brianmcgee/nix-cache-dataset

Nix Cache Dataset

This repository contains several datasets relating to the contents of https://cache.nixos.org:

Getting started

To make it easier to explore the datasets, a Nix devshell is provided in shell.nix. To enter it, run

❯ nix develop -f shell.nix 

[brian@saturn:~/Development/com/github/numtide/nix-cache-dataset]$

If you are a Direnv user, you can also run direnv allow to automatically load the devshell:

❯ direnv allow 
direnv: loading ~/Development/com/github/numtide/nix-cache-dataset/.envrc                                                                                                                                                                           
direnv: using nix
direnv: nix-direnv: Using cached dev shell
direnv: export +AR +AS +CC +CONFIG_SHELL +CXX +HOST_PATH +IN_NIX_SHELL +LD +NIX_BINTOOLS +NIX_BINTOOLS_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu +NIX_BUILD_CORES +NIX_CC +NIX_CC_WRAPPER_TARGET_HOST_x86_64_unknown_linux_gnu +NIX_CFLAGS_COMPILE +NIX_ENFORCE_NO_NATIVE +NIX_HARDENING_ENABLE +NIX_LDFLAGS +NIX_STORE +NM +OBJCOPY +OBJDUMP +RANLIB +READELF +SIZE +SOURCE_DATE_EPOCH +STRINGS +STRIP +__structuredAttrs +buildInputs +buildPhase +builder +cmakeFlags +configureFlags +depsBuildBuild +depsBuildBuildPropagated +depsBuildTarget +depsBuildTargetPropagated +depsHostHost +depsHostHostPropagated +depsTargetTarget +depsTargetTargetPropagated +doCheck +doInstallCheck +dontAddDisableDepTrack +mesonFlags +name +nativeBuildInputs +out +outputs +patches +phases +preferLocalBuild +propagatedBuildInputs +propagatedNativeBuildInputs +shell +shellHook +stdenv +strictDeps +system ~PATH ~XDG_DATA_DIRS

brian@saturn ~/..../nix-cache-dataset   main* ⇡
❯  

The devshell contains a duckdb command which is pre-configured to load some helpful utility functions which reside in ./duckdb/init.sql:

• nixbase32 which converts a fixed-size byte[20] column into nixbase32
• narURL which recovers the URL of a NAR file from it's file_hash and compression columns.

Both are necessary when introspecting any of the narinfo related datasets as their schema was optimized to reduce file sizes.

Contents

The primary datasets below were compiled with Narwal.

datasets/inventory-2026-01-06T01-13Z.parquet

This is a complete inventory of the S3 Bucket which backs the cache as of 2026-01-06T01:13Z and provided by the S3 Inventory Service. It has the following schema and is ordered by key:

❯ duckdb -c "describe select * from 'datasets/inventory-2026-01-06T01-13Z.parquet'" 
┌────────────────────┬──────────────────────────┬─────────┬─────────┬─────────┬─────────┐
│    column_name     │       column_type        │  null   │   key   │ default │  extra  │
│      varchar       │         varchar          │ varchar │ varchar │ varchar │ varchar │
├────────────────────┼──────────────────────────┼─────────┼─────────┼─────────┼─────────┤                                                                                                                                                           
│ key                │ VARCHAR                  │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                           
│ size               │ BIGINT                   │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                           
│ last_modified_date │ TIMESTAMP WITH TIME ZONE │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                           
│ e_tag              │ VARCHAR                  │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                           
│ storage_class      │ VARCHAR                  │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                           
└────────────────────┴──────────────────────────┴─────────┴─────────┴─────────┴─────────┘   

Here is the first 10 entries:

❯ duckdb -c "select * from 'datasets/inventory-2026-01-06T01-13Z.parquet' limit 10"
┌──────────────────────────────────────────┬───────┬──────────────────────────┬──────────────────────────────────┬───────────────┐
│                   key                    │ size  │    last_modified_date    │              e_tag               │ storage_class │
│                 varchar                  │ int64 │ timestamp with time zone │             varchar              │    varchar    │
├──────────────────────────────────────────┼───────┼──────────────────────────┼──────────────────────────────────┼───────────────┤                                                                                                                  
│ .well-known/pki-validation/gsdv.txt      │   101 │ 2018-09-07 09:35:54+01   │ dcdfef6f1cdfeae2d2c9de7dab84292a │ STANDARD      │                                                                                                                  
│ 000003nzgismzlipaq0jnchpz65d65z7.ls      │  1228 │ 2024-06-21 17:17:36+01   │ bf47b9ab2ea7a795d15107d4dcf64697 │ STANDARD      │                                                                                                                  
│ 000003nzgismzlipaq0jnchpz65d65z7.narinfo │  1452 │ 2024-06-21 17:17:37+01   │ 34997acded08172170eb1a4cde9456d1 │ STANDARD      │                                                                                                                  
│ 00000c8rdrjqkdxjpm5wrhl6sspapbmn.ls      │    97 │ 2019-11-06 19:35:06+00   │ ae368bafcfb9e5632acc57acf4f2a325 │ STANDARD      │                                                                                                                  
│ 00000c8rdrjqkdxjpm5wrhl6sspapbmn.narinfo │   905 │ 2019-11-06 19:35:06+00   │ 0bf1c5c76cf15dd07c8c79eca27ebff4 │ STANDARD      │                                                                                                                  
│ 00000in9ndrbpshcibwfgsygx0xq069g.ls      │   329 │ 2025-11-07 18:40:26+00   │ f817f1b476fe0cb82ac2f5dbc19be620 │ STANDARD      │                                                                                                                  
│ 00000in9ndrbpshcibwfgsygx0xq069g.narinfo │   732 │ 2025-11-07 18:40:28+00   │ 4037fbf8ab5484847756f0839c2c7245 │ STANDARD      │                                                                                                                  
│ 00000jipsrr2nfgn36w04xg2z6hnr7y0.ls      │   323 │ 2024-01-06 07:48:26+00   │ 8a3bad8cb3795080ccd636ef212c1878 │ STANDARD      │                                                                                                                  
│ 00000jipsrr2nfgn36w04xg2z6hnr7y0.narinfo │   523 │ 2024-01-06 07:48:27+00   │ 997c5c9a6911bfadd7efcb9f845a4082 │ STANDARD      │                                                                                                                  
│ 00000lkv8yz6bsccrp03ppq71mzjdcpv.ls      │   396 │ 2022-05-10 03:33:54+01   │ 3284e9e9e5ae0a2562640e1f20af395d │ STANDARD      │                                                                                                                  
├──────────────────────────────────────────┴───────┴──────────────────────────┴──────────────────────────────────┴───────────────┤                                                                                                                  
│ 10 rows                                                                                                              5 columns │                                                                                                                  
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ 

`datasets/narinfos-2026-01-06T01-13Z.parquet``

This is a complete download of all .narinfo files within the S3 bucket as of 2026-01-06T01:13Z. It has the following schema:

❯ duckdb -c "describe select * from 'datasets/narinfos-2026-01-06T01-13Z.parquet' 
┌───────────────────────────────┬─────────────┬─────────┬─────────┬─────────┬─────────┐
│          column_name          │ column_type │  null   │   key   │ default │  extra  │
│            varchar            │   varchar   │ varchar │ varchar │ varchar │ varchar │
├───────────────────────────────┼─────────────┼─────────┼─────────┼─────────┼─────────┤                                                                                                                                                             
│ hash                          │ BLOB        │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ pname                         │ VARCHAR     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ compression                   │ VARCHAR     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ file_hash                     │ BLOB        │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ file_size                     │ UBIGINT     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ nar_hash                      │ BLOB        │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ nar_size                      │ UBIGINT     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ references                    │ BLOB[]      │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ deriver                       │ BLOB        │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ deriver_pname                 │ VARCHAR     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ system                        │ VARCHAR     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ signature_domains             │ VARCHAR[]   │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ signature_values              │ BLOB[]      │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ ca_algo                       │ VARCHAR     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ ca_hash                       │ BLOB        │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
│ quirk_references_out_of_order │ BOOLEAN     │ YES     │ NULL    │ NULL    │ NULL    │                                                                                                                                                             
├───────────────────────────────┴─────────────┴─────────┴─────────┴─────────┴─────────┤                                                                                                                                                             
│ 16 rows                                                                   6 columns │                                                                                                                                                             
└─────────────────────────────────────────────────────────────────────────────────────┘   

The schema is the same as the contents of a .narinfo file with some notable differences:

• StorePath has been split into hash and pname, with the /nix/store/ prefix omitted.
• In addition, hash has been decoded from its original 32-byte nixbase32 format into a 20-byte fixed-size byte[20] column to save space. As mentioned in Getting Started, there is a nixbase32 utility function for duckdb which can be used to convert it back into it's original format.
• URL is not included. Instead, it can be recovered from the file_hash and compression columns using the narURL utility function. Again, this was to save space.
• quirk_references_out_of_order indicates whether the references column was not canonically sorted as is required by the narinfo format.

Here is an example of using both:

❯ duckdb -c " select nixbase32(hash) as hash, pname, narURL(file_hash, compression) as URL from 'datasets/narinfos-2026-01-06T01-13Z.parquet' where pname like 'nixos-%.iso' limit 10" 
┌──────────────────────────────────┬──────────────────────────────────────────────────────────────────────┬─────────────────────────────────────────────────────────────────┐
│               hash               │                                pname                                 │                               URL                               │
│             varchar              │                               varchar                                │                             varchar                             │
├──────────────────────────────────┼──────────────────────────────────────────────────────────────────────┼─────────────────────────────────────────────────────────────────┤                                                                       
│ 8s2i888nxl44dvrqkszyhm9wagx21cv8 │ nixos-21.11pre-git-aarch64-linux.iso                                 │ nar/01i2cax5rgfirdnqy3gk0fam1jxjqzydlm6fmydqcr2rppzfgpyc.nar.xz │                                                                       
│ 8s2nl0q5l0qjwj4mdh47b32abd7dkb37 │ nixos-plasma5-23.11pre525972.ace5093e36ab-x86_64-linux.iso           │ nar/03wiqhgkgbwr6lz6jlhnq9d4swjahdw32ylixshmpy25wmnhkg83.nar.xz │                                                                       
│ 8s308z464is6rbnn1wglws37bz5cxhi3 │ nixos-minimal-new-kernel-21.03pre253346.87e9b49fc78-x86_64-linux.iso │ nar/1ppngdicfkydg44hbyc6s77f40qk15a8r370a02yg06y4w7fscp3.nar.xz │                                                                       
│ 8s37vnmdg68z51s81lp7pfclkp0ljl7v │ nixos-plasma5-21.11.335288.3ddd960a3b5-x86_64-linux.iso              │ nar/04pic41qkjib69bl1yk48w5bdnb0jj4jfzljmfxsx3c9sr966m71.nar.xz │                                                                       
│ 8s4yq0kgvw7d34jzd6j256n8rhqdncag │ nixos-18.03pre-git-x86_64-linux.iso                                  │ nar/11m49i89vpm8mjq2khpiy9p4br3fkvk57nmi6narmxbih9lahg45.nar.xz │                                                                       
│ 8s4zyq65nl0d5jjd28pvm8rih78khhlx │ nixos-21.03pre-git-x86_64-linux.iso                                  │ nar/00ivaz2lwdvqcg7c64l9ikgk0njcphad4h69z2hvih7xrrzvwbb0.nar.xz │                                                                       
│ 8s5577gfk2makszs3bnpfzf8h477ywwd │ nixos-minimal-17.03.1730.dad3c2231c-i686-linux.iso                   │ nar/074d9323apli87919s8rr8rfa0javdqvk24r4siclq1ysg67gp38.nar.xz │                                                                       
│ 8s580im104kqdf873sc1bqanp5x7mvjn │ nixos-18.09pre-git-x86_64-linux.iso                                  │ nar/0nw2zmxw3bhn9ixx66n9vfhk81qvr88yh1a3dxyv1qi5xbqv8fgz.nar.xz │                                                                       
│ 8s5wj1h8hcvhiqxghlgblxnsi8lccrs7 │ nixos-graphical-25.11pre819493.4206c4cb5675-x86_64-linux.iso         │ nar/0mnwc0lpxf4hllv97gc58rd7m0rkph03cg2b35zmarq1kcd1ihq5.nar.xz │                                                                       
│ 8s616arfxnpgz8grd3rggm9ahgk5wvn7 │ nixos-minimal-19.09pre174421.b306b4cf1a9-x86_64-linux.iso            │ nar/1qxcksrfa9nv10ln5kf2mcx2jndx4hyf34x594779f0lh4rlfw68.nar.xz │                                                                       
├──────────────────────────────────┴──────────────────────────────────────────────────────────────────────┴─────────────────────────────────────────────────────────────────┤                                                                       
│ 10 rows                                                                                                                                                         3 columns │                                                                       
└───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘      

datasets/narinfos-nixos-2026-01-06T01-13Z.parquet

This is a subset of the narinfos-2026-01-06T01-13Z.parquet dataset which is attempting to identify any narinfos related to NixOS ISOs and other images which have been uploaded to the cache. These are candidates for removal from the cache as they are stored elsewhere.

It was compiled using ./duckdb/nixos-images.sql;

datasets/narinfos-nixos-images-dangling-refs-2026-01-06T01-13Z.parquet

This is a list of store paths which reference one or more of the store paths contained in datasets/narinfos-nixos-images-2026-01-06T01-13Z.parquet, which will be affected by their removal from https://cache.nixos.org.

It was compiled using bin/dangling-references.py.

datasets/buildstepoutputs-2025-12-05-17:38:30Z.csv.zst

This is a dump of the buildstepoutputs table taken from Hydra on 2025-12-05T17:38:30Z. It can be thought of as a record of every output path that Hydra has ever built and looks like this:

❯ head datasets/buildstepoutputs-2025-12-05-17:38:30Z.csv 
build,stepnr,name,path
684,2,out,/nix/store/mnkbj3aziazk2ijadn23cpwarm6bfmh8-nixos-install
683,5,out,/nix/store/172yppi4bklbs1cyh91wqwpyyfbkvgds-system-path
684,3,out,/nix/store/dxi8ij2la8in64mclyjslgs04nylcsa2-upstart-manual
685,1,out,/nix/store/isaw8s240isvg06pimbr1wj12wxs9glv-hydra-build
684,4,out,/nix/store/qcpb0179capgcyij03xk6fqhlwbafjr0-upstart-jobs
686,1,out,/nix/store/07syvqz4w8n0z3alfm4kg5i46v3wbidx-checkinstall-1.6.1
686,2,out,/nix/store/1g5nks931nirya16hmw2l1lg0jwazmsw-e2fslibs_1.39+1.40-WIP-2006.11.14+dfsg-2etch1_amd64.deb
686,3,out,/nix/store/0dgvq0q33sniq77kq9150shj0jqllzh0-file_4.17-5etch3_amd64.deb
686,4,out,/nix/store/7f03xxka0l0h623ydvqsjvqf6w1vvhzv-heimdal-1.0.2.tar.gz

datasets/inventory-not-in-buildstepoutputs-2025-12-05-17:38:30Z.parquet

This file contains a list of all the .narinfo files within datasets/inventory-2026-01-06T01-13Z.parquet (up to 2025-12-05-17:38:30Z) which do not have a corresponding entry in datasets/buildstepoutputs-2025-12-05-17:38:30Z.csv.zst.

It was compiled using ./duckdb/inventory-not-in-buildstepoutputs.sql;

Subsequently, graphs were generated using bin/graph-inventory-not-in-buildstepoutputs.py and placed in ./graphs: