hive partitioning predicate isn't applied before reading

[lmocsi]

hive partitioning predicate isn't applied before reading

[ritchie46]

Can it be, that the order of the filtering criteria determines if partition filtering will be used or not?

I think this is the case. We should keep hive partitioned predicates separate.

@nameexhaustion another data point.

[ritchie46]

Hmm.. We did some checks and we do apply predicate pushdown based on hive partitions. Can you create a that shows the difference? That helps us to fix it.

[lmocsi]

Create a what? A test dataset?
There is one similar that can be created: apache/arrow#39768
But I do not know if you can reproduce the problem on that.
How could I test it on the real data?

[deanm0000]

@ritchie46 See #13908 and subsequently #14244

@lmocsi it would be more helpful if you brought up the old issues from the start. Did it work in 0.20.7, which is the first version that the above PR was in?

[lmocsi]

The performance difference is there with older versions (eg. 0.20.3), as well.
I did not go further back in time.

[lmocsi]

Can it be, that datetime partition name formatting is confusing scan_parquet?
Thinking of the 00%3A00%3A00 part.
Eg:
/my_path/my_table/CALENDAR_DATE=2019-01-01 00%3A00%3A00/part-00000-35c18ead-whatever.c000.snappy.parquet

[ritchie46]

Create a what? A test dataset?

A full reproducable example that shows the problem. So test data and the query that goes with it.

[lmocsi]

Create a what? A test dataset?

A full reproducable example that shows the problem. So test data and the query that goes with it.

I tried, but it is not clear, which part of the dataset the error comes from.
Unfortunately I cannot disclose the dataset.
Is there a way I can test, what you'd be testing on a full reproducable example?

[ritchie46]

Try to create some fake data with the same hive partition schemas. It probably is only the hive partitions and the query that's important.

[lmocsi]

See the sample data creation and reading up:

#create data
import polars as pl
from faker import Faker
import random as rnd
from datetime import datetime,date
import pyarrow.dataset as ds

print(f"polars version: {pl.__version__}")

def ido():
    return datetime.now().strftime('%Y.%m.%d. %H:%M:%S')

fake = Faker()

print(ido(),'Started')

path = '/mypath/'
dflen = 10000000
df = pl.DataFrame({'ID': pl.Series(fake.unique.random_int(min=13127924000, max=14127924000) for i in range(dflen)),
                   'BA_ID': pl.Series(fake.unique.random_int(min=2, max=2585456410) for i in range(dflen)),
                   'PART_ID': pl.Series(fake.unique.random_int(min=2163520, max=16320804) for i in range(dflen)),
                   'CU_ID': pl.Series(rnd.choice([1096, 3342, 3374, 4272, 3098, 3099]) for i in range(dflen)),
                   'DEA_ID': pl.Series(fake.unique.random_int(min=996000, max=53237133) for i in range(dflen)),
                   'AM_CY': pl.Series(fake.pyfloat(min_value=10000.0, max_value=990000.0, right_digits=1) for i in range(dflen)),
                   'CR_FL': pl.Series(rnd.choice(['Y', 'N']) for i in range(dflen)),
                   'PA_COM': pl.Series(rnd.choice(["######", None]) for i in range(dflen)),
                   'CO_TE': pl.Series(rnd.choice(["######", "A:Techn. part######", " -5755.00 MAD -5755.0"]) for i in range(dflen)),
                   'OT_AC': pl.Series(rnd.choice(["121223234545565678788989", "111122224444555577778888",  None]) for i in range(dflen)),
                   'OP_AC_NA': pl.Series(rnd.choice(["Donald Arthur Biden###########", "Joe William Trump#############",  None]) for i in range(dflen)),
                   'DWS_ID': pl.Series(rnd.choice([198, 1395, 5121, 2473]) for i in range(dflen)),
                   'ADT_ID': pl.Series(rnd.choice([570, 1309, 1680, 1798, 1916, 13856, 355136]) for i in range(dflen)),
                   'ADC_ID': pl.Series(rnd.choice([1019, 1134, 1455]) for i in range(dflen)),
                   'ADK_ID': pl.Series(rnd.choice([2058, 2185, 160279, 240274]) for i in range(dflen)),
                   'ABDO_ID': pl.Series(rnd.choice([2, 31248967]) for i in range(dflen)),
                   'ADS_ID': pl.Series(rnd.choice([1271, 1265, 1399, 1342, 1652, 1266]) for i in range(dflen)),
                   'INT_FL': pl.Series(rnd.choice(['Y', None]) for i in range(dflen)),
                   'MN_DIR': pl.Series(rnd.choice(['INT', 'DOM']) for i in range(dflen)),
                   'ADC_ID': pl.Series(rnd.choice([2, 2688, 2689, 24605]) for i in range(dflen)),
                   'ADO_ID': pl.Series(rnd.choice([2, 3126]) for i in range(dflen)),
                   'REF': pl.Series(rnd.choice(['12345679801','AD789789_12345645','DAS7894561230315','12345678','81051314_239_02_01_00_4566']) for i in range(dflen)),
                   'SEC_ID': pl.Series(rnd.choice([2, 93708]) for i in range(dflen)),
                   'ADL_ID': pl.Series(rnd.choice([2, 1125, 1134, 1364, 20834]) for i in range(dflen)),
                   'CH_ID': pl.Series(rnd.choice([50141, 50016, 49904, 49838, None]) for i in range(dflen)),
                   #'CALENDAR_DATE': pl.Series(fake.date_between_dates(date(2023,1,1),date(2024,4,30)) for i in range(dflen)), # calendar_date:date -> scan_parquet reads it very fast
                   'CALENDAR_DATE': pl.Series(fake.date_between_dates(datetime(2023,1,1),datetime(2024,4,30)) for i in range(dflen)),
                  }).with_columns(AM=pl.col('AM_CY'))

print(ido(),dflen,'records created')

ds.write_dataset(
        df.to_arrow(),
        path+'my_transaction',
        format="parquet",
        partitioning=["CALENDAR_DATE"],
        partitioning_flavor="hive",
        existing_data_behavior="delete_matching",
    )

print(ido(),'finished')
# 2024.06.19. 17:26:12 Started
# 2024.06.19. 17:41:46 10000000 records created
# 2024.06.19. 17:43:02 finished

Then reading the data shows the difference: scan_pyarrow_dataset runs in 2 seconds, while scan_parquet runs in 21 seconds:

import polars as pl
from datetime import datetime
import pyarrow.dataset as ds

print(f"polars version: {pl.__version__}")

def ido():
    return datetime.now().strftime('%Y.%m.%d. %H:%M:%S')

parq_path = '/mypath/'
ext = '/**/*.parquet'

tr = pl.scan_pyarrow_dataset(ds.dataset(parq_path+"my_transaction", partitioning='hive'))
df = (tr.filter((pl.col('CALENDAR_DATE').is_between(pl.lit('2023-12-01'), pl.lit('2023-12-31'))) &
                   (pl.col('CR_FL') == 'I') &
                   (pl.col('SEC_ID') > 3) &
                   (pl.col('ADL_ID') == 2905) &
                   (~pl.col('PART_ID').is_in([5086634, 2149316, 6031676])) &
                   (pl.col('ADT_ID') != 7010)
                   )
           .select('PART_ID').unique()
           .rename({'PART_ID':'PARTY_ID'})
           .with_columns(pl.lit(1).alias('LU_NEXT_FL'))
         )
print(ido(),'scan_pyarrow_dataset started') # 2 sec
df.collect()
print(ido(),'scan_pyarrow_dataset finished')

# explain plan:
# WITH_COLUMNS:
#  [dyn int: 1.alias("LU_NEXT_FL")] 
#   RENAME
#     UNIQUE[maintain_order: false, keep_strategy: Any] BY None
#       simple π 1/6 ["PART_ID"]
#           PYTHON SCAN 
#           PROJECT 6/26 COLUMNS
#           SELECTION: [([([([([([(col("ADL_ID")) == (2905)]) & (col("PART_ID").is_in([Series]).not())]) & ([(col("SEC_ID")) > (3)])]) & ([(col("ADT_ID")) != (7010)])]) & ([(col("CR_FL")) == (String(I))])]) & (col("CALENDAR_DATE").is_between([String(2023-12-01), String(2023-12-31)]))]


tr2 = pl.scan_parquet(parq_path+"my_transaction"+ext)
df2 = (tr2.filter((pl.col('CALENDAR_DATE').is_between(pl.lit('2023-12-01'), pl.lit('2023-12-31'))) &
                   (pl.col('CR_FL') == 'I') &
                   (pl.col('SEC_ID') > 3) &
                   (pl.col('ADL_ID') == 2905) &
                   (~pl.col('PART_ID').is_in([5086634, 2149316, 6031676])) &
                   (pl.col('ADT_ID') != 7010)
                   )
           .select('PART_ID').unique()
           .rename({'PART_ID':'PARTY_ID'})
           .with_columns(pl.lit(1).alias('LU_NEXT_FL'))
         )
print(ido(),'scan_parquet started') # 21 sec
df2.collect()
print(ido(),'scan_parquet finished')

# explain plan:
 # WITH_COLUMNS:
 # [dyn int: 1.alias("LU_NEXT_FL")] 
 #  RENAME
 #    UNIQUE[maintain_order: false, keep_strategy: Any] BY None
 #      simple π 1/6 ["PART_ID"]
 #          Parquet SCAN 485 files: first file: /mypath/my_transaction/CALENDAR_DATE=2023-01-01/part-0.parquet
 #          PROJECT 6/26 COLUMNS
 #          SELECTION: [([([([([([(col("ADL_ID")) == (2905)]) & ([(col("ADT_ID")) != (7010)])]) & (col("CALENDAR_DATE").is_between([String(2023-12-01), String(2023-12-31)]))]) & ([(col("SEC_ID")) > (3)])]) & (col("PART_ID").is_in([Series]).not())]) & ([(col("CR_FL")) == (String(I))])]

[lmocsi]

One small addition: in the data creation part the CALENDAR_DATE field should be calculated like this:

   'CALENDAR_DATE': pl.Series(fake.date_time_between_dates(datetime(2023,1,1),datetime(2024,4,30)) for i in range(dflen)).dt.truncate('1d'),