Crate datafusion_optimizer 

DataFusion Optimizer

Contains rules for rewriting LogicalPlans

1. Analyzer applies AnalyzerRules to transform LogicalPlans to make the plan valid prior to the rest of the DataFusion optimization process (for example, TypeCoercion).

2. Optimizer applies OptimizerRules to transform LogicalPlans into equivalent, but more efficient plans.

Re-exports

pub use analyzer::Analyzer;

pub use analyzer::AnalyzerRule;

pub use optimizer::ApplyOrder;

pub use optimizer::Optimizer;

pub use optimizer::OptimizerConfig;

pub use optimizer::OptimizerContext;

pub use optimizer::OptimizerRule;

Modules

analyzer

Analyzer and AnalyzerRule

common_subexpr_eliminate

CommonSubexprEliminate to avoid redundant computation of common sub-expressions

decorrelate

PullUpCorrelatedExpr converts correlated subqueries to Joins

decorrelate_lateral_join

DecorrelateLateralJoin decorrelates logical plans produced by lateral joins.

decorrelate_predicate_subquery

DecorrelatePredicateSubquery converts IN/EXISTS subquery predicates to SEMI/ANTI joins

eliminate_cross_join

EliminateCrossJoin converts CROSS JOIN to INNER JOIN if join predicates are available.

eliminate_duplicated_expr

EliminateDuplicatedExpr Removes redundant expressions

eliminate_filter

EliminateFilter replaces where false or where null with an empty relation.

eliminate_group_by_constant

EliminateGroupByConstant removes constant expressions from GROUP BY clause

eliminate_join

EliminateJoin rewrites INNER JOIN with true/null

eliminate_limit

EliminateLimit eliminates LIMIT when possible

eliminate_nested_union

EliminateNestedUnion: flattens nested Union to a single Union

eliminate_one_union

EliminateOneUnion eliminates single element Union

eliminate_outer_join

EliminateOuterJoin converts LEFT/RIGHT/FULL joins to INNER joins

extract_equijoin_predicate

ExtractEquijoinPredicate identifies equality join (equijoin) predicates

filter_null_join_keys

FilterNullJoinKeys adds filters to join inputs when input isn’t nullable

optimize_projections

OptimizeProjections identifies and eliminates unused columns

optimizer

Optimizer and OptimizerRule

propagate_empty_relation

PropagateEmptyRelation eliminates nodes fed by EmptyRelation

push_down_filter

PushDownFilter applies filters as early as possible

push_down_limit

PushDownLimit pushes LIMIT earlier in the query plan

replace_distinct_aggregate

ReplaceDistinctWithAggregate replaces DISTINCT ... with GROUP BY ...

scalar_subquery_to_join

ScalarSubqueryToJoin rewriting scalar subquery filters to JOINs

simplify_expressions

SimplifyExpressions simplifies expressions in the logical plan, ExprSimplifier simplifies individual Exprs.

single_distinct_to_groupby

SingleDistinctToGroupBy replaces AGG(DISTINCT ..) with AGG(..) GROUP BY ..

utils

Utility functions leveraged by the query optimizer rules