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simplify

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This commit is contained in:
Jussi Saurio
2025-05-08 16:55:22 +03:00
parent 77f11ba004
commit 87850e5706
1 changed files with 60 additions and 91 deletions
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151
core/translate/optimizer.rs
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@@ -192,46 +192,7 @@ fn join_lhs_tables_to_rhs_table(
* output_cardinality_multiplier)
.ceil() as usize;
// Let's find the best access method and its cost.
// Initialize the best access method to a table scan.
let mut best_access_method = AccessMethod {
// worst case: read all rows of the inner table N times, where N is the number of rows in the outer best_plan
cost: ScanCost {
run_cost: estimate_page_io_cost(
input_cardinality as f64 * ESTIMATED_HARDCODED_ROWS_PER_TABLE as f64,
),
build_cost: Cost(0.0),
},
kind: AccessMethodKind::Scan {
index: None,
iter_dir: if let Some(order_target) = maybe_order_target {
// if the order target 1. has a single column 2. it is the rowid alias of this table 3. the order target column is in descending order, then we should use IterationDirection::Backwards
let rowid_alias_column_no = rhs_table_reference
.columns()
.iter()
.position(|c| c.is_rowid_alias);
let should_use_backwards =
if let Some(rowid_alias_column_no) = rowid_alias_column_no {
order_target.0.len() == 1
&& order_target.0[0].table_no == rhs_table_number
&& order_target.0[0].column_no == rowid_alias_column_no
&& order_target.0[0].order == SortOrder::Desc
} else {
false
};
if should_use_backwards {
IterationDirection::Backwards
} else {
IterationDirection::Forwards
}
} else {
IterationDirection::Forwards
},
},
};
let mut rowid_search = None;
let mut rowid_candidate = None;
for (wi, term) in where_clause.iter().enumerate() {
if let Some(rse) = try_extract_rowid_search_expression(
term,
@@ -243,10 +204,10 @@ fn join_lhs_tables_to_rhs_table(
maybe_order_target,
input_cardinality as f64,
)? {
rowid_search = Some(rse);
rowid_candidate = Some(rse);
}
}
let index_search = try_extract_index_search_from_where_clause(
let index_candidate = try_extract_index_search_from_where_clause(
where_clause,
loop_idx,
rhs_table_number,
@@ -257,57 +218,65 @@ fn join_lhs_tables_to_rhs_table(
input_cardinality as f64,
)?;
match (rowid_search, index_search) {
(Some(rowid_search), None) => {
best_access_method = AccessMethod {
cost: rowid_search.cost,
kind: AccessMethodKind::Search {
search: rowid_search.search.expect("search must exist"),
constraints: rowid_search.constraints,
let best_candidate = match (index_candidate, rowid_candidate) {
(Some(i), Some(r)) => Some(if r.cost.total() < i.cost.total() {
r
} else {
i
}),
(Some(i), None) => Some(i),
(None, r) => r,
};
let best_access_method = match best_candidate {
Some(c) => AccessMethod {
cost: c.cost,
kind: match c.search {
Some(search) => AccessMethodKind::Search {
search,
constraints: c.constraints,
},
};
}
(None, Some(index_search)) => {
best_access_method = AccessMethod {
cost: index_search.cost,
kind: match index_search.search {
Some(search) => AccessMethodKind::Search {
search,
constraints: index_search.constraints,
},
None => AccessMethodKind::Scan {
index: index_search.index,
iter_dir: index_search.iter_dir,
},
None => AccessMethodKind::Scan {
index: c.index,
iter_dir: c.iter_dir,
},
};
}
(Some(rowid_search), Some(index_search)) => {
if rowid_search.cost.total() < index_search.cost.total() {
best_access_method = AccessMethod {
cost: rowid_search.cost,
kind: AccessMethodKind::Search {
search: rowid_search.search.expect("search must exist"),
constraints: rowid_search.constraints,
},
};
} else {
best_access_method = AccessMethod {
cost: index_search.cost,
kind: match index_search.search {
Some(search) => AccessMethodKind::Search {
search,
constraints: index_search.constraints,
},
None => AccessMethodKind::Scan {
index: index_search.index,
iter_dir: index_search.iter_dir,
},
},
};
}
}
(None, None) => {}
},
},
None => AccessMethod {
cost: ScanCost {
run_cost: estimate_page_io_cost(
input_cardinality as f64 * ESTIMATED_HARDCODED_ROWS_PER_TABLE as f64,
),
build_cost: Cost(0.0),
},
kind: AccessMethodKind::Scan {
index: None,
iter_dir: if let Some(order_target) = maybe_order_target {
// if the order target 1. has a single column 2. it is the rowid alias of this table 3. the order target column is in descending order, then we should use IterationDirection::Backwards
let rowid_alias_column_no = rhs_table_reference
.columns()
.iter()
.position(|c| c.is_rowid_alias);
let should_use_backwards =
if let Some(rowid_alias_column_no) = rowid_alias_column_no {
order_target.0.len() == 1
&& order_target.0[0].table_no == rhs_table_number
&& order_target.0[0].column_no == rowid_alias_column_no
&& order_target.0[0].order == SortOrder::Desc
} else {
false
};
if should_use_backwards {
IterationDirection::Backwards
} else {
IterationDirection::Forwards
}
} else {
IterationDirection::Forwards
},
},
},
};
let lhs_cost = lhs.map_or(Cost(0.0), |l| l.cost);