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Posted to github@arrow.apache.org by "viirya (via GitHub)" <gi...@apache.org> on 2023/04/12 20:00:58 UTC
[GitHub] [arrow-datafusion] viirya opened a new pull request, #5980: Decimal multiply kernel should not cause precision loss
viirya opened a new pull request, #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980
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Closes #5674.
Closes #3387.
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[GitHub] [arrow-datafusion] Dandandan commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1514305301
FYI @mingmwang @andygrove this PR also has some effect on performance, as casting is changed (mostly reduced).
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[GitHub] [arrow-datafusion] viirya commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1510496247
There is a compilation error. Going to fix it at #6029.
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[GitHub] [arrow-datafusion] alamb commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1520543719
🎉
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[GitHub] [arrow-datafusion] Dandandan commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1514338925
Ran the benchmarks for TPCH(SF=1) in memory.
Performance is mostly the same, except a ~30% improvement for q1 compared to main 🚀
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[GitHub] [arrow-datafusion] viirya commented on a diff in pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on code in PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#discussion_r1169177389
##########
datafusion/physical-expr/src/expressions/binary.rs:
##########
@@ -4801,18 +4878,18 @@ mod tests {
// subtract: decimal array subtract int32 array
let schema = Arc::new(Schema::new(vec![
- Field::new("b", DataType::Int32, true),
Field::new("a", DataType::Decimal128(10, 2), true),
Review Comment:
Previously the field order is incorrect. But as we did coerce type on both side of the op anyway, so it still worked before. Now we don't coerce the decimal field (which is wrongly bound to Int32Array) before into binary expression, so wrong field causes an error.
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[GitHub] [arrow-datafusion] Dandandan commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1512599257
I wonder if this already fixes https://github.com/apache/arrow-datafusion/issues/4024
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[GitHub] [arrow-datafusion] viirya commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1512117023
cc @alamb @liukun4515
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[GitHub] [arrow-datafusion] viirya commented on a diff in pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on code in PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#discussion_r1169167115
##########
datafusion/physical-expr/src/expressions/binary.rs:
##########
@@ -3258,7 +3308,17 @@ mod tests {
Arc::new(schema),
vec![Arc::new(a), Arc::new(b)],
Operator::Divide,
- create_decimal_array(&[Some(0), None, None, Some(1), Some(1)], 10, 0),
+ create_decimal_array(
+ &[
+ Some(99193548387), // 0.99193548387
+ None,
+ None,
+ Some(100813008130), // 1.0081300813
+ Some(100000000000), // 1.0
+ ],
+ 21,
+ 11,
Review Comment:
Previously, this division losses precision. Now we get it back.
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[GitHub] [arrow-datafusion] viirya commented on a diff in pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on code in PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#discussion_r1169216648
##########
datafusion/core/tests/sqllogictests/src/engines/conversion.rs:
##########
@@ -74,9 +75,9 @@ pub fn f64_to_str(value: f64) -> String {
}
}
-pub fn i128_to_str(value: i128, scale: u32) -> String {
+pub fn i128_to_str(value: i128, precision: &u8, scale: &i8) -> String {
big_decimal_to_str(
- BigDecimal::from_str(&Decimal::from_i128_with_scale(value, scale).to_string())
+ BigDecimal::from_str(&Decimal128Type::format_decimal(value, *precision, *scale))
Review Comment:
See https://github.com/apache/arrow-datafusion/pull/5675/files#r1148798935
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[GitHub] [arrow-datafusion] Dandandan commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1514299232
Let's wait ~24hrs so other reviewers can have a chance.
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[GitHub] [arrow-datafusion] viirya commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1512622096
> I wonder if this already fixes #4024
Yea, just verified locally that this can pass `verify_q6`.
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[GitHub] [arrow-datafusion] viirya commented on a diff in pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on code in PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#discussion_r1169177870
##########
datafusion/core/tests/sqllogictests/test_files/tpch.slt:
##########
@@ -118,14 +118,18 @@ CREATE EXTERNAL TABLE IF NOT EXISTS supplier (
# q1
+# The decimal calculation `sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) as sum_charge` actually causes
+# overflow on decimal multiplication. Because the kernel DataFusion uses doesn't allow precision loss, we need
+# a cast to decimal(12,2) to avoid the overflow. We can get rid of it once we can use new multiply kernel from
+# arrow-rs which allows precision-loss.
query TTRRRRRRRI
select
l_returnflag,
l_linestatus,
sum(l_quantity) as sum_qty,
sum(l_extendedprice) as sum_base_price,
sum(l_extendedprice * (1 - l_discount)) as sum_disc_price,
- sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) as sum_charge,
+ sum(cast(l_extendedprice as decimal(12,2)) * (1 - l_discount) * (1 + l_tax)) as sum_charge,
Review Comment:
See https://github.com/apache/arrow-datafusion/pull/5675/files#r1148798281
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[GitHub] [arrow-datafusion] Dandandan merged pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan merged PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980
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[GitHub] [arrow-datafusion] viirya commented on a diff in pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on code in PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#discussion_r1169216170
##########
benchmarks/queries/q8.sql:
##########
@@ -1,9 +1,9 @@
select
o_year,
- sum(case
- when nation = 'BRAZIL' then volume
- else 0
- end) / sum(volume) as mkt_share
+ cast(cast(sum(case
+ when nation = 'BRAZIL' then volume
+ else 0
+ end) as decimal(12,2)) / cast(sum(volume) as decimal(12,2)) as decimal(15,2)) as mkt_share
Review Comment:
See https://github.com/apache/arrow-datafusion/pull/5675/files#r1152896889
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[GitHub] [arrow-datafusion] viirya commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1513592308
Thanks @Dandandan
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[GitHub] [arrow-datafusion] viirya commented on pull request #5980: Decimal multiply kernel should not cause precision loss
Posted by "viirya (via GitHub)" <gi...@apache.org>.
viirya commented on PR #5980:
URL: https://github.com/apache/arrow-datafusion/pull/5980#issuecomment-1505857277
Different to #5675, this doesn't add new expression node `PromotePrecision` and defers decimal type coercion to the phase of math expression evaluation.
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