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* perf: optimize count(*) Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * fallback to count(1) for temporary table Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * handle alias expr in range plan Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * handle subquery alias Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * rename file Signed-off-by: Ruihang Xia <waynestxia@gmail.com> --------- Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
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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 datafusion::datasource::DefaultTableSource; | ||
use datafusion_common::tree_node::{ | ||
Transformed, TransformedResult, TreeNode, TreeNodeRecursion, TreeNodeVisitor, | ||
}; | ||
use datafusion_common::Result as DataFusionResult; | ||
use datafusion_expr::expr::{AggregateFunction, AggregateFunctionDefinition, WindowFunction}; | ||
use datafusion_expr::utils::COUNT_STAR_EXPANSION; | ||
use datafusion_expr::{col, lit, Expr, LogicalPlan, WindowFunctionDefinition}; | ||
use datafusion_optimizer::utils::NamePreserver; | ||
use datafusion_optimizer::AnalyzerRule; | ||
use table::table::adapter::DfTableProviderAdapter; | ||
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/// A replacement to DataFusion's [`CountWildcardRule`]. This rule | ||
/// would prefer to use TIME INDEX for counting wildcard as it's | ||
/// faster to read comparing to PRIMARY KEYs. | ||
/// | ||
/// [`CountWildcardRule`]: datafusion::optimizer::analyzer::CountWildcardRule | ||
pub struct CountWildcardToTimeIndexRule; | ||
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impl AnalyzerRule for CountWildcardToTimeIndexRule { | ||
fn name(&self) -> &str { | ||
"count_wildcard_to_time_index_rule" | ||
} | ||
|
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fn analyze( | ||
&self, | ||
plan: LogicalPlan, | ||
_config: &datafusion::config::ConfigOptions, | ||
) -> DataFusionResult<LogicalPlan> { | ||
plan.transform_down_with_subqueries(&Self::analyze_internal) | ||
.data() | ||
} | ||
} | ||
|
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impl CountWildcardToTimeIndexRule { | ||
fn analyze_internal(plan: LogicalPlan) -> DataFusionResult<Transformed<LogicalPlan>> { | ||
let name_preserver = NamePreserver::new(&plan); | ||
let new_arg = if let Some(time_index) = Self::try_find_time_index_col(&plan) { | ||
vec![col(time_index)] | ||
} else { | ||
vec![lit(COUNT_STAR_EXPANSION)] | ||
}; | ||
plan.map_expressions(|expr| { | ||
let original_name = name_preserver.save(&expr)?; | ||
let transformed_expr = expr.transform_up_mut(&mut |expr| match expr { | ||
Expr::WindowFunction(mut window_function) | ||
if Self::is_count_star_window_aggregate(&window_function) => | ||
{ | ||
window_function.args.clone_from(&new_arg); | ||
Ok(Transformed::yes(Expr::WindowFunction(window_function))) | ||
} | ||
Expr::AggregateFunction(mut aggregate_function) | ||
if Self::is_count_star_aggregate(&aggregate_function) => | ||
{ | ||
aggregate_function.args.clone_from(&new_arg); | ||
Ok(Transformed::yes(Expr::AggregateFunction( | ||
aggregate_function, | ||
))) | ||
} | ||
_ => Ok(Transformed::no(expr)), | ||
})?; | ||
transformed_expr.map_data(|data| original_name.restore(data)) | ||
}) | ||
} | ||
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fn try_find_time_index_col(plan: &LogicalPlan) -> Option<String> { | ||
let mut finder = TimeIndexFinder::default(); | ||
// Safety: `TimeIndexFinder` won't throw error. | ||
plan.visit(&mut finder).unwrap(); | ||
finder.time_index | ||
} | ||
} | ||
|
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/// Utility functions from the original rule. | ||
impl CountWildcardToTimeIndexRule { | ||
fn is_wildcard(expr: &Expr) -> bool { | ||
matches!(expr, Expr::Wildcard { qualifier: None }) | ||
} | ||
|
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fn is_count_star_aggregate(aggregate_function: &AggregateFunction) -> bool { | ||
matches!( | ||
&aggregate_function.func_def, | ||
AggregateFunctionDefinition::BuiltIn( | ||
datafusion_expr::aggregate_function::AggregateFunction::Count, | ||
) | ||
) && aggregate_function.args.len() == 1 | ||
&& Self::is_wildcard(&aggregate_function.args[0]) | ||
} | ||
|
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fn is_count_star_window_aggregate(window_function: &WindowFunction) -> bool { | ||
matches!( | ||
&window_function.fun, | ||
WindowFunctionDefinition::AggregateFunction( | ||
datafusion_expr::aggregate_function::AggregateFunction::Count, | ||
) | ||
) && window_function.args.len() == 1 | ||
&& Self::is_wildcard(&window_function.args[0]) | ||
} | ||
} | ||
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#[derive(Default)] | ||
struct TimeIndexFinder { | ||
time_index: Option<String>, | ||
table_alias: Option<String>, | ||
} | ||
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impl TreeNodeVisitor for TimeIndexFinder { | ||
type Node = LogicalPlan; | ||
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fn f_down(&mut self, node: &Self::Node) -> DataFusionResult<TreeNodeRecursion> { | ||
if let LogicalPlan::SubqueryAlias(subquery_alias) = node { | ||
self.table_alias = Some(subquery_alias.alias.to_string()); | ||
} | ||
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if let LogicalPlan::TableScan(table_scan) = &node { | ||
if let Some(source) = table_scan | ||
.source | ||
.as_any() | ||
.downcast_ref::<DefaultTableSource>() | ||
{ | ||
if let Some(adapter) = source | ||
.table_provider | ||
.as_any() | ||
.downcast_ref::<DfTableProviderAdapter>() | ||
{ | ||
let table_info = adapter.table().table_info(); | ||
let col_name = table_info.meta.schema.timestamp_column().map(|c| &c.name); | ||
let table_name = self.table_alias.as_ref().unwrap_or(&table_info.name); | ||
self.time_index = col_name.map(|s| format!("{}.{}", table_name, s)); | ||
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return Ok(TreeNodeRecursion::Stop); | ||
} | ||
} | ||
} | ||
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Ok(TreeNodeRecursion::Continue) | ||
} | ||
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fn f_up(&mut self, _node: &Self::Node) -> DataFusionResult<TreeNodeRecursion> { | ||
Ok(TreeNodeRecursion::Stop) | ||
} | ||
} |
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