Serve sorted searches from an index, and page past an id of 0 (fkie-cad/mcritweb#59) - #162
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Serve sorted searches from an index, and page past an id of 0 (fkie-cad/mcritweb#59)#162r0ny123 wants to merge 1 commit into
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A search sorted by anything but the id had no index to be served from: the planner filtered on the search field and then sorted every matching document in memory (a blocking SORT stage on every such query, on functions the whole filtered set), which is the ~10x reported in fkie-cad/mcritweb#59. Each field the results can be sorted by now carries a compound (field, id) index; the tie-break follows the direction of the sort field, so the same index is walked backwards for the descending order instead of needing a second one. The plan for every sortable field is LIMIT -> FETCH -> IXSCAN afterwards, which a mongo-backed test asserts. As with the v1.6.2 indexes, the first start after upgrading builds them. Paging through a sorted listing also stopped early whenever a page ended on id 0: the forward cursor was built behind `if last_element_key:`, which is False for function 0, sample 0 and the unknown family 0. It is `is not None` now, with a test that pages a listing to the end in both directions.
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Closes fkie-cad/mcritweb#59 (labelled
mcrit): searches sorted by anything but the id had no index to be served from.What changed
_ensureIndexAndUnknownFamilycreates a compound(field, id)index for every field the search results can be sorted by in MCRITweb: familiesfamily_name,num_samples,num_library_samples,num_functions; samplesfamily_id,family,filename,version,bitness,sha256,statistics.num_functions; functionsfamily_id,sample_id,function_name,offset,num_instructions,num_blocks. As with the v1.6.2 indexes, the first start after upgrading builds them._get_sort_data). The order stays total and deterministic, and one index serves the descending order by being walked backwards; with(field asc, id asc)and a(field desc, id asc)sort no single index could.if last_element_key:, which is False for function 0, sample 0 and the unknown family 0. It isis not Nonenow. The details are in the commit message and the test.Measured
explain()on a real database, filterfunction_nameregex, sortnum_blocks/offset/function_name(functions),family(samples),num_samples(families), both directions:SORT → FETCH → IXSCAN(blocking in-memory sort of every filtered document)LIMIT → FETCH → IXSCAN(index order, stops at the limit)A mongo-backed test asserts the indexes exist and that the plan for a sorted search has no
SORTstage; another pages a listing to the end in both directions on the memory backend.ruff,tyand the full suite pass.