forked from lix-project/lix
Sergei Trofimovich
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=?)
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| .. | ||
| build-remote | ||
| libcmd | ||
| libexpr | ||
| libfetchers | ||
| libmain | ||
| libstore | ||
| libutil | ||
| nix | ||
| nix-build | ||
| nix-channel | ||
| nix-collect-garbage | ||
| nix-copy-closure | ||
| nix-env | ||
| nix-instantiate | ||
| nix-store | ||
| resolve-system-dependencies | ||
| toml11 | ||