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Add single ALP test file (216KB, covers corner cases) - #119

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Add single ALP test file (216KB, covers corner cases)#119
alamb wants to merge 5 commits into
apache:masterfrom
alamb:alamb/alp_test_data

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@alamb

@alamb alamb commented Aug 4, 2026 •
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(Draft until I validate this example some more)

Rationale

#100 from @prtkgaur and @vinooganesh at prtkgaur#1 have coverage but are also 4x larger than all the existing data files

Thus I want to create an example file that can be used by readers but is not large and still covers all the corner cases

Changes

  1. Adds a single 216 KB file created with a CLI driver based on the C++ implementation
  1. Describes the contents and rationale in data/README.md. I found the rendered preview easier to read: https://github.com/alamb/parquet-testing/blob/alamb/alp_test_data/data/README.md#alp-encoding
full file layout details 

Wrote /tmp/alp_extended.zstd.parquet (218992 bytes)

File: /tmp/alp_extended.zstd.parquet
  rows: 9032, row groups: 5, columns: 8

Column 'float_plain' (FLOAT)
  Row group 0: rows=6144 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=21005
  Row group 1: rows=1024 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=3863
  Row group 2: rows=1024 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=47
  Row group 3: rows=808 encodings=[ RLE PLAIN ] compression=zstd null_count=8 compressed_bytes=2672
  Row group 4: rows=32 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=162

Column 'double_plain' (DOUBLE)
  Row group 0: rows=6144 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=24880
  Row group 1: rows=1024 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=5882
  Row group 2: rows=1024 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=53
  Row group 3: rows=808 encodings=[ RLE PLAIN ] compression=zstd null_count=8 compressed_bytes=2376
  Row group 4: rows=32 encodings=[ RLE PLAIN ] compression=zstd null_count=0 compressed_bytes=291

Column 'float_alp_1024' (FLOAT)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=16430
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=6144
    num_vectors=6 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      6   4   11  4294966296           0     
    1      1024      6   4   11  4294966296           7      0:nan, 476:nan, 976:inf, 977:-inf, 978:-0, ...
    2      1024      6   4   11  4294966297           1      452:3.1415927410125732
    3      1024      6   4   11  4294966296           2      28:44974936064, 639:-1243432448
    4      1024      6   4   11  4294966296           512    0:-5.6894025802612305, 2:-5.7471122741699219, 4:5.2631058692932129, 6:3.063255786895752, 8:7.4240894317626953, ...
    5      1024      6   4   0   0                    1024   0:0.98619550466537476, 1:-3.7603194713592529, 2:-0.34999150037765503, 3:0.1334528774023056, 4:-2.2552545070648193, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2351
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      6   2   18  4294867362           0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=45
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      10  8   0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1186
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=800
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      800       6   4   11  4294966297           0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=237
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=32
    num_vectors=1 total_exceptions=32
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        10  10  0   0                    32     0:-7.9999998744539955e+18, 1:7.9999998744539955e+18, 2:3.2175613495004365e+18, 3:-1.428295291294974e+18, 4:74196599420485632, ...

Column 'double_alp_1024' (DOUBLE)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=22638
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=6144
    num_vectors=6 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      14  12  11  18446744073709550616 0     
    1      1024      14  12  11  18446744073709550616 7      0:nan, 476:nan, 976:inf, 977:-inf, 978:-0, ...
    2      1024      14  12  11  18446744073709550617 1      452:3.1415926535897931
    3      1024      14  12  11  18446744073709550616 2      28:44974934523.343002, 639:-1243432432.3432
    4      1024      14  12  11  18446744073709550616 512    0:-5.6894026020883821, 2:-5.7471123414096521, 4:5.2631058917995048, 6:3.0632557599260757, 8:7.4240896660071236, ...
    5      1024      14  12  0   0                    1024   0:0.98619550441899628, 1:-3.7603195733564965, 2:-0.34999150139969903, 3:0.13345287723017574, 4:-2.2552545378626987, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2355
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      16  12  18  18446744073709451682 0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=49
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      16  14  0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1190
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=800
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      800       14  12  11  18446744073709550617 0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=305
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=10 (vector_size=1024) num_elements=32
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        0   0   64  10446744073709551616 0     

Column 'float_alp_4096' (FLOAT)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=17786
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=6144
    num_vectors=2 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      4096      6   4   11  4294966296           10     1024:nan, 1500:nan, 2000:inf, 2001:-inf, 2002:-0, ...
    1      2048      6   4   11  4294966296           1536   0:-5.6894025802612305, 2:-5.7471122741699219, 4:5.2631058692932129, 6:3.063255786895752, 8:7.4240894317626953, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2351
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      6   2   18  4294867362           0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=45
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      10  8   0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1186
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=800
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      800       6   4   11  4294966297           0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=237
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=32
    num_vectors=1 total_exceptions=32
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        10  10  0   0                    32     0:-7.9999998744539955e+18, 1:7.9999998744539955e+18, 2:3.2175613495004365e+18, 3:-1.428295291294974e+18, 4:74196599420485632, ...

Column 'double_alp_4096' (DOUBLE)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=23978
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=6144
    num_vectors=2 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      4096      14  12  11  18446744073709550616 10     1024:nan, 1500:nan, 2000:inf, 2001:-inf, 2002:-0, ...
    1      2048      14  12  11  18446744073709550616 1536   0:-5.6894026020883821, 2:-5.7471123414096521, 4:5.2631058917995048, 6:3.0632557599260757, 8:7.4240896660071236, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2355
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      16  12  18  18446744073709451682 0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=49
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=1024
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      1024      16  14  0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1190
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=800
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      800       14  12  11  18446744073709550617 0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=305
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=12 (vector_size=4096) num_elements=32
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        0   0   64  10446744073709551616 0     

Column 'float_alp_32' (FLOAT)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=18848
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=6144
    num_vectors=192 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        6   4   11  4294966383           0     
    1      32        6   4   11  4294966316           0     
    2      32        6   4   11  4294966309           0     
    3      32        6   4   11  4294966310           0     
    4      32        6   4   11  4294966336           0     
    5      32        6   4   11  4294966502           0     
    6      32        6   4   11  4294966391           0     
    7      32        6   4   11  4294966485           0     
    8      32        6   4   11  4294966297           0     
    9      32        6   4   11  4294966418           0     
    10     32        6   4   11  4294966439           0     
    11     32        6   4   11  4294966297           0     
    12     32        6   4   11  4294966448           0     
    13     32        6   4   11  4294966312           0     
    14     32        6   4   11  4294966313           0     
    15     32        6   4   11  4294966450           0     
    16     32        6   4   11  4294966315           0     
    17     32        6   4   11  4294966300           0     
    18     32        6   4   11  4294966412           0     
    19     32        6   4   11  4294966389           0     
    20     32        6   4   11  4294966318           0     
    21     32        6   4   11  4294966307           0     
    22     32        6   4   11  4294966410           0     
    23     32        6   4   11  4294966332           0     
    24     32        6   4   11  4294966404           0     
    25     32        6   4   11  4294966324           0     
    26     32        6   4   11  4294966334           0     
    27     32        6   4   11  4294966353           0     
    28     32        6   4   11  4294966342           0     
    29     32        6   4   11  4294966336           0     
    30     32        6   4   11  4294966305           0     
    31     32        6   4   11  4294966296           0     
    32     32        6   4   11  4294966370           1      0:nan
    33     32        6   4   11  4294966376           0     
    34     32        6   4   11  4294966338           0     
    35     32        6   4   11  4294966342           0     
    36     32        6   4   11  4294966303           0     
    37     32        6   4   11  4294966320           0     
    38     32        6   4   11  4294966329           0     
    39     32        6   4   11  4294966299           0     
    40     32        6   4   11  4294966296           0     
    41     32        6   4   11  4294966305           0     
    42     32        6   4   11  4294966300           0     
    43     32        6   4   11  4294966384           0     
    44     32        6   4   11  4294966452           0     
    45     32        6   4   11  4294966310           0     
    46     32        6   4   11  4294966306           1      28:nan
    47     32        6   4   11  4294966346           0     
    48     32        6   4   11  4294966370           0     
    49     32        6   4   11  4294966320           0     
    50     32        6   4   11  4294966313           0     
    51     32        6   4   11  4294966350           0     
    52     32        6   4   11  4294966302           0     
    53     32        6   4   11  4294966377           0     
    54     32        6   4   11  4294966299           0     
    55     32        6   4   11  4294966322           0     
    56     32        6   4   11  4294966306           0     
    57     32        6   4   11  4294966356           0     
    58     32        6   4   11  4294966307           0     
    59     32        6   4   11  4294966342           0     
    60     32        6   4   11  4294966334           0     
    61     32        6   4   11  4294966311           0     
    62     32        6   4   11  4294966298           4      16:inf, 17:-inf, 18:-0, 19:1.4012984643248171e-45
    63     32        6   4   11  4294966306           1      31:nan
    64     32        6   4   11  4294966349           0     
    65     32        6   4   11  4294966298           0     
    66     32        6   4   11  4294966332           0     
    67     32        6   4   11  4294966302           0     
    68     32        6   4   11  4294966312           0     
    69     32        6   4   11  4294966332           0     
    70     32        6   4   11  4294966317           0     
    71     32        6   4   11  4294966316           0     
    72     32        6   4   11  4294966379           0     
    73     32        6   4   11  4294966501           0     
    74     32        6   4   11  4294966306           0     
    75     32        6   4   11  4294966297           0     
    76     32        6   4   11  4294966304           0     
    77     32        6   4   11  4294966302           0     
    78     32        6   4   11  4294966330           1      4:3.1415927410125732
    79     32        6   4   11  4294966447           0     
    80     32        6   4   11  4294966297           0     
    81     32        6   4   11  4294966309           0     
    82     32        6   4   11  4294966428           0     
    83     32        6   4   11  4294966414           0     
    84     32        6   4   11  4294966424           0     
    85     32        6   4   11  4294966381           0     
    86     32        6   4   11  4294966314           0     
    87     32        6   4   11  4294966397           0     
    88     32        6   4   11  4294966307           0     
    89     32        6   4   11  4294966316           0     
    90     32        6   4   11  4294966297           0     
    91     32        6   4   11  4294966305           0     
    92     32        6   4   11  4294966345           0     
    93     32        6   4   11  4294966558           0     
    94     32        6   4   11  4294966331           0     
    95     32        6   4   11  4294966353           0     
    96     32        6   4   11  4294966350           1      28:44974936064
    97     32        6   4   11  4294966409           0     
    98     32        6   4   11  4294966307           0     
    99     32        6   4   11  4294966390           0     
    100    32        6   4   11  4294966338           0     
    101    32        6   4   11  4294966378           0     
    102    32        6   4   11  4294966387           0     
    103    32        6   4   11  4294966360           0     
    104    32        6   4   11  4294966312           0     
    105    32        6   4   11  4294966338           0     
    106    32        6   4   11  4294966433           0     
    107    32        6   4   11  4294966414           0     
    108    32        6   4   11  4294966334           0     
    109    32        6   4   11  4294966498           0     
    110    32        6   4   11  4294966314           0     
    111    32        6   4   11  4294966407           0     
    112    32        6   4   11  4294966427           0     
    113    32        6   4   11  4294966333           0     
    114    32        6   4   11  4294966314           0     
    115    32        6   4   11  4294966345           1      31:-1243432448
    116    32        6   4   11  4294966483           0     
    117    32        6   4   11  4294966458           0     
    118    32        6   4   11  4294966316           0     
    119    32        6   4   11  4294966323           0     
    120    32        6   4   11  4294966317           0     
    121    32        6   4   11  4294966327           0     
    122    32        6   4   11  4294966303           0     
    123    32        6   4   11  4294966335           0     
    124    32        6   4   11  4294966555           0     
    125    32        6   4   11  4294966426           0     
    126    32        6   4   11  4294966336           0     
    127    32        6   4   11  4294966296           0     
    128    32        6   4   11  4294966437           16     0:-5.6894025802612305, 2:-5.7471122741699219, 4:5.2631058692932129, 6:3.063255786895752, 8:7.4240894317626953, ...
    129    32        6   4   11  4294966560           16     0:8.3615312576293945, 2:-7.4509210586547852, 4:-4.1556353569030762, 6:6.5207810401916504, 8:6.0981354713439941, ...
    130    32        6   4   11  4294966563           16     0:-4.0016179084777832, 2:1.9761660099029541, 4:8.0578994750976562, 6:7.5452351570129395, 8:1.8644313812255859, ...
    131    32        6   4   11  4294966474           16     0:-8.7062625885009766, 2:1.435447096824646, 4:3.8890092372894287, 6:-3.6610684394836426, 8:-0.71133530139923096, ...
    132    32        6   4   11  4294966388           16     0:-4.6208209991455078, 2:-8.5813560485839844, 4:-9.9415788650512695, 6:-0.55013293027877808, 8:8.1476030349731445, ...
    133    32        6   4   11  4294966677           16     0:0.25335460901260376, 2:-9.1122446060180664, 4:-2.0596992969512939, 6:-4.3087539672851562, 8:-7.7232322692871094, ...
    134    32        6   4   11  4294966715           16     0:4.4278688430786133, 2:2.7280275821685791, 4:-4.8478555679321289, 6:-9.1888256072998047, 8:3.7317984104156494, ...
    135    32        6   4   11  4294966368           16     0:-7.6852478981018066, 2:7.4739718437194824, 4:2.7575418949127197, 6:8.0490665435791016, 8:6.5803546905517578, ...
    136    32        6   4   11  4294966974           16     0:7.2348499298095703, 2:-1.0716096162796021, 4:-2.3152074813842773, 6:7.1512470245361328, 8:5.1870203018188477, ...
    137    32        6   4   11  4294966370           16     0:-1.8074220418930054, 2:-7.9748015403747559, 4:2.1155848503112793, 6:6.8344674110412598, 8:1.1937688589096069, ...
    138    32        6   4   11  4294966363           16     0:9.1183767318725586, 2:7.768073558807373, 4:9.8971595764160156, 6:-8.2359657287597656, 8:9.2227096557617188, ...
    139    32        6   4   11  4294966359           16     0:0.89655309915542603, 2:1.6093521118164062, 4:9.9942760467529297, 6:2.524686336517334, 8:-5.8538198471069336, ...
    140    32        6   4   11  4294966690           16     0:4.9172005653381348, 2:-7.5035834312438965, 4:3.6151180267333984, 6:7.541811466217041, 8:9.3921546936035156, ...
    141    32        6   4   11  4294966411           16     0:2.042339563369751, 2:6.1317868232727051, 4:-5.9905099868774414, 6:-8.8105688095092773, 8:-1.2170037031173706, ...
    142    32        6   4   11  4294966296           16     0:-4.4248027801513672, 2:0.57156217098236084, 4:-9.8227348327636719, 6:-5.9869794845581055, 8:6.5693860054016113, ...
    143    32        6   4   11  4294966340           16     0:-3.0235893726348877, 2:2.6417965888977051, 4:8.9537601470947266, 6:-7.9811758995056152, 8:-4.0086865425109863, ...
    144    32        6   4   11  4294966455           16     0:9.5796222686767578, 2:-5.7074384689331055, 4:2.9563488960266113, 6:-6.2431430816650391, 8:0.061678990721702576, ...
    145    32        6   4   11  4294966472           16     0:2.5911538600921631, 2:-4.569058895111084, 4:-3.6482639312744141, 6:-6.2192096710205078, 8:-9.0629615783691406, ...
    146    32        6   4   11  4294966470           16     0:-2.453639030456543, 2:3.5028011798858643, 4:3.7403855323791504, 6:1.2925810813903809, 8:6.8849740028381348, ...
    147    32        6   4   11  4294966505           16     0:-0.48064544796943665, 2:-5.8223457336425781, 4:5.4156122207641602, 6:-8.9528999328613281, 8:-6.2795400619506836, ...
    148    32        6   4   11  4294966312           16     0:-8.2931728363037109, 2:-2.6442804336547852, 4:6.4661884307861328, 6:0.31723803281784058, 8:-8.0026636123657227, ...
    149    32        6   4   11  4294966328           16     0:5.4584298133850098, 2:-7.3696346282958984, 4:-7.4889955520629883, 6:-8.4723014831542969, 8:6.1431107521057129, ...
    150    32        6   4   11  4294966528           16     0:-0.84008479118347168, 2:-6.9534440040588379, 4:-8.6861028671264648, 6:8.7475690841674805, 8:-0.31845855712890625, ...
    151    32        6   4   11  4294966300           16     0:-7.0607457160949707, 2:0.5453035831451416, 4:-2.2366857528686523, 6:2.8563783168792725, 8:-3.0961558818817139, ...
    152    32        6   4   11  4294966505           16     0:-4.5059237480163574, 2:5.2170867919921875, 4:0.93154287338256836, 6:-0.82804101705551147, 8:-6.6850042343139648, ...
    153    32        6   4   11  4294966381           16     0:-6.4780902862548828, 2:2.4468653202056885, 4:-6.1978468894958496, 6:4.6424522399902344, 8:8.8740320205688477, ...
    154    32        6   4   11  4294966424           16     0:8.5238809585571289, 2:6.095062255859375, 4:-5.5584826469421387, 6:-6.442237377166748, 8:4.5772285461425781, ...
    155    32        6   4   11  4294966569           16     0:2.440791130065918, 2:-4.9799723625183105, 4:1.4768251180648804, 6:3.1326212882995605, 8:8.0447282791137695, ...
    156    32        6   4   11  4294966335           16     0:-1.3979425430297852, 2:8.9291305541992188, 4:-1.981164813041687, 6:5.6073098182678223, 8:7.7777485847473145, ...
    157    32        6   4   11  4294966574           16     0:0.31318798661231995, 2:0.78189116716384888, 4:-4.1994161605834961, 6:-9.2485780715942383, 8:0.93401038646697998, ...
    158    32        6   4   11  4294966305           16     0:-3.9413819313049316, 2:6.36053466796875, 4:6.3355894088745117, 6:-7.4928703308105469, 8:8.0388040542602539, ...
    159    32        6   4   11  4294966404           16     0:4.2884831428527832, 2:1.201833963394165, 4:0.27708917856216431, 6:-6.5582156181335449, 8:-1.0237270593643188, ...
    160    32        6   4   0   0                    32     0:0.98619550466537476, 1:-3.7603194713592529, 2:-0.34999150037765503, 3:0.1334528774023056, 4:-2.2552545070648193, ...
    161    32        6   4   0   0                    32     0:0.030309226363897324, 1:-8.5821685791015625, 2:-3.74273681640625, 3:8.7059421539306641, 4:7.0136051177978516, ...
    162    32        6   4   0   0                    32     0:2.0220539569854736, 1:9.8072357177734375, 2:-3.4949219226837158, 3:8.8254489898681641, 4:8.2946224212646484, ...
    163    32        6   4   0   0                    32     0:1.0675803422927856, 1:2.8326382637023926, 2:4.0758461952209473, 3:-2.5348036289215088, 4:1.2731994390487671, ...
    164    32        6   4   0   0                    32     0:3.2998902797698975, 1:-0.039192099124193192, 2:4.8564996719360352, 3:-3.4591071605682373, 4:7.801140308380127, ...
    165    32        6   4   0   0                    32     0:-3.3393025398254395, 1:7.6992859840393066, 2:-2.334315299987793, 3:-0.12998028099536896, 4:-4.3339047431945801, ...
    166    32        6   4   0   0                    32     0:1.9769080877304077, 1:-5.9780254364013672, 2:1.8046531677246094, 3:-1.847342848777771, 4:-0.60948920249938965, ...
    167    32        6   4   0   0                    32     0:5.7271547317504883, 1:2.6443319320678711, 2:-2.5295965671539307, 3:-4.5700249671936035, 4:-5.3643283843994141, ...
    168    32        6   4   0   0                    32     0:4.6482772827148438, 1:7.6332497596740723, 2:-7.5700922012329102, 3:2.6927852630615234, 4:1.642876148223877, ...
    169    32        6   4   0   0                    32     0:0.24569518864154816, 1:-7.7142844200134277, 2:5.2960195541381836, 3:3.5779545307159424, 4:5.4597344398498535, ...
    170    32        6   4   0   0                    32     0:-4.3823604583740234, 1:-5.8408727645874023, 2:-9.1602916717529297, 3:-0.41479822993278503, 4:-6.3655343055725098, ...
    171    32        6   4   0   0                    32     0:-9.0268468856811523, 1:1.6203017234802246, 2:-1.4785804748535156, 3:0.9606471061706543, 4:0.42146375775337219, ...
    172    32        6   4   0   0                    32     0:4.4868879318237305, 1:4.9150676727294922, 2:1.1585489511489868, 3:1.693361759185791, 4:-7.3269882202148438, ...
    173    32        6   4   0   0                    32     0:-1.6951805353164673, 1:7.769282341003418, 2:6.4865379333496094, 3:2.6007976531982422, 4:7.1624078750610352, ...
    174    32        6   4   0   0                    32     0:-8.3955554962158203, 1:-3.7560725212097168, 2:-9.6851415634155273, 3:-9.6570043563842773, 4:8.3320655822753906, ...
    175    32        6   4   0   0                    32     0:0.080075323581695557, 1:8.984013557434082, 2:6.6566381454467773, 3:-2.7513735294342041, 4:7.2728285789489746, ...
    176    32        6   4   0   0                    32     0:1.6899958848953247, 1:6.6758389472961426, 2:2.8515520095825195, 3:-8.4288434982299805, 4:4.8112945556640625, ...
    177    32        6   4   0   0                    32     0:-2.080768346786499, 1:3.3861720561981201, 2:7.8378620147705078, 3:-3.8789706230163574, 4:1.0375427007675171, ...
    178    32        6   4   0   0                    32     0:9.7345819473266602, 1:-4.5726804733276367, 2:-8.0283412933349609, 3:6.5862846374511719, 4:4.1335105895996094, ...
    179    32        6   4   0   0                    32     0:0.4552028477191925, 1:-0.58265292644500732, 2:3.1211004257202148, 3:1.1915770769119263, 4:3.7407829761505127, ...
    180    32        6   4   0   0                    32     0:1.5322799682617188, 1:1.1753189563751221, 2:-2.5766096115112305, 3:5.7128620147705078, 4:-4.9440312385559082, ...
    181    32        6   4   0   0                    32     0:5.7162528038024902, 1:1.7989577054977417, 2:-9.8712959289550781, 3:5.4503259658813477, 4:4.049767017364502, ...
    182    32        6   4   0   0                    32     0:5.467620849609375, 1:8.2993173599243164, 2:-6.2172179222106934, 3:8.4473495483398438, 4:3.9124929904937744, ...
    183    32        6   4   0   0                    32     0:1.9925512075424194, 1:0.12660616636276245, 2:-2.9917349815368652, 3:8.2586202621459961, 4:-3.2045953273773193, ...
    184    32        6   4   0   0                    32     0:8.0953264236450195, 1:2.9503293037414551, 2:-4.5391874313354492, 3:-6.4561500549316406, 4:-4.1146655082702637, ...
    185    32        6   4   0   0                    32     0:1.6721007823944092, 1:-2.1975953578948975, 2:-2.8973672389984131, 3:-9.0950164794921875, 4:-5.6418256759643555, ...
    186    32        6   4   0   0                    32     0:1.2251135110855103, 1:-5.0751166343688965, 2:-1.5290416479110718, 3:5.8714132308959961, 4:-9.3644304275512695, ...
    187    32        6   4   0   0                    32     0:5.2376723289489746, 1:5.6301131248474121, 2:-4.4848518371582031, 3:-5.915064811706543, 4:-9.6648740768432617, ...
    188    32        6   4   0   0                    32     0:-1.1176950931549072, 1:5.0005683898925781, 2:0.633220374584198, 3:0.75565874576568604, 4:-4.4380097389221191, ...
    189    32        6   4   0   0                    32     0:3.1610996723175049, 1:-9.8388175964355469, 2:8.8634967803955078, 3:-5.257110595703125, 4:-7.8477163314819336, ...
    190    32        6   4   0   0                    32     0:-1.3803218603134155, 1:-3.9101493358612061, 2:-6.0380897521972656, 3:-8.6861581802368164, 4:7.7423863410949707, ...
    191    32        6   4   0   0                    32     0:-9.8062620162963867, 1:7.1591019630432129, 2:4.6231470108032227, 3:8.9351205825805664, 4:5.6323094367980957, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2754
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=1024
    num_vectors=32 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        6   2   18  4294871265           0     
    1      32        6   2   18  4294867583           0     
    2      32        6   2   18  4294867616           0     
    3      32        6   2   18  4294882325           0     
    4      32        6   2   18  4294872839           0     
    5      32        6   2   18  4294873934           0     
    6      32        6   2   18  4294877022           0     
    7      32        6   2   18  4294871338           0     
    8      32        6   2   18  4294869331           0     
    9      32        6   2   18  4294868762           0     
    10     32        6   2   18  4294878646           0     
    11     32        6   2   18  4294867686           0     
    12     32        6   2   18  4294874507           0     
    13     32        6   2   18  4294868480           0     
    14     32        6   2   18  4294868220           0     
    15     32        6   2   18  4294873766           0     
    16     32        6   2   18  4294874531           0     
    17     32        6   2   18  4294877239           0     
    18     32        6   2   18  4294873026           0     
    19     32        6   2   18  4294868369           0     
    20     32        6   2   18  4294868197           0     
    21     32        6   2   18  4294867811           0     
    22     32        6   2   18  4294867362           0     
    23     32        6   2   18  4294868027           0     
    24     32        6   2   18  4294868758           0     
    25     32        6   2   18  4294867759           0     
    26     32        6   2   18  4294876098           0     
    27     32        6   2   18  4294871071           0     
    28     32        6   2   18  4294875247           0     
    29     32        6   2   18  4294867511           0     
    30     32        6   2   18  4294883872           0     
    31     32        6   2   18  4294868597           0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=450
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=1024
    num_vectors=32 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        10  8   0   777                  0     
    1      32        10  8   0   777                  0     
    2      32        10  8   0   777                  0     
    3      32        10  8   0   777                  0     
    4      32        10  8   0   777                  0     
    5      32        10  8   0   777                  0     
    6      32        10  8   0   777                  0     
    7      32        10  8   0   777                  0     
    8      32        10  8   0   777                  0     
    9      32        10  8   0   777                  0     
    10     32        10  8   0   777                  0     
    11     32        10  8   0   777                  0     
    12     32        10  8   0   777                  0     
    13     32        10  8   0   777                  0     
    14     32        10  8   0   777                  0     
    15     32        10  8   0   777                  0     
    16     32        10  8   0   777                  0     
    17     32        10  8   0   777                  0     
    18     32        10  8   0   777                  0     
    19     32        10  8   0   777                  0     
    20     32        10  8   0   777                  0     
    21     32        10  8   0   777                  0     
    22     32        10  8   0   777                  0     
    23     32        10  8   0   777                  0     
    24     32        10  8   0   777                  0     
    25     32        10  8   0   777                  0     
    26     32        10  8   0   777                  0     
    27     32        10  8   0   777                  0     
    28     32        10  8   0   777                  0     
    29     32        10  8   0   777                  0     
    30     32        10  8   0   777                  0     
    31     32        10  8   0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1498
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=800
    num_vectors=25 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        6   4   11  4294966356           0     
    1      32        6   4   11  4294966297           0     
    2      32        6   4   11  4294966322           0     
    3      32        6   4   11  4294966327           0     
    4      32        6   4   11  4294966308           0     
    5      32        6   4   11  4294966336           0     
    6      32        6   4   11  4294966368           0     
    7      32        6   4   11  4294966387           0     
    8      32        6   4   11  4294966439           0     
    9      32        6   4   11  4294966363           0     
    10     32        6   4   11  4294966373           0     
    11     32        6   4   11  4294966379           0     
    12     32        6   4   11  4294966388           0     
    13     32        6   4   11  4294966314           0     
    14     32        6   4   11  4294966507           0     
    15     32        6   4   11  4294966352           0     
    16     32        6   4   11  4294966320           0     
    17     32        6   4   11  4294966383           0     
    18     32        6   4   11  4294966300           0     
    19     32        6   4   11  4294966311           0     
    20     32        6   4   11  4294966306           0     
    21     32        6   4   11  4294966363           0     
    22     32        6   4   11  4294966366           0     
    23     32        6   4   11  4294966299           0     
    24     32        6   4   11  4294966400           0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=237
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=32
    num_vectors=1 total_exceptions=32
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        10  10  0   0                    32     0:-7.9999998744539955e+18, 1:7.9999998744539955e+18, 2:3.2175613495004365e+18, 3:-1.428295291294974e+18, 4:74196599420485632, ...

Column 'double_alp_32' (DOUBLE)
  Row group 0: rows=6144 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=25800
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=6144
    num_vectors=192 total_exceptions=1546
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        14  12  11  18446744073709550703 0     
    1      32        14  12  11  18446744073709550636 0     
    2      32        14  12  11  18446744073709550629 0     
    3      32        14  12  11  18446744073709550630 0     
    4      32        14  12  11  18446744073709550656 0     
    5      32        14  12  11  18446744073709550822 0     
    6      32        14  12  11  18446744073709550711 0     
    7      32        14  12  11  18446744073709550805 0     
    8      32        14  12  11  18446744073709550617 0     
    9      32        14  12  11  18446744073709550738 0     
    10     32        14  12  11  18446744073709550759 0     
    11     32        14  12  11  18446744073709550617 0     
    12     32        14  12  11  18446744073709550768 0     
    13     32        14  12  11  18446744073709550632 0     
    14     32        14  12  11  18446744073709550633 0     
    15     32        14  12  11  18446744073709550770 0     
    16     32        14  12  11  18446744073709550635 0     
    17     32        14  12  11  18446744073709550620 0     
    18     32        14  12  11  18446744073709550732 0     
    19     32        14  12  11  18446744073709550709 0     
    20     32        14  12  11  18446744073709550638 0     
    21     32        14  12  11  18446744073709550627 0     
    22     32        14  12  11  18446744073709550730 0     
    23     32        14  12  11  18446744073709550652 0     
    24     32        14  12  11  18446744073709550724 0     
    25     32        14  12  11  18446744073709550644 0     
    26     32        14  12  11  18446744073709550654 0     
    27     32        14  12  11  18446744073709550673 0     
    28     32        14  12  11  18446744073709550662 0     
    29     32        14  12  11  18446744073709550656 0     
    30     32        14  12  11  18446744073709550625 0     
    31     32        14  12  11  18446744073709550616 0     
    32     32        14  12  11  18446744073709550690 1      0:nan
    33     32        14  12  11  18446744073709550696 0     
    34     32        14  12  11  18446744073709550658 0     
    35     32        14  12  11  18446744073709550662 0     
    36     32        14  12  11  18446744073709550623 0     
    37     32        14  12  11  18446744073709550640 0     
    38     32        14  12  11  18446744073709550649 0     
    39     32        14  12  11  18446744073709550619 0     
    40     32        14  12  11  18446744073709550616 0     
    41     32        14  12  11  18446744073709550625 0     
    42     32        14  12  11  18446744073709550620 0     
    43     32        14  12  11  18446744073709550704 0     
    44     32        14  12  11  18446744073709550772 0     
    45     32        14  12  11  18446744073709550630 0     
    46     32        14  12  11  18446744073709550626 1      28:nan
    47     32        14  12  11  18446744073709550666 0     
    48     32        14  12  11  18446744073709550690 0     
    49     32        14  12  11  18446744073709550640 0     
    50     32        14  12  11  18446744073709550633 0     
    51     32        14  12  11  18446744073709550670 0     
    52     32        14  12  11  18446744073709550622 0     
    53     32        14  12  11  18446744073709550697 0     
    54     32        14  12  11  18446744073709550619 0     
    55     32        14  12  11  18446744073709550642 0     
    56     32        14  12  11  18446744073709550626 0     
    57     32        14  12  11  18446744073709550676 0     
    58     32        14  12  11  18446744073709550627 0     
    59     32        14  12  11  18446744073709550662 0     
    60     32        14  12  11  18446744073709550654 0     
    61     32        14  12  11  18446744073709550631 0     
    62     32        14  12  11  18446744073709550618 4      16:inf, 17:-inf, 18:-0, 19:4.9406564584124654e-324
    63     32        14  12  11  18446744073709550626 1      31:nan
    64     32        14  12  11  18446744073709550669 0     
    65     32        14  12  11  18446744073709550618 0     
    66     32        14  12  11  18446744073709550652 0     
    67     32        14  12  11  18446744073709550622 0     
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    129    32        14  12  11  18446744073709550880 16     0:8.3615310165433918, 2:-7.4509208403525999, 4:-4.1556354486025482, 6:6.5207809345366901, 8:6.0981354522486946, ...
    130    32        14  12  11  18446744073709550883 16     0:-4.0016177565494946, 2:1.9761659612096527, 4:8.0578997873910296, 6:7.5452351656382159, 8:1.8644314134978135, ...
    131    32        14  12  11  18446744073709550794 16     0:-8.7062622521571491, 2:1.4354470416709053, 4:3.8890091633305257, 6:-3.6610683282734504, 8:-0.71133532824648515, ...
    132    32        14  12  11  18446744073709550708 16     0:-4.6208211430056672, 2:-8.5813557849872311, 4:-9.941579321146051, 6:-0.55013293847550604, 8:8.1476033946762261, ...
    133    32        14  12  11  18446744073709550997 16     0:0.2533545960602801, 2:-9.1122445962695, 4:-2.0596992584046814, 6:-4.3087539817807592, 8:-7.7232320987702971, ...
    134    32        14  12  11  18446744073709551035 16     0:4.4278690443430024, 2:2.7280275284446809, 4:-4.8478556577229304, 6:-9.1888252642959145, 8:3.7317983148228273, ...
    135    32        14  12  11  18446744073709550688 16     0:-7.6852479162007246, 2:7.4739719701666463, 4:2.7575418619624026, 6:8.0490660748490193, 8:6.5803545809650981, ...
    136    32        14  12  11  18446744073709551294 16     0:7.2348498055074062, 2:-1.0716095772092904, 4:-2.315207571730109, 6:7.1512467947328613, 8:5.1870204923517775, ...
    137    32        14  12  11  18446744073709550690 16     0:-1.8074220521761097, 2:-7.974801732640632, 4:2.1155849324871756, 6:6.834467273971967, 8:1.1937688569912508, ...
    138    32        14  12  11  18446744073709550683 16     0:9.118376566890614, 2:7.7680734846461874, 4:9.8971594199675277, 6:-8.2359658322110167, 8:9.2227097535826132, ...
    139    32        14  12  11  18446744073709550679 16     0:0.89655311572229834, 2:1.6093520595004884, 4:9.9942761479839533, 6:2.5246863726085111, 8:-5.8538199798720996, ...
    140    32        14  12  11  18446744073709551010 16     0:4.91720075314237, 2:-7.5035836009805905, 4:3.6151179289175683, 6:7.5418116779382434, 8:9.3921545424686848, ...
    141    32        14  12  11  18446744073709550731 16     0:2.0423396622180889, 2:6.1317867346737938, 4:-5.9905097657978379, 6:-8.8105687167995406, 8:-1.2170036882014579, ...
    142    32        14  12  11  18446744073709550616 16     0:-4.4248025522874324, 2:0.57156218779601531, 4:-9.8227343764463715, 6:-5.9869796689701227, 8:6.5693860547367873, ...
    143    32        14  12  11  18446744073709550660 16     0:-3.0235893916984216, 2:2.6417965307412583, 4:8.9537604738820384, 6:-7.9811759900529164, 8:-4.0086864686154566, ...
    144    32        14  12  11  18446744073709550775 16     0:9.5796223926324124, 2:-5.7074385015131295, 4:2.9563489203160698, 6:-6.2431429413942592, 8:0.061678992210847383, ...
    145    32        14  12  11  18446744073709550792 16     0:2.5911538387824695, 2:-4.5690591258260795, 4:-3.6482640430217295, 6:-6.2192095071071076, 8:-9.0629618159354823, ...
    146    32        14  12  11  18446744073709550790 16     0:-2.4536389886526688, 2:3.5028012979965584, 4:3.7403854407184878, 6:1.2925810948657523, 8:6.8849740579384928, ...
    147    32        14  12  11  18446744073709550825 16     0:-0.48064543664115833, 2:-5.8223455347540902, 4:5.4156123212012801, 6:-8.952899598503107, 8:-6.2795400024970638, ...
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    150    32        14  12  11  18446744073709550848 16     0:-0.84008481683608083, 2:-6.9534442089590929, 4:-8.6861029132294689, 6:8.7475688579875754, 8:-0.3184585478003521, ...
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    152    32        14  12  11  18446744073709550825 16     0:-4.5059238112489295, 2:5.217086960594008, 4:0.93154285823395355, 6:-0.82804099455095814, 8:-6.6850043946836397, ...
    153    32        14  12  11  18446744073709550701 16     0:-6.4780904790686398, 2:2.4468653891885506, 4:-6.1978471138785123, 6:4.6424521356476234, 8:8.8740317586578481, ...
    154    32        14  12  11  18446744073709550744 16     0:8.52388143249315, 2:6.0950624860295877, 4:-5.5584825992302189, 6:-6.4422376112934669, 8:4.5772287599494854, ...
    155    32        14  12  11  18446744073709550889 16     0:2.4407912062346981, 2:-4.9799722992235687, 4:1.4768251244168451, 6:3.1326213638093514, 8:8.0447280418146345, ...
    156    32        14  12  11  18446744073709550655 16     0:-1.3979425730507333, 2:8.9291301691148313, 4:-1.9811647902589369, 6:5.6073099550004502, 8:7.7777484966271349, ...
    157    32        14  12  11  18446744073709550894 16     0:0.31318799197485259, 2:0.78189115255742125, 4:-4.1994161005948092, 6:-9.2485782274463677, 8:0.93401039078769621, ...
    158    32        14  12  11  18446744073709550625 16     0:-3.9413819387106641, 2:6.3605348967262305, 4:6.3355894119144125, 6:-7.4928704268223889, 8:8.0388039086804, ...
    159    32        14  12  11  18446744073709550724 16     0:4.2884833767645052, 2:1.2018339557526869, 4:0.27708918219772949, 6:-6.5582153829331951, 8:-1.0237270643332752, ...
    160    32        14  12  0   0                    32     0:0.98619550441899628, 1:-3.7603195733564965, 2:-0.34999150139969903, 3:0.13345287723017574, 4:-2.2552545378626987, ...
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    164    32        14  12  0   0                    32     0:3.2998903374048272, 1:-0.039192097718393493, 2:4.8564995546281331, 3:-3.4591070495844689, 4:7.8011404866940603, ...
    165    32        14  12  0   0                    32     0:-3.3393025819608448, 1:7.6992861267109021, 2:-2.3343151863427347, 3:-0.12998027809437485, 4:-4.3339046885598895, ...
    166    32        14  12  0   0                    32     0:1.9769081168059244, 1:-5.9780254400246156, 2:1.8046532073106891, 3:-1.8473428184975349, 4:-0.60948918547399256, ...
    167    32        14  12  0   0                    32     0:5.7271546356045411, 1:2.6443319643230301, 2:-2.5295964611953825, 3:-4.5700249378307065, 4:-5.3643282505631404, ...
    168    32        14  12  0   0                    32     0:4.6482773086323785, 1:7.6332496986298608, 2:-7.5700921134951669, 3:2.6927851808921965, 4:1.6428762027311383, ...
    169    32        14  12  0   0                    32     0:0.24569519186426803, 1:-7.7142846015922162, 2:5.296019433959664, 3:3.5779544845953337, 4:5.459734467809632, ...
    170    32        14  12  0   0                    32     0:-4.3823605780407142, 1:-5.8408728185879406, 2:-9.1602915196354804, 3:-0.4147982323665611, 4:-6.3655341491596547, ...
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    175    32        14  12  0   0                    32     0:0.080075327275126451, 1:8.9840139404560819, 2:6.6566380693333427, 3:-2.75137352442934, 4:7.2728284712765916, ...
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    179    32        14  12  0   0                    32     0:0.45520285235329805, 1:-0.58265292789138612, 2:3.1211004068220105, 3:1.1915770708237261, 4:3.7407829122765968, ...
    180    32        14  12  0   0                    32     0:1.5322800256643609, 1:1.1753189143255649, 2:-2.5766095632162855, 3:5.7128620387194733, 4:-4.9440310924567834, ...
    181    32        14  12  0   0                    32     0:5.7162528403017054, 1:1.7989576463980339, 2:-9.871295818742043, 3:5.4503257361534025, 4:4.0497669426751131, ...
    182    32        14  12  0   0                    32     0:5.4676209982698705, 1:8.2993173231910582, 2:-6.2172180059909845, 3:8.4473497899298078, 4:3.9124930425244209, ...
    183    32        14  12  0   0                    32     0:1.9925512603817586, 1:0.12660616955186832, 2:-2.9917349399110904, 3:8.2586201293275927, 4:-3.2045952822937815, ...
    184    32        14  12  0   0                    32     0:8.0953267620034204, 1:2.9503292765057521, 2:-4.5391876634495887, 3:-6.4561500280262383, 4:-4.1146652777476245, ...
    185    32        14  12  0   0                    32     0:1.6721008306574325, 1:-2.1975952707390158, 2:-2.8973671535649537, 3:-9.0950162201076132, 4:-5.6418258913608375, ...
    186    32        14  12  0   0                    32     0:1.2251135674135649, 1:-5.0751167678352642, 2:-1.5290416971839027, 3:5.8714131917039269, 4:-9.3644304282047273, ...
    187    32        14  12  0   0                    32     0:5.2376723141578196, 1:5.6301129440991726, 2:-4.4848518145311438, 3:-5.9150648522037743, 4:-9.6648737977605546, ...
    188    32        14  12  0   0                    32     0:-1.1176951131509882, 1:5.0005681968987803, 2:0.63322039979124778, 3:0.75565874425611801, 4:-4.4380096874285506, ...
    189    32        14  12  0   0                    32     0:3.1610996562355953, 1:-9.8388178747476562, 2:8.86349644297872, 3:-5.2571106103962943, 4:-7.8477163080531094, ...
    190    32        14  12  0   0                    32     0:-1.3803218971563247, 1:-3.9101493632402851, 2:-6.038089650969348, 3:-8.6861577202510869, 4:7.7423864445777308, ...
    191    32        14  12  0   0                    32     0:-9.806262317234884, 1:7.1591018251743872, 2:4.6231469233923228, 3:8.9351207743550294, 4:5.6323095784117587, ...
  Row group 1: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=2882
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=1024
    num_vectors=32 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        16  12  18  18446744073709455585 0     
    1      32        16  12  18  18446744073709451903 0     
    2      32        16  12  18  18446744073709451936 0     
    3      32        16  12  18  18446744073709466645 0     
    4      32        16  12  18  18446744073709457159 0     
    5      32        16  12  18  18446744073709458254 0     
    6      32        16  12  18  18446744073709461342 0     
    7      32        16  12  18  18446744073709455658 0     
    8      32        16  12  18  18446744073709453651 0     
    9      32        16  12  18  18446744073709453082 0     
    10     32        16  12  18  18446744073709462966 0     
    11     32        16  12  18  18446744073709452006 0     
    12     32        16  12  18  18446744073709458827 0     
    13     32        16  12  18  18446744073709452800 0     
    14     32        16  12  18  18446744073709452540 0     
    15     32        16  12  18  18446744073709458086 0     
    16     32        16  12  18  18446744073709458851 0     
    17     32        16  12  18  18446744073709461559 0     
    18     32        16  12  18  18446744073709457346 0     
    19     32        16  12  18  18446744073709452689 0     
    20     32        16  12  18  18446744073709452517 0     
    21     32        16  12  18  18446744073709452131 0     
    22     32        16  12  18  18446744073709451682 0     
    23     32        16  12  18  18446744073709452347 0     
    24     32        16  12  18  18446744073709453078 0     
    25     32        16  12  18  18446744073709452079 0     
    26     32        16  12  18  18446744073709460418 0     
    27     32        16  12  18  18446744073709455391 0     
    28     32        16  12  18  18446744073709459567 0     
    29     32        16  12  18  18446744073709451831 0     
    30     32        16  12  18  18446744073709468192 0     
    31     32        16  12  18  18446744073709452917 0     
  Row group 2: rows=1024 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=578
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=1024
    num_vectors=32 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        16  14  0   777                  0     
    1      32        16  14  0   777                  0     
    2      32        16  14  0   777                  0     
    3      32        16  14  0   777                  0     
    4      32        16  14  0   777                  0     
    5      32        16  14  0   777                  0     
    6      32        16  14  0   777                  0     
    7      32        16  14  0   777                  0     
    8      32        16  14  0   777                  0     
    9      32        16  14  0   777                  0     
    10     32        16  14  0   777                  0     
    11     32        16  14  0   777                  0     
    12     32        16  14  0   777                  0     
    13     32        16  14  0   777                  0     
    14     32        16  14  0   777                  0     
    15     32        16  14  0   777                  0     
    16     32        16  14  0   777                  0     
    17     32        16  14  0   777                  0     
    18     32        16  14  0   777                  0     
    19     32        16  14  0   777                  0     
    20     32        16  14  0   777                  0     
    21     32        16  14  0   777                  0     
    22     32        16  14  0   777                  0     
    23     32        16  14  0   777                  0     
    24     32        16  14  0   777                  0     
    25     32        16  14  0   777                  0     
    26     32        16  14  0   777                  0     
    27     32        16  14  0   777                  0     
    28     32        16  14  0   777                  0     
    29     32        16  14  0   777                  0     
    30     32        16  14  0   777                  0     
    31     32        16  14  0   777                  0     
  Row group 3: rows=808 encodings=[ RLE ALP ] compression=uncompressed null_count=8 compressed_bytes=1598
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=800
    num_vectors=25 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        14  12  11  18446744073709550676 0     
    1      32        14  12  11  18446744073709550617 0     
    2      32        14  12  11  18446744073709550642 0     
    3      32        14  12  11  18446744073709550647 0     
    4      32        14  12  11  18446744073709550628 0     
    5      32        14  12  11  18446744073709550656 0     
    6      32        14  12  11  18446744073709550688 0     
    7      32        14  12  11  18446744073709550707 0     
    8      32        14  12  11  18446744073709550759 0     
    9      32        14  12  11  18446744073709550683 0     
    10     32        14  12  11  18446744073709550693 0     
    11     32        14  12  11  18446744073709550699 0     
    12     32        14  12  11  18446744073709550708 0     
    13     32        14  12  11  18446744073709550634 0     
    14     32        14  12  11  18446744073709550827 0     
    15     32        14  12  11  18446744073709550672 0     
    16     32        14  12  11  18446744073709550640 0     
    17     32        14  12  11  18446744073709550703 0     
    18     32        14  12  11  18446744073709550620 0     
    19     32        14  12  11  18446744073709550631 0     
    20     32        14  12  11  18446744073709550626 0     
    21     32        14  12  11  18446744073709550683 0     
    22     32        14  12  11  18446744073709550686 0     
    23     32        14  12  11  18446744073709550619 0     
    24     32        14  12  11  18446744073709550720 0     
  Row group 4: rows=32 encodings=[ RLE ALP ] compression=uncompressed null_count=0 compressed_bytes=305
    ALP header: compression_mode=0 integer_encoding=0 log_vector_size=5 (vector_size=32) num_elements=32
    num_vectors=1 total_exceptions=0
    vector elems     exp fac bw  frame_of_ref         n_exc  first exceptions (pos:value)
    0      32        0   0   64  10446744073709551616 0     

Round-trip verification (bit-exact, including NaN/-0.0):
  float_plain      OK
  double_plain     OK
  float_alp_1024   OK
  double_alp_1024  OK
  float_alp_4096   OK
  double_alp_4096  OK
  float_alp_32     OK
  double_alp_32    OK

alamb
alamb commented Aug 4, 2026
View reviewed changes
Comment thread data/README.md Outdated
Comment thread data/README.md
The same values appear in `PLAIN`-encoded reference columns so decoders can
bit-compare the `ALP` columns against known results:

| Column | Encoding | Rationale / coverage |

@alamb alamb Aug 4, 2026

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I tried to explain both what is in the file, as well as to explain the rationale for including each piece

Comment thread data/alp_extended.zstd.parquet

@alamb alamb Aug 4, 2026

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You can verify this a bit with standard tools. For example, using the tools from the Rust implementation in apache/arrow-rs#9372

andrewlamb@Andrews-MacBook-Pro-3:~/Software/parquet-testing$ ~/Software/arrow-rs/target/release/parquet-schema data/alp_extended.zstd.parquet
Metadata for file: data/alp_extended.zstd.parquet

version: 2
num of rows: 9000
created by: parquet-cpp-arrow version 23.0.0-SNAPSHOT
message schema {
  OPTIONAL FLOAT float_plain;
  OPTIONAL DOUBLE double_plain;
  OPTIONAL FLOAT float_alp_1024;
  OPTIONAL DOUBLE double_alp_1024;
  OPTIONAL FLOAT float_alp_4096;
  OPTIONAL DOUBLE double_alp_4096;
  OPTIONAL FLOAT float_alp_32;
  OPTIONAL DOUBLE double_alp_32;
}

@alamb alamb Aug 4, 2026 •
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The layout:

andrewlamb@Andrews-MacBook-Pro-3:~/Software/parquet-testing$ ~/Software/arrow-rs/target/release/parquet-layout data/alp_extended.zstd.parquet
Details 
{
  "row_groups": [
    {
      "columns": [
        {
          "path": "float_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211391,
            "length": 12
          },
          "column_index": {
            "offset": 210367,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "double_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211403,
            "length": 14
          },
          "column_index": {
            "offset": 210395,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "float_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211417,
            "length": 14
          },
          "column_index": {
            "offset": 210431,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211431,
            "length": 14
          },
          "column_index": {
            "offset": 210459,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211445,
            "length": 14
          },
          "column_index": {
            "offset": 210495,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211459,
            "length": 14
          },
          "column_index": {
            "offset": 210523,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211473,
            "length": 14
          },
          "column_index": {
            "offset": 210559,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211487,
            "length": 14
          },
          "column_index": {
            "offset": 210587,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        }
      ],
      "row_count": 6144
    },
    {
      "columns": [
        {
          "path": "float_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211501,
            "length": 13
          },
          "column_index": {
            "offset": 210623,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "double_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211514,
            "length": 13
          },
          "column_index": {
            "offset": 210651,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "float_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211527,
            "length": 13
          },
          "column_index": {
            "offset": 210687,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211540,
            "length": 13
          },
          "column_index": {
            "offset": 210715,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211553,
            "length": 13
          },
          "column_index": {
            "offset": 210751,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211566,
            "length": 13
          },
          "column_index": {
            "offset": 210779,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211579,
            "length": 13
          },
          "column_index": {
            "offset": 210815,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211592,
            "length": 13
          },
          "column_index": {
            "offset": 210843,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        }
      ],
      "row_count": 1024
    },
    {
      "columns": [
        {
          "path": "float_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211605,
            "length": 12
          },
          "column_index": {
            "offset": 210879,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "double_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211617,
            "length": 12
          },
          "column_index": {
            "offset": 210907,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "float_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211629,
            "length": 12
          },
          "column_index": {
            "offset": 210943,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211641,
            "length": 12
          },
          "column_index": {
            "offset": 210971,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211653,
            "length": 12
          },
          "column_index": {
            "offset": 211007,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211665,
            "length": 12
          },
          "column_index": {
            "offset": 211035,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211677,
            "length": 13
          },
          "column_index": {
            "offset": 211071,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211690,
            "length": 13
          },
          "column_index": {
            "offset": 211099,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        }
      ],
      "row_count": 1024
    },
    {
      "columns": [
        {
          "path": "float_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211703,
            "length": 13
          },
          "column_index": {
            "offset": 211135,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "double_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211716,
            "length": 13
          },
          "column_index": {
            "offset": 211163,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "float_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211729,
            "length": 13
          },
          "column_index": {
            "offset": 211199,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211742,
            "length": 13
          },
          "column_index": {
            "offset": 211227,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211755,
            "length": 13
          },
          "column_index": {
            "offset": 211263,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211768,
            "length": 13
          },
          "column_index": {
            "offset": 211291,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211781,
            "length": 13
          },
          "column_index": {
            "offset": 211327,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_32",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 211794,
            "length": 13
          },
          "column_index": {
            "offset": 211355,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        }
      ],
      "row_count": 808
    }
  ],
  "footer": {
    "metadata_size": 3866
  }
}

@alamb alamb Aug 7, 2026

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Updated layout

Details 

{
  "row_groups": [
    {
      "columns": [
        {
          "path": "float_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213725,
            "length": 12
          },
          "column_index": {
            "offset": 212453,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "double_plain",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213737,
            "length": 14
          },
          "column_index": {
            "offset": 212481,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "ZSTD",
          "encodings": [
            "PLAIN",
            "RLE"
          ]
        },
        {
          "path": "float_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213751,
            "length": 14
          },
          "column_index": {
            "offset": 212517,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_1024",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213765,
            "length": 14
          },
          "column_index": {
            "offset": 212545,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "float_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213779,
            "length": 14
          },
          "column_index": {
            "offset": 212581,
            "length": 28
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
        {
          "path": "double_alp_4096",
          "has_offset_index": true,
          "has_column_index": true,
          "has_bloom_filter": false,
          "offset_index": {
            "offset": 213793,
            "length": 14
          },
          "column_index": {
            "offset": 212609,
            "length": 36
          },
          "bloom_filter": null,
          "compression": "UNCOMPRESSED",
          "encodings": [
            "RLE",
            "ALP"
          ]
        },
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@alamb alamb mentioned this pull request Aug 4, 2026
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@alamb

alamb commented Aug 4, 2026

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I have verified that the Rust reader from @sdf-jkl in apache/arrow-rs#9372 can read this file correctly

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alamb marked this pull request as ready for review August 4, 2026 14:24
@alamb alamb changed the title Add ALP test data Add single ALP test file (211KB, covers corner cases) Aug 4, 2026
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@vinooganesh

vinooganesh commented Aug 5, 2026

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I just ran this against the Java implementation from apache/parquet-java#3397. It reads the file fine, no changes needed on our end.

I decoded all six ALP columns and compared them against the matching PLAIN columns as raw bits (doubleToRawLongBits / floatToRawIntBits, so NaN and -0.0 compare properly). 53,952 values, everything matched. The special values at 1024-2047 all survive: both NaNs, +/-Inf, -0.0 at 2002, and the subnormal at 2003. The constant vector in row group 2 and the 8 nulls in the trailing partial vector are fine too.

It's worth calling out that the _32 columns caught something my own fixtures didn't. Java accepts log_vector_size 3-15, but everything I'd generated was 1024 or 4096, so vector size 32 had never actually been decoded from another writer's file until now. It works, but that path was untested.

There are a couple of things I noticed while poking at it, and all of them are fixable with a few extra columns rather than more data:

  • Every data page in the file is V1. Nothing exercises DataPageV2.
  • All the NaNs are canonical (0x7FF8000000000000 / 0x7FC00000), so nothing checks that a reader preserves NaN payloads.
  • The widest FOR bit width in the file is 18. @emkornfield asked us to cover values needing 63/64 bits after FOR on the Java PR, and that case isn't here.

I have fixtures for all three if they'd be helpful, but they'd be more columns on this file rather than separate ones. And I'm happy to contribute the Java-side conformance test to parquet-java once this lands on master.

@alamb

alamb commented Aug 5, 2026 •
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I have fixtures for all three if they'd be helpful, but they'd be more columns on this file rather than separate ones. And I'm happy to contribute the Java-side conformance test to parquet-java once this lands on master.

Thanks @vinooganesh

Every data page in the file is V1. Nothing exercises DataPageV2.

I think this is ok as I don't think the ALP encoding changes with the datapage format (and thus I don't think we need to cover that dimension in the ALP test cases)

All the NaNs are canonical (0x7FF8000000000000 / 0x7FC00000), so nothing checks that a reader preserves NaN payloads.

This is a good point -- I could update the file to also contain some non canonical Nans

The widest FOR bit width in the file is 18. @emkornfield asked us to cover values needing 63/64 bits after FOR on the Java PR, and that case isn't here.

This is a good point too -- I think I could update this file so that one of the groups has larger magnitude values that would use a large FOR.

I will wait for a few more days to see if there are other suggestions / comments about this PR, and then update the file per your suggestions

@alamb alamb mentioned this pull request Aug 7, 2026
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@alamb alamb changed the title Add single ALP test file (211KB, covers corner cases) Add single ALP test file (216KB, covers corner cases) Aug 7, 2026
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alamb commented Aug 7, 2026

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@vinooganesh I have updated the generator here to add some new Nan values and a small new row group that has a large FOR (18446744073709550676 for double)
apache/arrow@195ebd5

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Add example ALP files

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@alamb @vinooganesh