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54f5c5150f
Commit 04ae11f62e removed some broken
code to apply the scan/join target to partial paths, but its theory
that this processing step is totally unnecessary turns out to be wrong.
Put similar code back again, but this time, check for parallel-safety
and avoid in-place modifications to paths that may already have been
used as part of some other path.
(This is not an entirely elegant solution to this problem; it might
be better, for example, to postpone generate_gather_paths for the
topmost scan/join rel until after the scan/join target has been
applied. But this is not the time for such redesign work.)
Amit Kapila and Robert Haas
52 lines
1.5 KiB
PL/PgSQL
52 lines
1.5 KiB
PL/PgSQL
--
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-- PARALLEL
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--
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create or replace function parallel_restricted(int) returns int as
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$$begin return $1; end$$ language plpgsql parallel restricted;
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-- Serializable isolation would disable parallel query, so explicitly use an
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-- arbitrary other level.
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begin isolation level repeatable read;
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-- setup parallel test
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set parallel_setup_cost=0;
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set parallel_tuple_cost=0;
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set max_parallel_workers_per_gather=4;
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explain (costs off)
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select count(*) from a_star;
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select count(*) from a_star;
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-- test that parallel_restricted function doesn't run in worker
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alter table tenk1 set (parallel_workers = 4);
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explain (verbose, costs off)
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select parallel_restricted(unique1) from tenk1
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where stringu1 = 'GRAAAA' order by 1;
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-- test parallel plan when group by expression is in target list.
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explain (costs off)
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select length(stringu1) from tenk1 group by length(stringu1);
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select length(stringu1) from tenk1 group by length(stringu1);
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-- test that parallel plan for aggregates is not selected when
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-- target list contains parallel restricted clause.
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explain (costs off)
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select sum(parallel_restricted(unique1)) from tenk1
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group by(parallel_restricted(unique1));
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set force_parallel_mode=1;
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explain (costs off)
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select stringu1::int2 from tenk1 where unique1 = 1;
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do $$begin
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-- Provoke error, possibly in worker. If this error happens to occur in
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-- the worker, there will be a CONTEXT line which must be hidden.
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perform stringu1::int2 from tenk1 where unique1 = 1;
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exception
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when others then
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raise 'SQLERRM: %', sqlerrm;
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end$$;
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rollback;
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