Mohammad Suhel Ksolves Cassandra Experties created FLINK-40201:
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Summary: [Oracle CDC] Fix compatibility with Oracle 26ai and
Debezium 3.4.2.Final
Key: FLINK-40201
URL: https://issues.apache.org/jira/browse/FLINK-40201
Project: Flink
Issue Type: Bug
Components: Flink CDC
Affects Versions: cdc-3.6.0
Reporter: Mohammad Suhel Ksolves Cassandra Experties
## Background
Flink CDC 3.6's Oracle connector vendors several Debezium internal classes
that were
written against an older Debezium API. Oracle 26ai (23.26.x) requires
features only
available in Debezium 3.4.2.Final (specifically
UnbufferedLogMinerStreamingChangeEventSource
introduced in Debezium 2.x). When Debezium 3.4.2.Final is used, the vendored
classes
produce runtime errors because they still carry old API signatures. Simply
swapping
the Debezium JAR is not sufficient — several source-level fixes are required
to align
the vendored classes with the Debezium 3.4.2 API.
## Problem
Oracle CDC connector in Flink CDC 3.6 fails with Oracle 26ai (CDB/PDB mode)
when
using Debezium 3.4.2.Final. Multiple runtime errors prevent snapshot and
streaming
CDC from working end-to-end:
1. **NoSuchMethodError on LogMinerChangeRecordEmitter**: The vendored
LogMinerChangeRecordEmitter carries a 10-arg constructor (from an older
Debezium API)
but Debezium 3.4.2's UnbufferedLogMinerStreamingChangeEventSource calls a
9-arg
constructor (rowId parameter was removed in Debezium 2.x).
2. **NullPointerException in ResumePositionProvider.close()**: The close()
method
calls sessionContext.close() without null-guarding sessionContext. If lazy
initialisation fails after connection is assigned but before
sessionContext is
assigned, close() produces a secondary NPE that hides the root cause
exception.
3. **Invalid JDBC connection string in ResumePositionProvider**: When the
connector
"database.hostname" instead of "hostname", producing a malformed JDBC URL
and
connection failure.
4. **ORA-01031 on row count query**: OracleUtils.queryApproximateRowCnt() used
ANALYZE TABLE which requires the ANALYZE ANY system privilege. Standard CDC
users do not have this privilege. Fixed by querying ALL_TABLES.NUM_ROWS
instead.
5. **ORA-00942 / schema recovery failure**: readSchemaForCapturedTables()
fails in
CDB/PDB mode because Oracle JDBC returns the PDB name as TABLE_CAT in JDBC
metadata results, but the TableId has a null catalog. Fixed by using a
catalog-agnostic filter when calling readSchema().
6. **NullPointerException on absent ROWID Connect header**: Debezium 3.4.2
removed
the getEmitConnectHeaders() override that injected a ROWID into Kafka
Connect
headers. OracleSourceFetchTaskContext.isRecordBetween() then crashes on
tables
without a primary key because headers.iterator().next() throws
NoSuchElementException when no header is present.
7. **ClassNotFoundException at runtime**: debezium-common classes (e.g.
RelationalDatabaseSchema) are referenced at runtime but were not included
in
the Maven shade assembly, causing ClassNotFoundException when the fat JAR
is used.
## Steps to Reproduce
1. Set up Oracle 26ai in CDB/PDB mode (e.g. FREE CDB + FREEPDB1)
2. Upgrade Debezium version in pom.xml to 3.4.2.Final
3. Run Oracle CDC connector with scan.startup.mode=initial
4. Observe failures listed above during snapshot and streaming phases
## Fix
- Update vendored LogMinerChangeRecordEmitter to 9-arg constructor matching
Debezium 3.4.2
- Add local ResumePositionProvider override: null-guard on sessionContext in
close() and
catch block; strip "database." prefix from JdbcConfiguration before
creating OracleConnection
- Fix OracleUtils.queryApproximateRowCnt() to use ALL_TABLES.NUM_ROWS instead
of ANALYZE TABLE
- Fix OracleSchema.getTableSchema() to use a catalog-agnostic TableFilter for
readSchema()
so it works correctly in Oracle CDB/PDB mode
- Guard isRecordBetween() against absent ROWID Connect header; fall back to
SCN-range
inclusion for tables without a primary key (multi-chunk PK-less tables
should set
scan.incremental.snapshot.chunk.key-column explicitly)
- Include debezium-common in Maven shade assembly to prevent
ClassNotFoundException at runtime
- Add EmbeddedFlinkSchemaHistory and RelationalDatabaseSchema adapters for
Debezium 3.x API
## Verification
Tested end-to-end pipeline: Oracle 26ai FREE (CDB/FREEPDB1) → Flink CDC
3.6-SNAPSHOT
→ StarRocks sink. Confirmed 3 snapshot rows and a live CDC UPDATE propagated
correctly
using Debezium 3.4.2.Final and scan.startup.mode=initial.
## Environment
- Flink CDC: 3.6-SNAPSHOT
- Debezium: 3.4.2.Final
- Oracle: 26ai (FREE edition, CDB + FREEPDB1 PDB)
- Java: 17
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