::Int64(10)),
),
],
);
// check rule
assert_matches!(rule.unwrap_err(), Error::UnclosedValue { .. });
}
#[test]
#[ignore = "checker cannot detect this kind of duplicate for now"]
fn duplicate_expr_case_2() {
// PARTITION ON COLUMNS (a) (
// a != 20,
// a <= 20,
// a > 20,
// )
let rule = MultiDimPartitionRule::try_new(
vec!["a".to_string(), "b".to_string()],
vec![1, 2],
vec![
PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::NotEq,
Operand::Value(datatypes::value::Value::Int64(20)),
),
PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::LtEq,
Operand::Value(datatypes::value::Value::Int64(20)),
),
PartitionExpr::new(
Operand::Column("a".to_string()),
RestrictedOp::Gt,
Operand::Value(datatypes::value::Value::Int64(20)),
),
],
);
// check rule
assert!(rule.is_err());
}
}