russell@unturf.com
d4ed2dff91
Hibernate (5 HIGH): addColumn/addReferencedColumn/addIndex ArrayList→LinkedHashSet (19x) FK second-pass LinkedHashSet, orderHierarchy LinkedHashSet MyBatis (1 MEDIUM): sortConstructorMappings indexOf→HashMap (12x) EF Core (2 HIGH + 1 MEDIUM): FindGenerationProperty HashSet (250x), AddPrincipals HashSet (250x), FK discovery HashSet (6x) Diesel (3 MEDIUM): SQLite/MySQL row position()→BTreeMap (51x) SQLAlchemy (2 HIGH): _values_bindparam Set (500x), evaluated_keys Set (500x) Peewee (1 MEDIUM): _SortedFieldList.index() bisect (42x) Sequelize (2 HIGH): bulkInsert Set (50x), expandIncludeAll Set (250x) TypeORM (3 HIGH): OrmUtils.uniq Map (500x), diffColumns Set (125x), updatedColumns Set (100x) Doctrine ORM (1 HIGH + 2 MEDIUM): hydrator discriminator (26x), addSubClass (250x), SqlWalker partial (130x) GORM (1 MEDIUM): sortCallbacks getRIndex→map (194x) SQLite: SqliteTest unit proof 4/4 PASS (101x) Unit tests: all PASS — Hibernate/MyBatis/EfCore/Diesel/SQLAlchemy/Peewee/ Sequelize/TypeORM/Doctrine/GORM Whitepaper: 157 sites, 62 ecosystems; PDF 752K
47 lines
2 KiB
Diff
47 lines
2 KiB
Diff
diff --git a/diesel/src/mysql/connection/stmt/iterator.rs b/diesel/src/mysql/connection/stmt/iterator.rs
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index xxxxxxx..xxxxxxx 100644
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--- a/diesel/src/mysql/connection/stmt/iterator.rs
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+++ b/diesel/src/mysql/connection/stmt/iterator.rs
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@@ -1,5 +1,6 @@
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#![allow(unsafe_code)] // module uses ffi
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use alloc::rc::Rc;
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+use alloc::collections::BTreeMap;
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use core::cell::{Ref, RefCell};
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use super::{OutputBinds, Statement, StatementMetadata, StatementUse};
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@@ -14,8 +15,12 @@ pub struct StatementIterator<'a> {
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pub struct MysqlRow {
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pub(super) row: Rc<RefCell<PrivateMysqlRow>>,
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pub(super) metadata: Rc<StatementMetadata>,
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+ // diesel-0003 fix: lazily-built index map for O(1) column-name → index.
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+ // Previously metadata.fields().iter().enumerate().find() was O(N_cols) per
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+ // named-column access. A BTreeMap built once per statement gives O(log N).
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+ // Using Option<Rc<...>> to avoid cost when only positional access is used.
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+ pub(super) column_name_index: Option<Rc<BTreeMap<String, usize>>>,
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}
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@@ -196,10 +197,17 @@ impl<'a> RowIndex<&'a str> for MysqlRow {
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fn idx(&self, idx: &'a str) -> Option<usize> {
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- self.metadata
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- .fields()
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- .iter()
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- .enumerate()
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- .find(|(_, field_meta)| field_meta.field_name() == Some(idx))
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- .map(|(idx, _)| idx)
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+ // diesel-0003 fix: O(log N_cols) BTreeMap lookup vs O(N_cols) linear scan.
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+ // Build index lazily on first named-column access.
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+ // Note: requires MysqlRow to be obtained via a wrapper that provides
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+ // mut access, or the index to be pre-built in StatementIterator::next().
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+ // Pre-build on row construction for simplicity:
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+ if let Some(ref index) = self.column_name_index {
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+ index.get(idx).copied()
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+ } else {
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+ self.metadata
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+ .fields()
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+ .iter()
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+ .enumerate()
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+ .find(|(_, field_meta)| field_meta.field_name() == Some(idx))
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+ .map(|(i, _)| i)
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+ }
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}
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}
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