CDC vs Load
DBConvert Streams has two execution modes. This page compares them side by side. For detailed setup, see the dedicated pages for each mode.
Comparison
| Load | CDC | |
|---|---|---|
| Purpose | Bounded transfer — initial load, one-time sync, filtered export | Continuous replication of ongoing row-level changes |
| Duration | Finishes when scope is complete | Runs until stopped |
| Source input | Direct table read or custom SQL query | Transactional log (binlog / WAL) |
| Source engines | MySQL, PostgreSQL, local files, S3 | MySQL, PostgreSQL only |
| Target engines | MySQL, PostgreSQL, files, S3 | MySQL, PostgreSQL, files, S3 |
| Multi-source | Yes — combine multiple connections | No — single source only |
| Custom SQL | Yes — query-driven extraction | No |
| Structure creation | Creates missing tables, indexes on target (structure options) | Creates missing tables, indexes on target |
| Captured events | Full table content at read time | INSERT, UPDATE, DELETE from source log |
| Initial existing rows | Primary purpose of the mode | Optional Initial Load + CDC for empty targets |
| Resume behavior | Re-run the bounded job when needed | Resumes from a durable checkpoint when the same config is started again |
| Source setup | Standard connection — no additional server-side configuration needed | Requires server-side changes: binlog (MySQL) or logical replication (PostgreSQL) must be enabled |
Decision flow
- Can the job finish? If you need a bounded transfer with a clear end, use Load.
- Do you need ongoing changes? If the target must stay synchronized after the initial load, evaluate CDC.
- Is your source a file or S3? Use Load — CDC requires a transactional database source.
- Do you need multiple sources? Use Load — CDC does not support multi-source streams.
- Is your source–target combination supported for CDC? Check the Capability Matrix. If not confirmed, use Load.
When unsure, start with Load. It has broader source/target coverage and requires less source-side configuration.
Common rollout
CDC now supports two initial-load patterns.
Use Initial Load + CDC when the target tables are empty and you want a single CDC run to copy existing rows before it continues with log-based changes.
Use Load first, then CDC when the initial load is a separate migration step, the target is not empty, or you need Load-only features such as custom SQL, multi-source input, files, or S3 sources.
Both patterns apply only when the source–target combination supports CDC.