IBM Db2

IBM Db2 (LUW) sources are read through SQL replication (ASN) change-data tables, not log-tailing. Db2 has no free, unlicensed equivalent of Postgres logical decoding or MySQL's binlog — continuous log capture is only available through the separately licensed InfoSphere CDC / Q Replication. Fabric instead polls the CD tables that Db2's own Capture program maintains, ordered by (IBMSNAP_COMMITSEQ, IBMSNAP_INTENTSEQ).

Supported deployments

Db2 on Linux, UNIX, and Windows (LUW), self-managed. The ASN Capture program has to be running on the source instance — Fabric refuses to start without it — so a Db2 deployment that does not expose it cannot be used as a source.

Prerequisites

ASN capture and CD tables must already exist

Fabric does not provision replication for you. Before adding a Db2 source, an administrator runs the ASNCLP capture setup (or the Replication Center) for each table you plan to sync:

asnclp SQL -SOURCEDB mydb -TARGETDB mydb -USER db2inst1 -PASSWORD ...
SET SERVER CAPTURE;
ADD TABLE (SCHEMA."CUSTOMERS")
  CHANGE KEY (ID)
  CAPTURE ID SPECIFIED VALUE (1);
GENERATE SCRIPT 'setup.sql';
RUN SCRIPT 'setup.sql';

This provisions a CD table (e.g. ASN.CDC_CUSTOMERS) and a row in ASN.IBMSNAP_REGISTER for each source table. A selected table with no registration row is refused by name — Fabric resolves the CD table via that registry rather than guessing a naming convention.

The capture program must be running

The ASN Capture program is what actually fills the CD tables from the Db2 recovery log. Fabric checks ASN.IBMSNAP_CAPPARMS.CAPTURE_STATE at preflight and refuses to start if capture is stopped:

asncap CAPTURE_SCHEMA=ASN CAPTURE_SERVER=mydb &

A read-only login

Fabric's login needs SELECT on the ASN schema's CD tables and register table, and on the base tables for snapshot and schema discovery:

GRANT SELECT ON SCHEMA ASN TO USER fabric_cdc;
GRANT SELECT ON TABLE SCHEMA.CUSTOMERS TO USER fabric_cdc;

Network and driver

The runner reaches host:50000 (Db2's default port) using the ibm_db driver bundled with Fabric. There is no ODBC DSN to configure — the connector builds the connection string directly from the source's host, port, database, and credentials.

Connection fields

The shared snapshot and commit fields apply on top of these — see the source overview.

How it replicates

• Fabric resolves each selected table's CD table by looking it up in ASN.IBMSNAP_REGISTER, then polls it with a bookmark on (IBMSNAP_COMMITSEQ, IBMSNAP_INTENTSEQ), ordered by both columns — the second field breaks ties within one commit, since a single transaction can change several rows.
• IBMSNAP_OPERATION (I/U/D) maps directly to insert/update/delete; unlike SQL Server's CT tables, a Db2 CD row is already one row per change, with no update pairs to collapse.
• The snapshot captures the current maximum IBMSNAP_COMMITSEQ before scanning and checkpoints per-table progress, so a mid-snapshot crash resumes under the same mark instead of skipping changes.
• Snapshot chunking uses a single-column unique or primary-key index; a table with no safe key falls back to one unchunked pass.

Gotchas