Db2 to PostgreSQL
real-time replication
TwinCommit replicates IBM Db2 to PostgreSQL in real time by reading the Db2 transaction log and applying every committed change exactly once and in commit order. Use it to migrate or continuously mirror Db2 into PostgreSQL with zero downtime, with no triggers or capture tables on the source.
Db2
log reader
commit-ordered · exactly-once
PostgreSQL
native writer
How capture works on Db2
TwinCommit reads the Db2 recovery log through the native log read API and decodes row images itself. No SQL Replication, no Q Replication, no CD tables, no triggers and no capture agents are installed on the source.
Prerequisites
- ✓Archive logging enabled (LOGARCHMETH1)
- ✓DATA CAPTURE CHANGES on each replicated table
- ✓A primary key or unique index on each replicated table
- ✓DBADM (or SYSADM) for the capture user
How apply works on PostgreSQL
Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Requirements
- ✓wal_level = logical
- ✓REPLICATION privilege
- ✓Primary key or REPLICA IDENTITY FULL
Setup
Set up Db2 → PostgreSQL in four steps
- 1
Prepare Db2
Run twincommit check. It verifies archive logging enabled (logarchmeth1) and the other prerequisites, and prints the exact fix for anything missing.
- 2
Point at PostgreSQL
Add a target block for PostgreSQL. TwinCommit can generate target DDL with twincommit ddl -apply.
- 3
Snapshot
twincommit snapshot copies each table under a brief share lock and records the exact log position.
- 4
Stream
twincommit run streams every committed change from that position, exactly once and in commit order.
source:
type: db2
database: PRODDB
user: ${SRC_USER}
password: ${SRC_PASSWORD}
target:
type: postgres
dsn: ${PG_DSN}
tables:
- source: SALES.ORDERS
- source: SALES.ORDER_LINES
exclude_columns: [INTERNAL_NOTES]Db2 to PostgreSQL replication FAQ
How does TwinCommit replicate Db2 to PostgreSQL?
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TwinCommit reads changes from the Db2 transaction log, buffers them per transaction, and applies each committed transaction to PostgreSQL in commit order. Binary COPY into staging plus INSERT … ON CONFLICT, with the checkpoint in the same transaction.
Does Db2 to PostgreSQL replication need triggers or capture tables?
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No. TwinCommit reads the Db2 log directly and creates no objects in the source database.
Is Db2 to PostgreSQL replication exactly-once?
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Yes. TwinCommit commits its checkpoint in the same PostgreSQL transaction as the data, so a crash or restart never loses or duplicates a transaction.
What Db2 versions are supported?
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Db2 LUW 11.1, 11.5, 12.1 · Db2 for z/OS 12 and 13 · Db2 on Cloud (target).
Stream Db2 to PostgreSQL today.
Download the free Developer edition, or have one of our replication engineers walk you through a migration plan.