Implement expression evaluation in RETURN projections by cyrusknopf · Pull Request #407 · turing-db/turingdb

cyrusknopf · 2026-02-09T16:35:43Z

Implements #359

Overview:

Adds unnamed variable declarations for binary expressions
Updates CountProcessor to use new ColumnOperatorDispatcher
Implements ExprEvalProcessor to evaluate expressions and store the results in the output dataframe
Modifies ExprProgramGenerator with more support for unary expressions
Adds support in PipelineGenerator for the new ExprEvalProcessor
Adds evaluation logic for functions with expressions-as-arguments

cyrusknopf · 2026-02-16T13:59:37Z

test/query/pipeline/processors/HashJoinProcessorTest.cpp


    const auto& expectedFirstCol = std::views::iota(1000, 2000);
-    const auto& expectedSecondCol = std::views::iota(2000, 300);
+    const auto& expectedSecondCol = std::views::iota(2000, 3000);


Fixes a bug which was caught by gcc15

Do you have the bug logs? I'm curious! If not don't worry about it

I can't seem to repro now haha. But it was a static_assert failing because the start of the range (2000) was greater than the end of the range (300)

rjb32 · 2026-02-17T15:34:15Z

query/analyzer/ExprAnalyzer.cpp

+
+    // Create a variable declaration for the binary expression so that it can be retrieved
+    // later (for projection or in an expression / filter), e.g. RETURN COUNT(5 + 5)
+    expr->setExprVarDecl(_ctxt->createUnnamedVariable(_ast, expr->getType()));


It would look better if you created a temporary for the variable declaration pointer instead of a nested call line

rjb32 · 2026-02-17T15:34:58Z

query/pipeline/processors/CountProcessor.cpp

 }

-void CountProcessor::prepare(ExecutionContext* ctxt) {
+void CountProcessor::prepare(ExecutionContext* /*ctxt*/) {


Just keep ctxt that's ok

rjb32 · 2026-02-17T15:36:46Z

query/pipeline/processors/CountProcessor.cpp


+    // @ref _col is nullptr in the case of a COUNT(*), which in Cypher means "count the
+    // number of rows in the output". Unlike a COUNT(n.name), COUNT(*) also includes
+    // null-valued rows


It's a bit weird that there is nothing in that sense in the prepare function which gives the impression that _col will always be non-null

rjb32 · 2026-02-17T15:37:51Z

query/pipeline/processors/CountProcessor.cpp

 inline constexpr bool is_template_t = is_template<T, Template>::value;

+/// Functor to pass to column dispatcher to count rows
+struct Counter {


Do you really need it to be a struct? It is almost always better to have a class. Especially if you actually don't access the public members

Made Counter a class

rjb32 · 2026-02-17T15:38:35Z

query/pipeline/processors/CountProcessor.cpp

+
+        Counter counter(localCount);
+        using Types = OutputtedTypes;
+        using CountDispatch =


It looks very compact otherwise it is much better

rjb32 · 2026-02-17T15:39:18Z

query/pipeline/processors/CountProcessor.h


+// Methods such as @ref Dataframe::getLogicalRowCount return a size_t; ensure types are
+// compatible.
+static_assert(std::numeric_limits<size_t>::max()


Should we rather put this static_assert inside the CountProcessor class?

What is the benefit of putting it inside the class?

There is none really besides an esthetic one, it avoids having a statement at global scope in principle when it is about a type alias defined with using inside the class

Moved the static_assert into the class

rjb32 · 2026-02-17T15:46:14Z

query/plan/PipelineGenerator.cpp

+                const ColumnTag tag = findColIt->second;

                items.push_back({tag, *name});



Remove blank line here

query/pipeline/processors/CountProcessor.cpp

query/pipeline/processors/ExprEvalProcessor.h

github-actions · 2026-02-18T15:38:48Z

Claude Code Review

Violations found (click to expand)

File	Line	Rule	Violation
storage/columns/UnaryPredicates.h	`static void apply(ColumnConst<T>* res, const ColumnConst<T>* arg) requires OptionalPredicate<Op, T>` + next line `{`	CODING_STYLE.md — Brackets: "Constructors are the only place where the opening bracket must be on the next line"; methods have `{` on the same line	Opening brace `{` is on its own line for a static method; it should be on the same line as the `requires` clause.
storage/columns/UnaryPredicates.h	`static void apply(ColumnVector<T>* res, const ColumnVector<T>* arg) requires(...)` + next line `{`	CODING_STYLE.md — Brackets: "Constructors are the only place where the opening bracket must be on the next line"; methods have `{` on the same line	Opening brace `{` is on its own line for a static method; it should be on the same line as the `requires` clause.

Checked against CODING_STYLE.md and REVIEW.md.

@rjb32 false positive, as per our discussion about "requires" clauses after function parameter lists

cyrusknopf mentioned this pull request Feb 9, 2026

Implement arbitrary expression evaluation in RETURN projections #360

Closed

cyrusknopf self-assigned this Feb 9, 2026

cyrusknopf force-pushed the expr/return branch from 56914ab to 15d0d15 Compare February 13, 2026 12:04

cyrusknopf linked an issue Feb 13, 2026 that may be closed by this pull request

Unique return item names #406

Closed

cyrusknopf force-pushed the expr/return branch from 0b906f4 to a0c927c Compare February 13, 2026 19:05

turing-db deleted a comment from github-actions bot Feb 13, 2026

cyrusknopf requested review from LucLabarriere and suhassn-turing-bio February 16, 2026 12:24

cyrusknopf commented Feb 16, 2026

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cyrusknopf force-pushed the expr/return branch 2 times, most recently from 8c55eac to 9dacd54 Compare February 17, 2026 12:42

cyrusknopf marked this pull request as ready for review February 17, 2026 12:43

cyrusknopf requested a review from rjb32 as a code owner February 17, 2026 12:43

turing-db deleted a comment from github-actions bot Feb 17, 2026

rjb32 reviewed Feb 17, 2026

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cyrusknopf commented Feb 17, 2026

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query/pipeline/processors/CountProcessor.cpp Outdated Show resolved Hide resolved

rjb32 force-pushed the expr/return branch from 9992a25 to b7413bc Compare February 18, 2026 11:28

cyrusknopf force-pushed the expr/return branch 2 times, most recently from 8d1b281 to 5ad15b6 Compare February 18, 2026 14:29

cyrusknopf commented Feb 18, 2026

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query/pipeline/processors/ExprEvalProcessor.h Outdated Show resolved Hide resolved

cyrusknopf force-pushed the expr/return branch from cb63918 to 2963ecd Compare February 20, 2026 11:40

cyrusknopf mentioned this pull request Feb 20, 2026

Correctly encode ColumnConst in JsonEncoder #445

Merged

cyrusknopf added 7 commits February 24, 2026 11:13

Add expr program in PL Gen

b7633b9

Add exception in PL gen

c05a236

Begin migration to ExprEvalProc

e5b76f9

Alloc output columns for expr proc (!return-expr)

2bcc597

Fix builder-generator interactions, queries now run (!return-expr)

2ec7573

Add processor to PL, works for block inputs (!return-expr)

cfd6faf

Remove debug (!return-expr)

243284c

cyrusknopf and others added 26 commits February 24, 2026 11:19

Add ExprEvalNode.cpp to CMake

1270d56

Action Claudebot feedback

9dbfd4e

Add unreachable paths for unary predicates

35be4ce

Docs, add unused comment for execution context parameter

321acc1

Docs, reorder includes

835c451

Add two new literal skip/limit tests

cca3b55

Use new dispatcher in CountProcessor

b8a664d

Add support for function expression function arguments

a2d9daa

Docs

177911b

Remove brace initialisation

015d081

Formatting, functor made class

1d9a98c

Add debug statements in code review script

53698e4

Space between initialiser braces

ff2ffb3

Restructure EvalExprProc::execute

1d95362

Remove brace initisialisation

be164e2

Fix formatting, pass PropertyNull by value

135b0b4

Update scripts

f6749c3

Fix brackets and concepts style

414488b

Remove unused import, add explicit on constructor

70fff09

Remove unused method

81069f3

Document CountProcessor

f2f1e36

Remove deleted import

f09acbb

Add support for PropertyNull in JSON outputs

75d7324

Fix unit tests

8644b8d

Correctly output ColumnConst in JsonEncoder

0179988

Fix rebase build issues

f538f59

cyrusknopf force-pushed the expr/return branch from 19cd1bb to f538f59 Compare February 24, 2026 10:35

cyrusknopf requested a review from rjb32 February 24, 2026 10:50

rjb32 approved these changes Feb 24, 2026

View reviewed changes

cyrusknopf merged commit d9b5e1c into main Feb 24, 2026
2 checks passed

		const ColumnTag tag = findColIt->second;

		items.push_back({tag, *name});

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github-actions bot commented Feb 18, 2026 • edited by cyrusknopf Loading Uh oh! There was an error while loading. Please reload this page.

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Claude Code Review

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cyrusknopf commented Feb 9, 2026 •

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