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Posted to issues@arrow.apache.org by "mapleFU (via GitHub)" <gi...@apache.org> on 2023/07/07 13:58:29 UTC
[GitHub] [arrow] mapleFU opened a new issue, #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
mapleFU opened a new issue, #36548:
URL: https://github.com/apache/arrow/issues/36548
### Describe the enhancement requested
When I go through the code in `Statistics` and `PageIndex`, I found the argument of builder contains a `::arrow::MemoryPool`, and most caller didn't passing it. Like:
Builder:
```C++
/// \brief Typed version of Statistics::Make
template <typename DType>
std::shared_ptr<TypedStatistics<DType>> MakeStatistics(
const ColumnDescriptor* descr,
::arrow::MemoryPool* pool = ::arrow::default_memory_pool()) {
return std::static_pointer_cast<TypedStatistics<DType>>(Statistics::Make(descr, pool));
}
```
Caller:
```c++
template <typename DType>
static std::shared_ptr<Statistics> MakeTypedColumnStats(
const format::ColumnMetaData& metadata, const ColumnDescriptor* descr) {
// If ColumnOrder is defined, return max_value and min_value
if (descr->column_order().get_order() == ColumnOrder::TYPE_DEFINED_ORDER) {
return MakeStatistics<DType>(
descr, metadata.statistics.min_value, metadata.statistics.max_value,
metadata.num_values - metadata.statistics.null_count,
metadata.statistics.null_count, metadata.statistics.distinct_count,
metadata.statistics.__isset.max_value || metadata.statistics.__isset.min_value,
metadata.statistics.__isset.null_count,
metadata.statistics.__isset.distinct_count);
}
// Default behavior
return MakeStatistics<DType>(
descr, metadata.statistics.min, metadata.statistics.max,
metadata.num_values - metadata.statistics.null_count,
metadata.statistics.null_count, metadata.statistics.distinct_count,
metadata.statistics.__isset.max || metadata.statistics.__isset.min,
metadata.statistics.__isset.null_count, metadata.statistics.__isset.distinct_count);
}
```
However, I found that `::arrow::MemoryPool` is not useful here, it's used to build the `PlainEncoder` and Encode the min-max, and only used with little time and building small chunk of memory, so, do we need passing `MemoryPool` to `Statistics`? Or just using default one is ok?
### Component(s)
C++, Parquet
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[GitHub] [arrow] wgtmac commented on issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
Posted by "wgtmac (via GitHub)" <gi...@apache.org>.
wgtmac commented on issue #36548:
URL: https://github.com/apache/arrow/issues/36548#issuecomment-1625562741
You are right, memory pool is only used to allocate (temporary) buffer for encoding min/max values. In the page index, all min/max values are stored in the thrift ColumnIndex objects which we cannot control.
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Re: [I] [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex? [arrow]
Posted by "mapleFU (via GitHub)" <gi...@apache.org>.
mapleFU closed issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
URL: https://github.com/apache/arrow/issues/36548
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[GitHub] [arrow] mapleFU commented on issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
Posted by "mapleFU (via GitHub)" <gi...@apache.org>.
mapleFU commented on issue #36548:
URL: https://github.com/apache/arrow/issues/36548#issuecomment-1625459167
cc @pitrou @wgtmac @felipecrv
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[GitHub] [arrow] mapleFU commented on issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
Posted by "mapleFU (via GitHub)" <gi...@apache.org>.
mapleFU commented on issue #36548:
URL: https://github.com/apache/arrow/issues/36548#issuecomment-1626640744
Well, I mean that most of time using default is enough here, because it only allocates little memory(If encoded content is not too large)
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[GitHub] [arrow] felipecrv commented on issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
Posted by "felipecrv (via GitHub)" <gi...@apache.org>.
felipecrv commented on issue #36548:
URL: https://github.com/apache/arrow/issues/36548#issuecomment-1625782269
Pass it to the small allocations now and later, when those other functions learn to take a MemoryPool, we can pass it to them as well.
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[GitHub] [arrow] pitrou commented on issue #36548: [C++][Parquet] Do we need `MemoryPool` in Statistics and PageIndex?
Posted by "pitrou (via GitHub)" <gi...@apache.org>.
pitrou commented on issue #36548:
URL: https://github.com/apache/arrow/issues/36548#issuecomment-1625598512
Well, we should make sure we propagate the MemoryPool instead of removing that argument.
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