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https://github.com/privatevoid-net/nix-super.git
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975b0b52e7
Without the change any CA deletion triggers linear scan on large
RealisationsRefs table:
sqlite>.eqp full
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SCAN RealisationsRefs
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
With the change it gets turned into a lookup:
sqlite> CREATE INDEX IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SEARCH RealisationsRefs USING INDEX IndexRealisationsRefsRealisationReference (realisationReference=?)
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
41 lines
1.8 KiB
SQL
41 lines
1.8 KiB
SQL
-- Extension of the sql schema for content-addressed derivations.
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-- Won't be loaded unless the experimental feature `ca-derivations`
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-- is enabled
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create table if not exists Realisations (
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id integer primary key autoincrement not null,
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drvPath text not null,
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outputName text not null, -- symbolic output id, usually "out"
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outputPath integer not null,
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signatures text, -- space-separated list
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foreign key (outputPath) references ValidPaths(id) on delete cascade
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);
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create index if not exists IndexRealisations on Realisations(drvPath, outputName);
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-- We can end-up in a weird edge-case where a path depends on itself because
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-- it’s an output of a CA derivation, that happens to be the same as one of its
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-- dependencies.
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-- In that case we have a dependency loop (path -> realisation1 -> realisation2
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-- -> path) that we need to break by removing the dependencies between the
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-- realisations
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create trigger if not exists DeleteSelfRefsViaRealisations before delete on ValidPaths
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begin
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delete from RealisationsRefs where realisationReference in (
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select id from Realisations where outputPath = old.id
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);
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end;
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create table if not exists RealisationsRefs (
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referrer integer not null,
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realisationReference integer,
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foreign key (referrer) references Realisations(id) on delete cascade,
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foreign key (realisationReference) references Realisations(id) on delete restrict
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);
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-- used by deletion trigger
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create index if not exists IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
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-- used by QueryRealisationReferences
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create index if not exists IndexRealisationsRefs on RealisationsRefs(referrer);
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-- used by cascade deletion when ValidPaths is deleted
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create index if not exists IndexRealisationsRefsOnOutputPath on Realisations(outputPath);
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