Crate rudb_opt 

The rewrite passes, cardinality estimation, join ordering, predicate transfer and layout adaptation.

Rank 11 in the layer rule. See xtask/layers.toml and spec/18-package-layout.md.

Six passes so far. spec/09-optimizer.md section 9.1 describes a sequence and PASSES is the start of it. Column pruning came first, because it is the pass whose absence is measured in gigabytes: a scan that reads 105 columns to answer a question about three is the whole of the difference on ClickBench, and the Parquet reader has been able to read a subset since M1 with nothing able to tell it which subset.

Modules

columns

Column pruning, which is the scan half of projection pushdown.

distinct

Turning COUNT(DISTINCT x) into a grouping, so that it runs on the machinery grouping already has.

empty

Replacing a subtree that cannot produce a row with a relation that produces none.

estimate

How many rows a node produces, guessed.

explain

What EXPLAIN prints.

filter

Filter pushdown.

fold

Constant folding and the simplifications that fall out of it.

late

Late materialisation: reading the wide columns after the limit rather than before it.

limit

Moving a limit below the projection above it.

nulls

What a predicate says about a row that a join padded with nulls.

pass

What a rewrite is, and what it is given besides the plan.

tables

Which tables an expression reads, and which ones an operator produces.

topn

Turning a limit over a sort into a top N.

Constants

RANK

The crate this rank belongs to, so that the layer check has something to read.

Statics

PASSES

The passes, in the order they run.

UPSTREAM

Every name SET disabled_optimizers accepts, which is every name DuckDB accepts.

Functions

optimize

Rewrites a bound plan into the plan that runs, with every pass on.

optimize_with

Rewrites a bound plan into the plan that runs, skipping the passes the context turned off.