{ "schemaVersion": 1, "slug": "hdf5-vds-dependencies", "title": "HDF5 virtual dataset dependency observations", "summary": "Eight controlled cases distinguish a byte-identical virtual dataset file from complete and correctly resolved source arrays.", "published": "2026-10-18", "updated": "2026-10-18", "generatedAt": "2026-10-17T21:21:32.318946+00:00", "evidenceType": "measured-api-behavior", "license": "CC0-1.0 for Hesela's original harness and observations; upstream libraries and documents retain their licenses.", "licenseUrl": "https://creativecommons.org/publicdomain/zero/1.0/", "humanPage": "https://hesela.com/analyses/hdf5-virtual-datasets-missing-sources/", "sourceUrl": "https://hesela.com/analyses/hdf5-virtual-datasets-missing-sources/", "downloadPath": "/data/datasets/hdf5-vds-dependencies.csv", "codePath": "/research/hdf5-vds.py", "rawPath": "/research/hdf5-vds.json", "requirementsPath": "/research/hdf5-vds-requirements.txt", "generatorPath": "/scripts/build-hdf5-vds.mjs", "rowCount": 24, "columns": [ { "name": "repetition", "type": "integer", "description": "One-based repeat on the same host, not an independent reliability trial." }, { "name": "case", "type": "string", "description": "Controlled source-availability or resolution change." }, { "name": "readerExitCode", "type": "integer", "description": "Final reader process exit code; zero means it completed all three dataset reads." }, { "name": "viewHashMatches", "type": "boolean", "description": "VDS file SHA-256 equals its pre-change hash." }, { "name": "colocatedSourceHashesMatch", "type": "boolean", "description": "Both named source files beside the VDS match baseline hashes; not a resolver audit." }, { "name": "prefixOverride", "type": "boolean", "description": "Reader received a controlled HDF5_VDS_PREFIX containing a replacement b.h5." }, { "name": "defaultValues", "type": "JSON", "description": "Full fixed-shape VDS array with default fill value zero; dimensionless synthetic integers." }, { "name": "sentinelValues", "type": "JSON", "description": "Full fixed-shape VDS array with explicit fill value -999." }, { "name": "materializedValues", "type": "JSON", "description": "Ordinary array copied while baseline sources were present, before any mutation." } ], "rows": [ { "repetition": 1, "case": "present", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "missing-file", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "missing-dataset", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "substituted-source", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "legitimate-zero", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ] }, { "repetition": 1, "case": "relocated-vds-only", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 0, 0, 0 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ -999, -999, -999 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "relocated-complete", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 1, "case": "prefix-override", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": true, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "present", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "missing-file", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "missing-dataset", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "substituted-source", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "legitimate-zero", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ] }, { "repetition": 2, "case": "relocated-vds-only", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 0, 0, 0 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ -999, -999, -999 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "relocated-complete", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 2, "case": "prefix-override", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": true, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "present", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "missing-file", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "missing-dataset", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "substituted-source", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "legitimate-zero", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 0, 0, 0 ] ] }, { "repetition": 3, "case": "relocated-vds-only", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": false, "prefixOverride": false, "defaultValues": [ [ 0, 0, 0 ], [ 0, 0, 0 ] ], "sentinelValues": [ [ -999, -999, -999 ], [ -999, -999, -999 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "relocated-complete", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": false, "defaultValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] }, { "repetition": 3, "case": "prefix-override", "readerExitCode": 0, "viewHashMatches": true, "colocatedSourceHashesMatch": true, "prefixOverride": true, "defaultValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "sentinelValues": [ [ 11, 12, 13 ], [ 91, 92, 93 ] ], "materializedValues": [ [ 11, 12, 13 ], [ 21, 22, 23 ] ] } ], "method": "Eight fresh private fixtures per repetition. Each VDS maps two three-element int32 arrays into fixed (2,3) shape, once with default fill and once with -999. Every final observation uses a fresh Python process and empty working directory; HDF5_VDS_PREFIX is unset except in the named override case. All handles close before mutations. A separately materialized baseline is a control.", "environment": { "python": "3.12.3", "kernel": "6.8.0-146-generic", "machine": "x86_64", "h5py": "3.15.0", "hdf5": "1.14.6", "numpy": "2.3.3", "driver": "sec2", "libver": "v110" }, "limits": [ "Synthetic integers without physical units; not a scientific instrument dataset.", "One host and pinned library build; repetitions are not independent reliability trials.", "No power failure, concurrent writer, corrupt source, permissions fault or network filesystem test.", "Fixed relative filenames only; no unlimited selections, printf mappings, nested VDS or external links.", "Colocated hashes cover named files beside the VDS, not the library's complete resolution environment.", "The materialized control preserves this array only, not every group, attribute or scientific dependency." ], "hashes": { "sourceSha256": "be6d49365040507c986d81db134d064373255a9f8724128a20800b74e1596309", "requirementsSha256": "1562cd45452194a553bb9af837d31e54fb70bb0f83af365693aaa6c672957e1a", "rawSha256": "e7569794af33b019869027be5aae1496e668f9d0ad49dedf91d06a842dd15dea", "csvSha256": "934a33d5f77a983c6586a48ebba3f1954fb2efb7ebe5faaf4511f52111b28669" }, "citations": [ { "id": "h5py-vds", "title": "h5py 3.15.0: Virtual Datasets", "url": "https://docs.h5py.org/en/3.15.0/vds.html", "accessed": "2026-10-17" }, { "id": "h5-vds", "title": "The HDF Group: Introduction to the Virtual Dataset", "url": "https://support.hdfgroup.org/documentation/hdf5/latest/_v_d_s_t_n.html", "accessed": "2026-10-17" }, { "id": "h5-properties", "title": "The HDF Group: H5Pset_virtual source-file resolution and H5Pset_fill_value", "url": "https://support.hdfgroup.org/documentation/hdf5/latest/group___d_c_p_l.html", "accessed": "2026-10-17" }, { "id": "h5py-dataset", "title": "h5py 3.15.0: Dataset.is_virtual and Dataset.virtual_sources", "url": "https://docs.h5py.org/en/3.15.0/high/dataset.html", "accessed": "2026-10-17" } ] }