Start one background worker on first DuckDB query #544
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JelteF
requested changes
Mar 7, 2025
src/pgduckdb_background_worker.cpp
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| @@ -252,13 +341,13 @@ InitBackgroundWorker(void) { | |||
| #else | |||
| ShmemRequest(); | |||
| #endif | |||
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I think this should also be in InitBackgroundWorkersShmem. And I think that's probably the reason why you now needed the BgwShmemStruct->lock in TriggerActivity. So if you move this code I think you can remove the changes to TriggerActivity
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I'm actually still getting the segfault when moving that around. Though I agree, it makes more sense to put it there.
| void | ||
| InitBackgroundWorker(void) { | ||
| InitBackgroundWorkersShmem(void) { |
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| InitBackgroundWorkersShmem(void) { | |
| InitBackgroundWorkerShmem(void) { |
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The s was intentional - it does initialize memory of all BG workers that may be spawned (when there are one per DB). Technically it's not in this PR, so maybe I can rename later?
JelteF
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Mar 10, 2025
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Mar 10, 2025
JelteF
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Apr 22, 2025
Following #544, remove the `duckdb.motherduck_postgres_database` GUC parameter and start a background worker for each PG database (*) For another database to synchronize with the BGW to work: * extension must be created: `CREATE EXTENSION pg_duckdb;` * `duckdb` should be able to write in `public` schema: `GRANT ALL ON SCHEMA public to duckdb;`
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Up until now, we were starting the background worker as part of the extension.
The problem with this approach is that it imposes a unique worker, and thus cannot updated multiple database.
In preparation to have one BGW per database, this PR triggers the start of a background worker when
IsExtensionRegisteredis called and the cache is populated.We've prevented potential race conditions that would cause two bgw to start by checking a lock on a temporary file.
Note: a following PR will actually start one BGW per database