[GitHub] [arrow-site] hatemhelal commented on a change in pull request #19: ARROW-6419: [Website] Blog post about Parquet C++ read performance improvements in Arrow 0.15

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hatemhelal commented on a change in pull request #19: ARROW-6419: [Website] Blog post about Parquet C++ read performance improvements in Arrow 0.15
URL: https://github.com/apache/arrow-site/pull/19#discussion_r321293620
 
 

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 File path: _posts/2019-09-03-faster-strings-cpp-parquet.md
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+---
+layout: post
+title: "Faster C++ Apache Parquet performance on dictionary-encoded string data coming in Apache Arrow 0.15"
+date: "2019-09-05 00:00:00 -0600"
+author: Wes McKinney
+categories: [application]
+---
+<!--
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+
+We have been implementing a series of optimizations in the Apache Parquet C++
+internals to improve read and write efficiency (both performance and memory
+use) for Arrow columnar binary and string data, with new "native" support for
+Arrow's dictionary types. This should have a big impact on users of the C++,
+MATLAB, Python, R, and Ruby interfaces to Parquet files.
+
+This post reviews work that was done and shows benchmarks comparing Arrow
+0.12.1 with the current development version (to be released soon as Arrow
+0.15.0).
+
+# Summary of work
+
+One of the largest and most complex optimizations involves encoding and
+decoding Parquet files' internal dictionary-encoded data streams to and from
+Arrow's in-memory dictionary-encoded `DictionaryArray`
+representation. Dictionary encoding is a compression strategy in Parquet, and
+there is no formal "dictionary" or "categorical" type. I will go into more
+detail about this below.
+
+Some of the particular JIRA issues related to this work include:
+
+- Vectorize comparators for computing statistics ([PARQUET-1523][1])
+- Read binary directly data directly into DictionaryBuilder<T>
+  ([ARROW-3769][2])
+- Writing Parquet's dictionary indices directly into DictionaryBuilder<T>
+  ([ARROW-3772][3])
+- Write dense (non-dictionary) Arrow arrays directly into Parquet data encoders
+  ([ARROW-6152][4])
+- Direct writing of arrow::DictionaryArray to Parquet column writers ([ARROW-3246][5])
+- Supporting changing dictionaries ([ARROW-3144][6])
+- Internal IO optimizations and improved raw `BYTE_ARRAY` encoding performance
+  ([ARROW-4398][7])
+
+One of the challenges of developing the Parquet C++ library is that we
+maintain low-level read and write APIs that do not involve the Arrow columnar
+data structures. So we have had to take care to do Arrow-related optimizations
 
 Review comment:
   ```suggestion
   data structures. So we have had to take care implement Arrow-related optimizations
   ```

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