Fix pg_dump for databases created with PGlite < v0.2.9

[jgoux]

I implemented a "middleware" which :

• detects if pg_dump initiated a connection through the application_name=pg_dump in the Startup message.
• listen to both client and server message to detect and patch the right query results.

The two queries we're interested in are:

• GetExtensions
• GetExtensionMembership

I looked at pg_dump code from v15 to v17 and the queries definitions are the same across all these versions so we can safely detect them.

The logic is:

• We detect the GetExtensions query
• We wait for its result from which we extract the actual oid of the vector extension and then patch it (using the oid 99999)
• We then wait for the GetExtensionMembership query
• We wait for its result and we patch it reusing the actual vector extension oid for a search/replace purpose.

Once pg_dump receives an oid > 16384 for the extensions, it will print the CREATE EXTENSION statements in the dump.

If we use pg_dump to migrate people to the new domain, we will be able to delete this middleware as everyone will be on a patched version of PGlite. 👍

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Name	Status	Preview	Comments	Updated (UTC)
postgres-new	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 1, 2024 8:05am

[jgoux]

@gregnr All comments addressed, merging! 🫡