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https://github.com/aljazceru/turso.git
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Merge 'core/translate/optimizer: eliminate unnecessary ORDER BY if result set is already ordered' from Jussi Saurio
Built on top of, and currently targets, #350, _not_ main Closes #365 Examples: ``` limbo> explain select u.first_name, p.name from users u join products p on u.id = p.id order by u.id; addr opcode p1 p2 p3 p4 p5 comment ---- ----------------- ---- ---- ---- ------------- -- ------- 0 Init 0 15 0 0 Start at 15 1 OpenReadAsync 0 2 0 0 table=u, root=2 2 OpenReadAwait 0 0 0 0 3 OpenReadAsync 1 3 0 0 table=p, root=3 4 OpenReadAwait 0 0 0 0 5 RewindAsync 0 0 0 0 6 RewindAwait 0 14 0 0 Rewind table u 7 RowId 0 1 0 0 r[1]=u.rowid 8 SeekRowid 1 1 12 0 if (r[1]!=p.rowid) goto 12 9 Column 0 1 2 0 r[2]=u.first_name 10 Column 1 1 3 0 r[3]=p.name 11 ResultRow 2 2 0 0 output=r[2..3] 12 NextAsync 0 0 0 0 13 NextAwait 0 7 0 0 14 Halt 0 0 0 0 15 Transaction 0 0 0 0 16 Goto 0 1 0 0 ``` ``` limbo> explain select * from users where age > 80 order by age limit 5; addr opcode p1 p2 p3 p4 p5 comment ---- ----------------- ---- ---- ---- ------------- -- ------- 0 Init 0 23 0 0 Start at 23 1 OpenReadAsync 0 2 0 0 table=users, root=2 2 OpenReadAwait 0 0 0 0 3 OpenReadAsync 1 274 0 0 table=age_idx, root=274 4 OpenReadAwait 0 0 0 0 5 Integer 80 1 0 0 r[1]=80 6 SeekGT 1 22 1 0 7 DeferredSeek 1 0 0 0 8 RowId 0 2 0 0 r[2]=users.rowid 9 Column 0 1 3 0 r[3]=users.first_name 10 Column 0 2 4 0 r[4]=users.last_name 11 Column 0 3 5 0 r[5]=users.email 12 Column 0 4 6 0 r[6]=users.phone_number 13 Column 0 5 7 0 r[7]=users.address 14 Column 0 6 8 0 r[8]=users.city 15 Column 0 7 9 0 r[9]=users.state 16 Column 0 8 10 0 r[10]=users.zipcode 17 Column 0 9 11 0 r[11]=users.age 18 ResultRow 2 10 0 0 output=r[2..11] 19 DecrJumpZero 12 22 0 0 if (--r[12]==0) goto 22 20 NextAsync 1 0 0 0 21 NextAwait 1 7 0 0 22 Halt 0 0 0 0 23 Transaction 0 0 0 0 24 Integer 5 12 0 0 r[12]=5 25 Goto 0 1 0 0 ``` Closes #366
This commit is contained in:
Pekka Enberg
@@ -9,12 +9,14 @@ use crate::{
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};
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use super::plan::{
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get_table_ref_bitmask_for_ast_expr, get_table_ref_bitmask_for_operator, Operator, Plan,
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ProjectionColumn, Search,
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get_table_ref_bitmask_for_ast_expr, get_table_ref_bitmask_for_operator, Direction, Operator,
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Plan, ProjectionColumn, Search,
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};
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/**
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* Make a few passes over the plan to optimize it.
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* TODO: these could probably be done in less passes,
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* but having them separate makes them easier to understand
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*/
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pub fn optimize_plan(mut select_plan: Plan) -> Result<(Plan, ExpressionResultCache)> {
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let mut expr_result_cache = ExpressionResultCache::new();
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@@ -39,12 +41,96 @@ pub fn optimize_plan(mut select_plan: Plan) -> Result<(Plan, ExpressionResultCac
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&select_plan.referenced_tables,
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&select_plan.available_indexes,
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)?;
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eliminate_unnecessary_orderby(
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&mut select_plan.root_operator,
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&select_plan.referenced_tables,
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&select_plan.available_indexes,
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)?;
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find_shared_expressions_in_child_operators_and_mark_them_so_that_the_parent_operator_doesnt_recompute_them(&select_plan.root_operator, &mut expr_result_cache);
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Ok((select_plan, expr_result_cache))
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}
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fn _operator_is_already_ordered_by(
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operator: &mut Operator,
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key: &mut ast::Expr,
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available_indexes: &Vec<Rc<Index>>,
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) -> Result<bool> {
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match operator {
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Operator::Scan {
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table,
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table_identifier,
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..
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} => {
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let tuple = (table.clone(), table_identifier.clone());
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Ok(key.is_primary_key_of(&tuple))
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}
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Operator::Search {
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table,
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table_identifier,
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search,
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..
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} => match search {
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Search::PrimaryKeyEq { .. } => {
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let tuple = (table.clone(), table_identifier.clone());
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Ok(key.is_primary_key_of(&tuple))
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}
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Search::PrimaryKeySearch { .. } => {
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let tuple = (table.clone(), table_identifier.clone());
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Ok(key.is_primary_key_of(&tuple))
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}
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Search::IndexSearch { index, .. } => {
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let tuple = (table.clone(), table_identifier.clone());
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let index_idx = key.check_index_scan(&tuple, available_indexes)?;
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let index_is_the_same = index_idx
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.map(|i| Rc::ptr_eq(&available_indexes[i], index))
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.unwrap_or(false);
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Ok(index_is_the_same)
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}
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},
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Operator::Join { left, .. } => {
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_operator_is_already_ordered_by(left, key, available_indexes)
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}
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Operator::Aggregate { source, .. } => {
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_operator_is_already_ordered_by(source, key, available_indexes)
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}
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Operator::Projection { source, .. } => {
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_operator_is_already_ordered_by(source, key, available_indexes)
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}
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_ => Ok(false),
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}
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}
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fn eliminate_unnecessary_orderby(
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operator: &mut Operator,
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referenced_tables: &Vec<(Rc<BTreeTable>, String)>,
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available_indexes: &Vec<Rc<Index>>,
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) -> Result<()> {
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match operator {
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Operator::Order { source, key, .. } => {
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if key.len() != 1 || key.first().unwrap().1 != Direction::Ascending {
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// TODO: handle multiple order by keys and descending order
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return Ok(());
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}
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let already_ordered = _operator_is_already_ordered_by(
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source,
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&mut key.first_mut().unwrap().0,
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available_indexes,
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)?;
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if already_ordered {
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*operator = source.take_ownership();
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}
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Ok(())
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}
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Operator::Limit { source, .. } => {
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eliminate_unnecessary_orderby(source, referenced_tables, available_indexes)?;
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Ok(())
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}
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_ => Ok(()),
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}
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}
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/**
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* Use indexes where possible (currently just primary key lookups)
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* Use indexes where possible
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*/
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fn use_indexes(
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operator: &mut Operator,
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