nix-super/src/libstore/ca-specific-schema.sql
Sergei Trofimovich 975b0b52e7 ca: add sqlite index on RealisationsRefs(realisationReference)
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=?)
2022-04-21 10:06:39 +02:00

41 lines
1.8 KiB
SQL
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

-- Extension of the sql schema for content-addressed derivations.
-- Won't be loaded unless the experimental feature `ca-derivations`
-- is enabled
create table if not exists Realisations (
id integer primary key autoincrement not null,
drvPath text not null,
outputName text not null, -- symbolic output id, usually "out"
outputPath integer not null,
signatures text, -- space-separated list
foreign key (outputPath) references ValidPaths(id) on delete cascade
);
create index if not exists IndexRealisations on Realisations(drvPath, outputName);
-- We can end-up in a weird edge-case where a path depends on itself because
-- its an output of a CA derivation, that happens to be the same as one of its
-- dependencies.
-- In that case we have a dependency loop (path -> realisation1 -> realisation2
-- -> path) that we need to break by removing the dependencies between the
-- realisations
create trigger if not exists DeleteSelfRefsViaRealisations before delete on ValidPaths
begin
delete from RealisationsRefs where realisationReference in (
select id from Realisations where outputPath = old.id
);
end;
create table if not exists RealisationsRefs (
referrer integer not null,
realisationReference integer,
foreign key (referrer) references Realisations(id) on delete cascade,
foreign key (realisationReference) references Realisations(id) on delete restrict
);
-- used by deletion trigger
create index if not exists IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
-- used by QueryRealisationReferences
create index if not exists IndexRealisationsRefs on RealisationsRefs(referrer);
-- used by cascade deletion when ValidPaths is deleted
create index if not exists IndexRealisationsRefsOnOutputPath on Realisations(outputPath);