Tell HN: Citus is 100% open source now

Re:Tell HN: Citus is 100% open source now by bombcar on Friday September 02, 2022 @02:22PM (#32694118)

SELECT causing changes to things makes me feel weird inside.

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Re:Tell HN: Citus is 100% open source now by pcthrowaway on Friday September 02, 2022 @02:23PM (#32694131)

That's how every Postgres extension works (e.g. Timescale, PostGIS, etc.)

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Re:Tell HN: Citus is 100% open source now by firloop on Friday September 02, 2022 @02:33PM (#32694254)

Not just Postgres extensions, most of Postgres’ own administrative functions can be triggered in SELECT statements. e.g. pg_terminate_backend()

https://www.postgresql.org/docs/current/functions-admin.html

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Re:Tell HN: Citus is 100% open source now by yjftsjthsd-h on Saturday September 03, 2022 @12:28PM (#32703449)

To be quite clear, that always felt weird to me as well - something to the effect of "I thought SELECT was for reading data; why am I using it to create a replica?"

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Re:Tell HN: Citus is 100% open source now by kaveet on Friday September 02, 2022 @02:28PM (#32694192)

  DO $$ BEGIN
      PERFORM rebalance_table_shards();
  END $$;

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Re:Tell HN: Citus is 100% open source now by quickthrower2 on Friday September 02, 2022 @02:25PM (#32694157)

SELECT is a bit like return?

return 6;

return x++;

or even

return (exit(0));

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Re:Tell HN: Citus is 100% open source now by colejohnson66 on Friday September 02, 2022 @02:28PM (#32694184)

I think GP is saying they view SELECT as a "pure" function. A pure function doesn't modify state, so neither should SELECT.

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Re:Tell HN: Citus is 100% open source now by bombcar on Friday September 02, 2022 @02:33PM (#32694248)

Yeah, from limited experience with SQL "SELECT is safe" (assuming no weirdness in sub functions or commands) but that's clearly not always the case.

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