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Posted to issues@arrow.apache.org by "Hattonuri (via GitHub)" <gi...@apache.org> on 2023/11/26 17:41:40 UTC
[I] [C++] Decimal FromBigEndian start to use ByteSwap [arrow]
Hattonuri opened a new issue, #38886:
URL: https://github.com/apache/arrow/issues/38886
### Describe the enhancement requested
When arrow parses decimal from big endian (and it happens on every element read from parquet for example), it does this in a very complex way
https://github.com/apache/arrow/blob/eb5de184a7e5d02f98526332ace54250417bd232/cpp/src/arrow/util/decimal.cc#L745-L796
I assume that it's because FromBigEndian function uses ByteSwap which lacks fast version(those are in switch case)
https://github.com/apache/arrow/blob/eb5de184a7e5d02f98526332ace54250417bd232/cpp/src/arrow/util/endian.h#L96-L119
But ByteSwap on 16 byte length can be written using two ByteSwaps of 8 length as here https://stackoverflow.com/questions/8004790/how-to-change-byte-order-of-128-bit-number
### Component(s)
C++
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Re: [I] [C++] Decimal FromBigEndian start to use ByteSwap [arrow]
Posted by "Hattonuri (via GitHub)" <gi...@apache.org>.
Hattonuri commented on issue #38886:
URL: https://github.com/apache/arrow/issues/38886#issuecomment-1837529660
I understood that when the length of FLBA and decimal are equal almost the same happen
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Re: [I] [C++] Decimal FromBigEndian start to use ByteSwap [arrow]
Posted by "Hattonuri (via GitHub)" <gi...@apache.org>.
Hattonuri closed issue #38886: [C++] Decimal FromBigEndian start to use ByteSwap
URL: https://github.com/apache/arrow/issues/38886
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Re: [I] [C++] Decimal FromBigEndian start to use ByteSwap [arrow]
Posted by "Hattonuri (via GitHub)" <gi...@apache.org>.
Hattonuri commented on issue #38886:
URL: https://github.com/apache/arrow/issues/38886#issuecomment-1826844911
This issue probably connected with previous issue about too slow RawBytesToDecimalBytes https://github.com/apache/arrow/issues/38881
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