Debezium Connector for Oracle

Overview

Debezium ingests change events from Oracle using the XStream API or directly by LogMiner. In order to use the XStream API, you need to have a license for the GoldenGate product (though it is not required that GoldenGate itself is installed).

How the Oracle Connector Works

To optimally configure and run a Debezium Oracle connector, it is helpful to understand how the connector performs snapshots, streams change events, determines Kafka topic names, and uses metadata.

Snapshots

Most Oracle servers are configured to not retain the complete history of the database in the redo logs, so the Debezium Oracle connector would be unable to see the entire history of the database by simply reading the logs. Consequently, the first time the connector starts, it performs an initial consistent snapshot of the database. the default behavior for perofmring a snapshot consists of the following steps. you can change this behavior by setting the snapshot.mode connector configuration property to a value other than initial.

1. Determine the tables to be captured

2. Obtain an IN EXCLUSIVE MODE lock on each of the monitored tables to ensure that no structural changes can occur to any of the tables.

3. Read the current SCN (“system change number”) position in the server’s redo log.

4. Capture the structure of all relevant tables.

5. Release the locks obtained in step 2, i.e. the locks are held only for a short period of time.

6. Scan all of the relevant database tables and schemas as valid at the SCN position read in step 3 (SELECT * FROM …​ AS OF SCN 123), and generate a READ event for each row and write that event to the appropriate table-specific Kafka topic.

7. Record the successful completion of the snapshot in the connector offsets.

If the connector fails, is rebalanced, or stops after step 1 begins but before step 7 completes, upon restart the connector will begin a new snapshot. After the connector completes its initial snapshot, the Debezium connector continues streaming from the position that it read in step 3. This ensures that the connector does not miss any updates. If the connector stops again for any reason, upon restart, the connector continues streaming changes from where it previously left off.

Topics Names

Schema Change Topic

The Debezium Oracle connector stores the history of schema changes in a database history topic. This topic reflects an internal connector state and you should not use it directly. Applications that require notifications about schema changes should obtain the information from the public schema change topic. the connector writes all of these events to a Kafka topic named <serverName>, where serverName is the name of the connector that is specified in the database.server.name configuration property.

Debezium emits a new message to this topic whenever a new table is streamed from or when the structure of the table is altered (schema evolution procedure must be followed). The message contains a logical representation of the table schema.

The example of the message is:

{
  "schema": {
  ...
  },
  "payload": {
    "source": {
      "version": "1.4.2.Final",
      "connector": "oracle",
      "name": "server1",
      "ts_ms": 1588252618953,
      "snapshot": "true",
      "db": "ORCLPDB1",
      "schema": "DEBEZIUM",
      "table": "CUSTOMERS",
      "txId" : null,
      "scn" : "1513734",
      "commit_scn": "1513734",
      "lcr_position" : null
    },
    "databaseName": "ORCLPDB1", (1)
    "schemaName": "DEBEZIUM", (1)
    "ddl": "CREATE TABLE \"DEBEZIUM\".\"CUSTOMERS\" \n   (    \"ID\" NUMBER(9,0) NOT NULL ENABLE, \n    \"FIRST_NAME\" VARCHAR2(255), \n    \"LAST_NAME" VARCHAR2(255), \n    \"EMAIL\" VARCHAR2(255), \n     PRIMARY KEY (\"ID\") ENABLE, \n     SUPPLEMENTAL LOG DATA (ALL) COLUMNS\n   ) SEGMENT CREATION IMMEDIATE \n  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 \n NOCOMPRESS LOGGING\n  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645\n  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1\n  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)\n  TABLESPACE \"USERS\" ", (2)
    "tableChanges": [ (3)
      {
        "type": "CREATE", (4)
        "id": "\"ORCLPDB1\".\"DEBEZIUM\".\"CUSTOMERS\"", (5)
        "table": { (6)
          "defaultCharsetName": null,
          "primaryKeyColumnNames": [ (7)
            "ID"
          ],
          "columns": [ (8)
            {
              "name": "ID",
              "jdbcType": 2,
              "nativeType": null,
              "typeName": "NUMBER",
              "typeExpression": "NUMBER",
              "charsetName": null,
              "length": 9,
              "scale": 0,
              "position": 1,
              "optional": false,
              "autoIncremented": false,
              "generated": false
            },
            {
              "name": "FIRST_NAME",
              "jdbcType": 12,
              "nativeType": null,
              "typeName": "VARCHAR2",
              "typeExpression": "VARCHAR2",
              "charsetName": null,
              "length": 255,
              "scale": null,
              "position": 2,
              "optional": false,
              "autoIncremented": false,
              "generated": false
            },
            {
              "name": "LAST_NAME",
              "jdbcType": 12,
              "nativeType": null,
              "typeName": "VARCHAR2",
              "typeExpression": "VARCHAR2",
              "charsetName": null,
              "length": 255,
              "scale": null,
              "position": 3,
              "optional": false,
              "autoIncremented": false,
              "generated": false
            },
            {
              "name": "EMAIL",
              "jdbcType": 12,
              "nativeType": null,
              "typeName": "VARCHAR2",
              "typeExpression": "VARCHAR2",
              "charsetName": null,
              "length": 255,
              "scale": null,
              "position": 4,
              "optional": false,
              "autoIncremented": false,
              "generated": false
            }
          ]
        }
      }
    ]
  }
}

In messages that the connector sends to the schema change topic, the key is the name of the database that contains the schema change. In the following example, the payload field contains the key:

{
  "schema": {
    "type": "struct",
    "fields": [
      {
        "type": "string",
        "optional": false,
        "field": "databaseName"
      }
    ],
    "optional": false,
    "name": "io.debezium.connector.oracle.SchemaChangeKey"
  },
  "payload": {
    "databaseName": "ORCLPDB1"
  }
}

Transaction Metadata

Debezium can generate events that represents tranaction metadata boundaries and enrich data messages.

Transaction boundaries

Debezium generates events for every transaction BEGIN and END. Every event contains

• status - BEGIN or END

• id - string representation of unique transaction identifier

• event_count (for END events) - total number of events emmitted by the transaction

• data_collections (for END events) - an array of pairs of data_collection and event_count that provides number of events emitted by changes originating from given data collection

Following is an example of what a message looks like:

{
  "status": "BEGIN",
  "id": "5.6.641",
  "event_count": null,
  "data_collections": null
}
{
  "status": "END",
  "id": "5.6.641",
  "event_count": 2,
  "data_collections": [
    {
      "data_collection": "ORCLPDB1.DEBEZIUM.CUSTOMER",
      "event_count": 1
    },
    {
      "data_collection": "ORCLPDB1.DEBEZIUM.ORDER",
      "event_count": 1
    }
  ]
}

The transaction events are written to the topic named <database.server.name>.transaction.

Data events enrichment

When transaction metadata is enabled the data message Envelope is enriched with a new transaction field. This field provides information about every event in the form of a composite of fields:

• id - string representation of unique transaction identifier

• total_order - the absolute position of the event among all events generated by the transaction

• data_collection_order - the per-data collection position of the event among all events that were emitted by the transaction

Following is an example of what a message looks like:

{
  "before": null,
  "after": {
    "pk": "2",
    "aa": "1"
  },
  "source": {
...
  },
  "op": "c",
  "ts_ms": "1580390884335",
  "transaction": {
    "id": "5.6.641",
    "total_order": "1",
    "data_collection_order": "1"
  }
}

Data change events

All data change events produced by the Oracle connector have a key and a value, although the structure of the key and value depend on the table from which the change events originated (see Topic names).

Debezium and Kafka Connect are designed around continuous streams of event messages, and the structure of these events may change over time. This could be difficult for consumers to deal with, so to make it easy Kafka Connect makes each event self-contained. Every message key and value has two parts: a schema and payload. The schema describes the structure of the payload, while the payload contains the actual data.

Change event keys

For a given table, the change event’s key will have a structure that contains a field for each column in the primary key (or unique key constraint) of the table at the time the event was created.

Consider a customers table defined in the inventory database schema:

CREATE TABLE customers (
  id NUMBER(9) GENERATED BY DEFAULT ON NULL AS IDENTITY (START WITH 1001) NOT NULL PRIMARY KEY,
  first_name VARCHAR2(255) NOT NULL,
  last_name VARCHAR2(255) NOT NULL,
  email VARCHAR2(255) NOT NULL UNIQUE
);

If the database.server.name configuration property has the value server1, every change event for the customers table while it has this definition will feature the same key structure, which in JSON looks like this:

{
    "schema": {
        "type": "struct",
        "fields": [
            {
                "type": "int32",
                "optional": false,
                "field": "ID"
            }
        ],
        "optional": false,
        "name": "server1.INVENTORY.CUSTOMERS.Key"
    },
    "payload": {
        "ID": 1004
    }
}

The schema portion of the key contains a Kafka Connect schema describing what is in the key portion, and in our case that means that the payload value is not optional, is a structure defined by a schema named server1.DEBEZIUM.CUSTOMERS.Key, and has one required field named id of type int32. If you look at the value of the key’s payload field, you can see that it is indeed a structure (which in JSON is just an object) with a single id field, whose value is 1004.

Therefore, you can interpret this key as describing the row in the inventory.customers table (output from the connector named server1) whose id primary key column had a value of 1004.

Change event values

Like the message key, the value of a change event message has a schema section and payload section. The payload section of every change event value produced by the Oracle connector has an envelope structure with the following fields:

• op is a mandatory field that contains a string value describing the type of operation. Values for the Oracle connector are c for create (or insert), u for update, d for delete, and r for read (in the case of a snapshot).

• before is an optional field that if present contains the state of the row before the event occurred. The structure will be described by the server1.INVENTORY.CUSTOMERS.Value Kafka Connect schema, which the server1 connector uses for all rows in the inventory.customers table.

• after is an optional field that if present contains the state of the row after the event occurred. The structure is described by the same server1.INVENTORY.CUSTOMERS.Value Kafka Connect schema used in before.

• source is a mandatory field that contains a structure describing the source metadata for the event, which in the case of Oracle contains these fields: the Debezium version, the connector name, whether the event is part of an ongoing snapshot or not, the transaction id (not while snapshotting), the SCN of the change, and a timestamp representing the point in time when the record was changed in the source database (during snapshotting, this is the point in time of snapshotting).

• ts_ms is optional and if present contains the time (using the system clock in the JVM running the Kafka Connect task) at which the connector processed the event.

And of course, the schema portion of the event message’s value contains a schema that describes this envelope structure and the nested fields within it.

Create events

Let’s look at what a create event value might look like for our customers table:

{
    "schema": {
        "type": "struct",
        "fields": [
            {
                "type": "struct",
                "fields": [
                    {
                        "type": "int32",
                        "optional": false,
                        "field": "ID"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "FIRST_NAME"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "LAST_NAME"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "EMAIL"
                    }
                ],
                "optional": true,
                "name": "server1.DEBEZIUM.CUSTOMERS.Value",
                "field": "before"
            },
            {
                "type": "struct",
                "fields": [
                    {
                        "type": "int32",
                        "optional": false,
                        "field": "ID"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "FIRST_NAME"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "LAST_NAME"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "EMAIL"
                    }
                ],
                "optional": true,
                "name": "server1.DEBEZIUM.CUSTOMERS.Value",
                "field": "after"
            },
            {
                "type": "struct",
                "fields": [
                    {
                        "type": "string",
                        "optional": true,
                        "field": "version"
                    },
                    {
                        "type": "string",
                        "optional": false,
                        "field": "name"
                    },
                    {
                        "type": "int64",
                        "optional": true,
                        "field": "ts_ms"
                    },
                    {
                        "type": "string",
                        "optional": true,
                        "field": "txId"
                    },
                    {
                        "type": "int64",
                        "optional": true,
                        "field": "scn"
                    },
                    {
                        "type": "int64",
                        "optional": true,
                        "field": "commit_scn"
                    },
                    {
                        "type": "boolean",
                        "optional": true,
                        "field": "snapshot"
                    }
                ],
                "optional": false,
                "name": "io.debezium.connector.oracle.Source",
                "field": "source"
            },
            {
                "type": "string",
                "optional": false,
                "field": "op"
            },
            {
                "type": "int64",
                "optional": true,
                "field": "ts_ms"
            }
        ],
        "optional": false,
        "name": "server1.DEBEZIUM.CUSTOMERS.Envelope"
    },
    "payload": {
        "before": null,
        "after": {
            "ID": 1004,
            "FIRST_NAME": "Anne",
            "LAST_NAME": "Kretchmar",
            "EMAIL": "annek@noanswer.org"
        },
        "source": {
            "version": "0.9.0.Alpha1",
            "name": "server1",
            "ts_ms": 1520085154000,
            "txId": "6.28.807",
            "scn": 2122185,
            "commit_scn": 2122185,
            "snapshot": false
        },
        "op": "c",
        "ts_ms": 1532592105975
    }
}

If we look at the schema portion of this event’s value, we can see the schema for the envelope, the schema for the source structure (which is specific to the Oracle connector and reused across all events), and the table-specific schemas for the before and after fields.

If we look at the payload portion of this event’s value, we can see the information in the event, namely that it is describing that the row was created (since op=c), and that the after field value contains the values of the new inserted row’s’ ID, FIRST_NAME, LAST_NAME, and EMAIL columns.

Update events

The value of an update change event on this table will actually have the exact same schema, and its payload will be structured the same but will hold different values. Here’s an example:

{
    "schema": { ... },
    "payload": {
        "before": {
            "ID": 1004,
            "FIRST_NAME": "Anne",
            "LAST_NAME": "Kretchmar",
            "EMAIL": "annek@noanswer.org"
        },
        "after": {
            "ID": 1004,
            "FIRST_NAME": "Anne",
            "LAST_NAME": "Kretchmar",
            "EMAIL": "anne@example.com"
        },
        "source": {
            "version": "0.9.0.Alpha1",
            "name": "server1",
            "ts_ms": 1520085811000,
            "txId": "6.9.809",
            "scn": 2125544,
            "commit_scn": 2125544,
            "snapshot": false
        },
        "op": "u",
        "ts_ms": 1532592713485
    }
}

When we compare this to the value in the insert event, we see a couple of differences in the payload section:

• The op field value is now u, signifying that this row changed because of an update

• The before field now has the state of the row with the values before the database commit

• The after field now has the updated state of the row, and here was can see that the EMAIL value is now anne@example.com.

• The source field structure has the same fields as before, but the values are different since this event is from a different position in the redo log.

• The ts_ms shows the timestamp that Debezium processed this event.

There are several things we can learn by just looking at this payload section. We can compare the before and after structures to determine what actually changed in this row because of the commit. The source structure tells us information about Oracle’s record of this change (providing traceability), but more importantly this has information we can compare to other events in this and other topics to know whether this event occurred before, after, or as part of the same Oracle commit as other events.

Delete events

So far we’ve seen samples of create and update events. Now, let’s look at the value of a delete event for the same table. Once again, the schema portion of the value will be exactly the same as with the create and update events:

{
    "schema": { ... },
    "payload": {
        "before": {
            "ID": 1004,
            "FIRST_NAME": "Anne",
            "LAST_NAME": "Kretchmar",
            "EMAIL": "anne@example.com"
        },
        "after": null,
        "source": {
            "version": "0.9.0.Alpha1",
            "name": "server1",
            "ts_ms": 1520085153000,
            "txId": "6.28.807",
            "scn": 2122184,
            "commit_scn": 2122184,
            "snapshot": false
        },
        "op": "d",
        "ts_ms": 1532592105960
    }
}

If we look at the payload portion, we see a number of differences compared with the create or update event payloads:

• The op field value is now d, signifying that this row was deleted

• The before field now has the state of the row that was deleted with the database commit.

• The after field is null, signifying that the row no longer exists

• The source field structure has many of the same values as before, except the ts_ms, scn and txId fields have changed

• The ts_ms shows the timestamp that Debezium processed this event.

This event gives a consumer all kinds of information that it can use to process the removal of this row.

The Oracle connector’s events are designed to work with Kafka log compaction, which allows for the removal of some older messages as long as at least the most recent message for every key is kept. This allows Kafka to reclaim storage space while ensuring the topic contains a complete dataset and can be used for reloading key-based state.

When a row is deleted, the delete event value listed above still works with log compaction, since Kafka can still remove all earlier messages with that same key. But only if the message value is null will Kafka know that it can remove all messages with that same key. To make this possible, Debezium’s Oracle connector always follows the delete event with a special tombstone event that has the same key but null value.

Data Type mappings

The Oracle conenctor represents changes to rows with events that are structured like the table in which the rows exists. The event contains a field for each column value. How that value is represented in the event depends on the Oracle data type of the column. The following sections describe how the connector maps oracle data types to a litearl type and a semantic type in event fields.

• litearl type describes how the value is literally represented using Kafka Connect schema types: INT8, INT16, INT32, INT64, FLOAT32, FLOAT64, BOOLEAN, STRING, BYTES, ARRAY, MAP, and STRUCT.

• semantic type describes how the Kafka Connect schema captures the meaning of the field using the name of the Kafka Connect schema for the field.

Support for further data types will be added in subsequent releases. Please file a JIRA issue for any specific types that may be missing.

Character types

The following table describes how the connector maps character types.

Numeric types

The following table describes how the connector maps numeric types.

Decimal types

The setting of the Oracle connector configuration property, decimal.handling.mode determines how the connector maps decimal types.

When the decimal.handling.mode property is set to precise, the connector uses Kafka Connect org.apache.kafka.connect.data.Decimal logical type for all DECIMAL and NUMERIC columns. This is the default mode.

However, when the decimal.handling.mode property is set to double, the connector will represent the values as Java double values with schema type FLOAT64.

The last possible setting for the decimal.handling.mode configuration property is string. In this case, the connector reprsents DECIMAL and NUMERIC values as their formatted string representation with schema type STRING.

Temporal types

The following table describes how the connector maps temporal types.

Setting up Oracle

The following database set up steps are necessary to use the Debezium Oracle connector. These steps assume the use of the multitenancy configuration with a container database and at least one pluggable database. If you intend to use a non-multitenancy configuration, the following steps may require adjustment.

You can find a template for setting up Oracle in a virtual machine (via Vagrant) in the oracle-vagrant-box/ repository.

Preparing the Database

Configuration needed for Oracle XStream

ORACLE_SID=ORCLCDB dbz_oracle sqlplus /nolog
CONNECT sys/top_secret AS SYSDBA
alter system set db_recovery_file_dest_size = 5G;
alter system set db_recovery_file_dest = '/opt/oracle/oradata/recovery_area' scope=spfile;
alter system set enable_goldengate_replication=true;
shutdown immediate
startup mount
alter database archivelog;
alter database open;
-- Should show "Database log mode: Archive Mode"
archive log list
exit;

Configuration needed for Oracle LogMiner

ORACLE_SID=ORACLCDB dbz_oracle sqlplus /nolog
CONNECT sys/top_secret AS SYSDBA
alter system set db_recovery_file_dest_size = 10G;
alter system set db_recovery_file_dest = '/opt/oracle/oradta/recovery_area' scope=spfile;
shutdown immediate
startup mount
alter database archivelog;
alter database open;
-- Should now "Database log mode: Archive Mode"
archive log list
exit;

In addition, supplemental logging must be enabled for captured tables or the database in order for data changes to capture the before state of changed database rows. The following illustrates how to configure this on a specific table, which is the ideal choice to minimize the amount of information captured in the Oracle redo logs.

ALTER TABLE inventory.customers ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;

Creating Users for the connector

The Debezium Oracle connector requires that users accounts be set up with specific permissions so that the connector can capture change events. The following briefly describes these user configurations using a multi-tenant database model.

• Creating users for Oracle XStream

• Creating users for Oracle LogMiner

Creating an XStream Administrator user

sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE TABLESPACE xstream_adm_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/xstream_adm_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLPDB1 as sysdba
  CREATE TABLESPACE xstream_adm_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/xstream_adm_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE USER c##xstrmadmin IDENTIFIED BY xsa
    DEFAULT TABLESPACE xstream_adm_tbs
    QUOTA UNLIMITED ON xstream_adm_tbs
    CONTAINER=ALL;
  GRANT CREATE SESSION, SET CONTAINER TO c##xstrmadmin CONTAINER=ALL;
  BEGIN
     DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
        grantee                 => 'c##xstrmadmin',
        privilege_type          => 'CAPTURE',
        grant_select_privileges => TRUE,
        container               => 'ALL'
     );
  END;
  /
  exit;

Creating the connector’s XStream user

sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE TABLESPACE xstream_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/xstream_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLPDB1 as sysdba
  CREATE TABLESPACE xstream_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/xstream_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE USER c##xstrm IDENTIFIED BY xs
    DEFAULT TABLESPACE xstream_tbs
    QUOTA UNLIMITED ON xstream_tbs
    CONTAINER=ALL;
  GRANT CREATE SESSION TO c##xstrm CONTAINER=ALL;
  GRANT SET CONTAINER TO c##xstrm CONTAINER=ALL;
  GRANT SELECT ON V_$DATABASE to c##xstrm CONTAINER=ALL;
  GRANT FLASHBACK ANY TABLE TO c##xstrm CONTAINER=ALL;
  GRANT SELECT_CATALOG_ROLE TO c##xstrm CONTAINER=ALL;
  GRANT EXECUTE_CATALOG_ROLE TO c##xstrm CONTAINER=ALL;
  exit;

Creating the connector’s LogMiner user

sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE TABLESPACE logminer_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/logminer_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLPDB1 as sysdba
  CREATE TABLESPACE logminer_tbs DATAFILE '/opt/oracle/oradata/ORCLCDB/ORCLPDB1/logminer_tbs.dbf'
    SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
  exit;
sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
  CREATE USER c##logminer IDENTIFIED BY lm
    DEFAULT TABLESPACE logminer_tbs
    QUOTA UNLIMITED ON logminer_tbs
    CONTAINER=ALL;
  GRANT CREATE SESSION TO c##logminer CONTAINER=ALL;
  GRANT SET CONTAINER TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$DATABASE to c##logminer CONTAINER=ALL;
  GRANT FLASHBACK ANY TABLE TO c##logminer CONTAINER=ALL;
  GRANT SELECT ANY TABLE TO c##logminer CONTAINER=ALL;
  GRANT SELECT_CATALOG_ROLE TO c##logminer CONTAINER=ALL;
  GRANT EXECUTE_CATALOG_ROLE TO c##logminer CONTAINER=ALL;
  GRANT SELECT ANY TRANSACTION TO c##logminer CONTAINER=ALL;
  GRANT LOGMINING TO c##logminer CONTAINER=ALL;
  GRANT CREATE TABLE TO c##logminer CONTAINER=ALL;
  GRANT LOCK ANY TABLE TO c##logminer CONTAINER=ALL;
  GRANT ALTER ANY TABLE TO c##logminer CONTAINER=ALL;
  GRANT CREATE SEQUENCE TO c##logminer CONTAINER=ALL;
  GRANT EXECUTE ON DBMS_LOGMNR TO c##logminer CONTAINER=ALL;
  GRANT EXECUTE ON DBMS_LOGMNR_D TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOG TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOG_HISTORY TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOGMNR_LOGS TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOGMNR_CONTENTS TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOGMNR_PARAMETERS TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$LOGFILE TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$ARCHIVED_LOG TO c##logminer CONTAINER=ALL;
  GRANT SELECT ON V_$ARCHIVE_DEST_STATUS TO c##logminer CONTAINER=ALL;
  exit;

Create an XStream Outbound Server

Create an XStream Outbound server (given the right privileges, this may be done automatically by the connector going forward, see DBZ-721):

Create an XStream Outbound Server

sqlplus c##xstrmadmin/xsa@//localhost:1521/ORCLCDB
DECLARE
  tables  DBMS_UTILITY.UNCL_ARRAY;
  schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
    tables(1)  := NULL;
    schemas(1) := 'debezium';
  DBMS_XSTREAM_ADM.CREATE_OUTBOUND(
    server_name     =>  'dbzxout',
    table_names     =>  tables,
    schema_names    =>  schemas);
END;
/
exit;

Configure the XStream user account to connect to the XStream Outbound Server

sqlplus sys/top_secret@//localhost:1521/ORCLCDB as sysdba
BEGIN
  DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
    server_name  => 'dbzxout',
    connect_user => 'c##xstrm');
END;
/
exit;

Deploying a Connector

Due to licensing requirements, the Debezium Oracle Connector does not ship with the Oracle JDBC driver and the XStream API JAR. You can obtain them for free by downloading the Oracle Instant Client.

Extract the archive and navigate to the Instant Client directory. Copy ojdbc<version>.jar and xstreams.jar into Kafka’s libs directory. Lastly, create an environment variable, LD_LIBRARY_PATH, that points to the instant client directory, as shown below:

LD_LIBRARY_PATH=/path/to/instant_client/

Example Configuration

The following shows an example JSON request for registering an instance of the Debezium Oracle connector:

{
    "name": "inventory-connector",
    "config": {
        "connector.class" : "io.debezium.connector.oracle.OracleConnector",
        "tasks.max" : "1",
        "database.server.name" : "server1",
        "database.hostname" : "<oracle ip>",
        "database.port" : "1521",
        "database.user" : "c##xstrm",
        "database.password" : "xs",
        "database.dbname" : "ORCLCDB",
        "database.pdb.name" : "ORCLPDB1",
        "database.out.server.name" : "dbzxout",
        "database.history.kafka.bootstrap.servers" : "kafka:9092",
        "database.history.kafka.topic": "schema-changes.inventory"
    }
}

When using a more complex Oracle deployment or needing to use TNS names, then a raw JDBC url can be provided instead of a single hostname-port pair. Here is a similar example but that just passes the raw jdbc url:

{
    "name": "inventory-connector",
    "config": {
        "connector.class" : "io.debezium.connector.oracle.OracleConnector",
        "tasks.max" : "1",
        "database.server.name" : "server1",
        "database.user" : "c##xstrm",
        "database.password" : "xs",
        "database.url": "jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(LOAD_BALANCE=OFF)(FAILOVER=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=<oracle ip 1>)(PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=<oracle ip 2>)(PORT=1521)))(CONNECT_DATA=SERVICE_NAME=)(SERVER=DEDICATED)))",
        "database.dbname" : "ORCLCDB",
        "database.pdb.name" : "ORCLPDB1",
        "database.out.server.name" : "dbzxout",
        "database.history.kafka.bootstrap.servers" : "kafka:9092",
        "database.history.kafka.topic": "schema-changes.inventory"
    }
}

Pluggable vs Non-Plugable databases

The Debezium Oracle connector supports both deployment practices of pluggable databases (CDB mode) as well as non-pluggable databases (non-CDB mode).

Example configuration using non-CDB (Non Pluggable Database) installations

{
  "config": {
    "connector.class" : "io.debezium.connector.oracle.OracleConnector",
    "tasks.max" : "1",
    "database.server.name" : "server1",
    "database.hostname" : "<oracle ip>",
    "database.port" : "1521",
    "database.user" : "c##xstrm",
    "database.password" : "xs",
    "database.dbname" : "ORCLCDB",
    "database.out.server.name" : "dbzxout",
    "database.history.kafka.bootstrap.servers" : "kafka:9092",
    "database.history.kafka.topic": "schema-changes.inventory"
  }
}

Example configuration using CDB (Pluggable Database) installations

{
  "config": {
    "connector.class" : "io.debezium.connector.oracle.OracleConnector",
    "tasks.max" : "1",
    "database.server.name" : "server1",
    "database.hostname" : "<oracle ip>",
    "database.port" : "1521",
    "database.user" : "c##xstrm",
    "database.password" : "xs",
    "database.dbname" : "ORCLCDB",
    "database.pdb.name" : "ORCLPDB1",
    "database.out.server.name" : "dbzxout",
    "database.history.kafka.bootstrap.servers" : "kafka:9092",
    "database.history.kafka.topic": "schema-changes.inventory"
  }
}

Selecting the adapter

Debezium provides multiple ways to ingest change events from Oracle. By default Debezium uses the XStream API but this isn’t always applicable for every installation.

The following example configuration illustrates that by adding the database.connection.adapter, the connector can be toggled to use the LogMiner implementation.

{
    "name": "inventory-connector",
    "config": {
        "connector.class" : "io.debezium.connector.oracle.OracleConnector",
        "tasks.max" : "1",
        "database.server.name" : "server1",
        "database.hostname" : "<oracle ip>",
        "database.port" : "1521",
        "database.user" : "c##xstrm",
        "database.password" : "xs",
        "database.dbname" : "ORCLCDB",
        "database.pdb.name" : "ORCLPDB1",
        "database.out.server.name" : "dbzxout",
        "database.history.kafka.bootstrap.servers" : "kafka:9092",
        "database.history.kafka.topic": "schema-changes.inventory"
        "database.connection.adapter": "logminer"
    }
}

Connector Properties

The following configuration properties are required unless a default value is available.

column.mask.hash.SHA-256.with.salt.CzQMA0cB5K = inventory.orders.customerName, inventory.shipment.customerName

Monitoring

The Debezium Oracle connector has three metric types in addition to the built-in support for JMX metrics that Zookeeper, Kafka, and Kafka Connect have.

• snapshot metrics; for monitoring the connector when performing snapshots

• streaming metrics; for monitoring the connector when processing change events

• logminer metrics; additional metrics captured when using the LogMiner adpter to process change events

• schema history metrics; for monitoring the status of the connector’s schema history

Please refer to the monitoring documentation for details of how to expose these metrics via JMX.

Snapshot Metrics

The MBean is debezium.oracle:type=connector-metrics,context=snapshot,server=*<database.server.name>*.

Streaming Metrics

The MBean is debezium.oracle:type=connector-metrics,context=streaming,server=*<database.server.name>*.

LogMiner Metrics

The MBean is debezium.oracle:type=connector-metrics,context=log-miner,server=*<database.server.name>*.

Schema History Metrics

The MBean is debezium.mysql:type=connector-metrics,context=schema-history,server=*<database.server.name>*.

Behavior when things go wrong

Debezium is a distributed system that captures all changes in multiple upstream databases; it never misses or loses an event. When the system is operating normally or being managed carefully then Debezium provides exactly once delivery of every change event record.

If a fault does happen then the system does not lose any events. However, while it is recovering from the fault, it might repeat some change events. In these abnormal situations, Debezium, like Kafka, provides at least once delivery of change events.

The rest of this section describes how Debezium handles various kinds of faults and problems.

ORA-25191 - Cannot reference overflow table of an index-organized table

Oracle may issue this error during the snapshot phase when encountering an index-organized table (IOT). This error means that the connector has attempted to execute an operation that must be executed against the parent index-organized table that contains the specified overflow table.

To resolve this, the IOT name used in the SQL operation should be replaced with the parent index-organized table name. To determine the parent index-organized table name, use the following SQL:

SELECT IOT_NAME
  FROM DBA_TABLES
 WHERE OWNER='<tablespace-owner>'
   AND TABLE_NAME='<iot-table-name-that-failed>'

The connector’s table.include.list or table.exclude.list configuration options should then be adjusted to explicitly include or exclude the appropriate tables to avoid the connector from attempting to capture changes from the child index-organized table.