Implement predicate functions: all(), any(), none(), single() by gregfelice · Pull Request #2359 · apache/age

gregfelice · 2026-03-25T02:47:11Z

Summary

Implements the four openCypher predicate functions (issues #552, #553, #555, #556):

all(x IN list WHERE predicate) — true if all elements match
any(x IN list WHERE predicate) — true if at least one matches
none(x IN list WHERE predicate) — true if no elements match
single(x IN list WHERE predicate) — true if exactly one matches

These are among the most requested Cypher features for AGE and are critical for users migrating from Neo4j and Kuzu (recently archived).

Implementation

Approach: Builds on the existing list comprehension infrastructure (unnest-based subqueries with child parsestates for variable scoping).

SQL transformation strategy:

all() → NOT EXISTS (SELECT 1 FROM unnest(list) AS x WHERE NOT predicate)
any() → EXISTS (SELECT 1 FROM unnest(list) AS x WHERE predicate)
none() → NOT EXISTS (SELECT 1 FROM unnest(list) AS x WHERE predicate)
single() → (SELECT count(*) FROM unnest(list) AS x WHERE predicate) = 1

EXISTS/NOT EXISTS short-circuits on first match for optimal performance.

Files changed (12):

File	Change
`cypher_nodes.h`	New `cypher_predicate_function` node type with `CPFK_ALL/ANY/NONE/SINGLE` enum
`ag_nodes.h` / `ag_nodes.c`	Node registration
`cypher_outfuncs.h` / `cypher_outfuncs.c`	Serialization
`cypher_kwlist.h`	Three new keywords: `ANY_P`, `NONE`, `SINGLE`
`cypher_gram.y`	Grammar rules in `expr_func_subexpr`, `build_predicate_function_node()` helper, `extract_iter_variable_name()` shared helper, keywords added to `safe_keywords`
`cypher_clause.c`	`transform_cypher_predicate_function()` — builds query tree from predicate node
`cypher_analyze.c`	Expression walker for new node type
`Makefile`	Register new regression test
`regress/sql/predicate_functions.sql`	New test file
`regress/expected/predicate_functions.out`	Expected output

Backward compatibility:

ANY_P, NONE, SINGLE added to safe_keywords so they work as property keys and label names (e.g., {any: 1, none: 2, single: 3})
ALL was already a reserved keyword with safe_keywords entry
No grammar conflicts (verified: zero new shift/reduce or reduce/reduce warnings)

Regression Tests

28 test queries covering:

Basic true/false for each function
Empty list edge cases (vacuous truth for all()/none(), false for any()/single())
Graph data integration (MATCH (u) WHERE all(x IN u.vals WHERE ...))
Boolean combinations (any(...) AND all(...))
Nested predicates (any(x IN ... WHERE all(y IN ... WHERE ...)))
Keyword backward compatibility ({any: 1, none: 2, single: 3})
Deterministic ordering (all graph queries use ORDER BY)

All 32 regression tests pass (31 existing + 1 new).

Implement the four openCypher predicate functions (issues apache#552, apache#553, apache#555, apache#556) that test list elements against a predicate: all(x IN list WHERE predicate) -- true if all elements match any(x IN list WHERE predicate) -- true if at least one matches none(x IN list WHERE predicate) -- true if no elements match single(x IN list WHERE predicate) -- true if exactly one matches Implementation approach: - Add cypher_predicate_function node type with CPFK_ALL/ANY/NONE/SINGLE kind enum, reusing the list comprehension's unnest-based transformation - Grammar rules in expr_func_subexpr (alongside EXISTS, COALESCE, COUNT) - Transform to efficient SQL sublinks: all() -> NOT EXISTS (SELECT 1 FROM unnest WHERE NOT pred) any() -> EXISTS (SELECT 1 FROM unnest WHERE pred) none() -> NOT EXISTS (SELECT 1 FROM unnest WHERE pred) single() -> (SELECT count(*) FROM unnest WHERE pred) = 1 - Three new keywords (ANY_P, NONE, SINGLE) added to safe_keywords for backward compatibility as property keys and label names - Shared extract_iter_variable_name() helper for variable validation All 32 regression tests pass. New predicate_functions test covers basic semantics, empty lists, graph data integration, boolean combinations, nested predicates, and keyword backward compatibility. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Adds support for the openCypher predicate functions all(), any(), none(), and single() by introducing a new AST node and transforming it into unnest(...)-based SQL subqueries during parsing/analyzing, with a new regression test suite.

Changes:

Add new cypher_predicate_function AST node (+ enum kind) and register/serialize it as an ExtensibleNode.
Extend the Cypher grammar with all/any/none/single(variable IN list WHERE predicate) and add keywords to the lexer + safe_keywords.
Implement query-tree transformation for predicate functions and add regression tests (predicate_functions).

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/include/parser/cypher_kwlist.h	Adds `any/none/single` as Cypher keywords.
src/backend/parser/cypher_gram.y	Adds grammar rules + helper to build predicate-function nodes and wraps them in SubLinks.
src/include/nodes/cypher_nodes.h	Introduces `cypher_predicate_function` node + kind enum.
src/include/nodes/ag_nodes.h	Registers new node tag for predicate functions.
src/backend/nodes/ag_nodes.c	Adds node name and ExtensibleNode methods entry for predicate-function node.
src/include/nodes/cypher_outfuncs.h	Declares serialization function for the new node.
src/backend/nodes/cypher_outfuncs.c	Implements serialization for `cypher_predicate_function`.
src/backend/parser/cypher_clause.c	Transforms predicate-function node into `unnest`-based subqueries (EXISTS / count).
src/backend/parser/cypher_analyze.c	Adds expression walker support for the new node type.
Makefile	Registers the new `predicate_functions` regression test.
regress/sql/predicate_functions.sql	Adds regression SQL coverage for predicate functions.
regress/expected/predicate_functions.out	Adds expected output for the new regression test.

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src/backend/parser/cypher_clause.c

src/backend/parser/cypher_gram.y

regress/sql/predicate_functions.sql

src/backend/parser/cypher_clause.c

jrgemignani · 2026-03-25T20:56:03Z

@gregfelice Please see the above comments by Copilot

… perf, tests - Rewrite predicate functions from EXISTS_SUBLINK to EXPR_SUBLINK with aggregate-based CASE expressions (bool_or + IS TRUE/FALSE/NULL) to preserve three-valued Cypher NULL semantics - Add list_length check in extract_iter_variable_name() to reject qualified names like x.y as iterator variables - Add copy/read support for cypher_predicate_function ExtensibleNode to prevent query rewriter crashes - Use IS TRUE filtering in single() count (LIMIT 2 optimization breaks correlated variable refs in graph contexts -- documented) - Add 13 NULL regression tests: null list input, null elements, null predicates for all four functions Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gregfelice · 2026-03-25T21:20:52Z

Addressed all 4 Copilot suggestions:

NULL semantics — Rewrote from EXISTS_SUBLINK to EXPR_SUBLINK with aggregate-based CASE expressions (bool_or(pred IS TRUE/FALSE) + bool_or(pred IS NULL)) to preserve three-valued Cypher NULL semantics. any(x IN [NULL] WHERE x > 0) now correctly returns NULL instead of false.
Unqualified iterator check — Added list_length(cref->fields) != 1 validation in extract_iter_variable_name(). Qualified names like x.y now error with "qualified name not allowed as iterator variable".
NULL regression tests — Added 13 new test cases covering: NULL list input for all four functions, null elements in lists, literal null predicates, and mixed null/non-null elements.
single() performance — Applied IS TRUE filtering so NULL predicates aren't counted. The LIMIT 2 optimization breaks correlated variable references in graph property contexts (e.g., MATCH (u) WHERE single(x IN u.vals WHERE ...)), documented with TODO for future optimization pass.

Bonus: Added copy/read support for cypher_predicate_function ExtensibleNode to prevent "unexpected copyObject()" crashes when PostgreSQL's query rewriter copies expression trees.

All 32 regression tests pass (predicate_functions: ok).

jrgemignani · 2026-03-25T23:47:44Z

@gregfelice We'll see what Copilot thinks ;) Btw, in the future, can you put your comments in the reply to Copilot, please.

Copilot

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

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src/backend/parser/cypher_gram.y

src/backend/parser/cypher_clause.c

…ate.h 1. Add NULL-list guard for all predicate functions (all/any/none/single). Wraps the result with CASE WHEN list IS NULL THEN NULL ELSE <result> END in the grammar layer. This fixes single(x IN null WHERE ...) returning false instead of NULL. The expr pointer is safely shared between the NullTest and the predicate function node because AGE's expression transformer creates new nodes without modifying the parse tree in-place. 2. Fix single() block comment in transform_cypher_predicate_function: described LIMIT 2 optimization but implementation uses plain count(*). Updated comment to match actual implementation. 3. Keep #include "catalog/pg_aggregate.h" -- Copilot suggested removal but AGGKIND_NORMAL macro requires it (build fails without it). Regression test: predicate_functions OK. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 2 comments.

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Copilot · 2026-03-26T18:43:24Z

src/backend/parser/cypher_clause.c

+ * Transform a cypher_predicate_function node into a query tree.
+ *
+ * Generates aggregate-based queries that preserve Cypher's three-valued
+ * NULL semantics.  The grammar layer wraps the SubLink with a
+ * CASE WHEN list IS NULL THEN NULL ELSE (subquery) END guard so all
+ * four functions return NULL when the input list is NULL.
+ *
+ * For all()/any()/none():
+ *   SELECT CASE WHEN bool_or(pred IS TRUE/FALSE) THEN ...
+ *               WHEN bool_or(pred IS NULL)       THEN NULL
+ *               ELSE ... END
+ *   FROM unnest(list) AS x
+ *


The PR description says all/any/none are transformed to EXISTS/NOT EXISTS and that these forms short-circuit, but the implemented transform uses bool_or() aggregates + CASE (which will evaluate all rows). Please update the PR description to match the actual aggregate-based approach (or implement the EXISTS/NOT EXISTS strategy if short-circuiting is a requirement).

Copilot · 2026-03-26T18:43:24Z

src/backend/parser/cypher_gram.y

 /* helper function to build a list_comprehension grammar node */
 static Node *build_list_comprehension_node(Node *var, Node *expr,
                                           Node *where, Node *mapping_expr,


Now that extract_iter_variable_name() was introduced to validate iterator variables (including rejecting qualified ColumnRefs), build_list_comprehension_node() should ideally reuse it so var IN list validation is consistent between list comprehensions and all/any/none/single. Otherwise list comprehensions can still accept qualified iterator names and silently use only the first field, which can lead to confusing behavior/errors.

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Implement predicate functions: all(), any(), none(), single()#2359

Implement predicate functions: all(), any(), none(), single()#2359
gregfelice wants to merge 3 commits intoapache:masterfrom
gregfelice:feature_predicate_functions

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gregfelice commented Mar 25, 2026

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