bamaer opened a new issue, #8993:
URL: https://github.com/apache/hop/issues/8993
### Apache Hop version?
2.20.0-SNAPSHOT (main, 2026-10-17)
### Java version?
21
### Operating system
macOS
### What happens
A statement with `CALL { ... } IN TRANSACTIONS` fails in the Neo4j Cypher
transform and in the Neo4j Cypher Script action. This is the batching syntax
Neo4j recommends instead of `apoc.periodic.iterate`.
```cypher
MATCH (n:Person) CALL (n) { SET n.processed = true } IN TRANSACTIONS OF 10
ROWS
```
Both fail with:
```
org.neo4j.driver.exceptions.DatabaseException: A query with 'CALL { ... } IN
TRANSACTIONS' can only be executed in an implicit transaction, but tried to
execute in an explicit transaction.
```
No nodes are updated. The same statement in `cypher-shell` (auto-commit)
updates all nodes. Tested on Neo4j 5.26.31 Community, with `hop-run`:
- Pipeline: Generate rows (1 row) → Cypher, batch size 1, not read-only, no
UNWIND.
- Workflow: Start → Neo4j Cypher Script with the statement above.
### Expected
The statement runs in an auto-commit transaction and Neo4j commits each
batch of rows.
### Cause
Neo4j only accepts `CALL { ... } IN TRANSACTIONS` in an implicit
(auto-commit) transaction. Both components run it in a managed transaction:
- Cypher transform: `runStatementsInTransaction()` and `writeUnwindList()`
use `session.executeWrite()` / `executeRead()` (`Cypher.java`). The transform
already sends some statements to `runAutoCommitStatement()` when
`IGraphDialect.isRequiringAutoCommit()` returns true. Only
`MemgraphGraphDialect` overrides that method. `Neo4jGraphDialect` keeps the
default, `false`.
- Cypher Script action: runs the whole script in one
`connection.executeWrite()` when `isSupportingSchemaChangesInTransactions()` is
true, which is the case for Neo4j (`CypherScript.java`). `executeAutoCommit()`
is only used when the dialect can't make schema changes in a transaction.
### Possible fix
- `Neo4jGraphDialect.isRequiringAutoCommit()` returns true for statements
with `CALL ... { ... } IN TRANSACTIONS`, for both the `CALL {` and `CALL (vars)
{` forms. The Cypher transform then uses the existing auto-commit path.
- The Cypher Script action runs statements that need auto-commit on their
own, and the rest in a transaction, as the Cypher transform does.
- Integration test in `integration-tests/neo4j` for both components.
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