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I am in the process of migrating our AWS RDS postgresql from one account to another with zero downtime. I am going with pg_dump/pg_restore + AWS CDC for ongoing replication.

I am looking for a way to generate and compare checksum to make sure no differences in data or corruption.

Q1: Is it possible to generate checksum on the database level rather than table level?

Q2: OR doing a select count(*) on all the tables in source/target is better?

when there is no downtime, data changes will be coming in the source during this process and i am afraid this will affect the checksum or rowcount comparison. Please advise

2 Answers 2

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you can't achieve zero downtime migration with pg_dump. writes that happen after the dump begins and before the restore completes and you cut-over to the new database will be lost.

What you want is log shipping, use that to build a read-only replica of thew RDS server and then cut over to that once the replica is stable.

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  • Hi Jasen, to avoid loss of data, I am going to use CDC recovery checkpoint to replay the messages to target. Is this different than you mentioned "log shipping". can you share some documentations for this
    – Falcon
    Sep 19, 2022 at 0:35
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If your tables have PKs (which is a requirement for CDC), then you can enable DMS validation on your CDC-only task. Here are some [AWS DMS docs][1] on their validation. [1]: https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Validating.html

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  • While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review Sep 11, 2023 at 19:52

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