Liya Fan created ARROW-8169:
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Summary: [Java] Improve the performance of JDBC adapter by
allocating memory proactively
Key: ARROW-8169
URL: https://issues.apache.org/jira/browse/ARROW-8169
Project: Apache Arrow
Issue Type: Improvement
Components: Java
Reporter: Liya Fan
Assignee: Liya Fan
The current implementation use {{setSafe}} methods to dynamically allocate
memory if necessary. For fixed width vectors (which are frequently used in
JDBC), however, we can allocate memory proactively, since the vector size is
known as a configuration parameter. So for fixed width vectors, we can use
{{set}} methods instead.
This change leads to two benefits:
1. When processing each value, we no longer have to check vector capacity and
reallocate memroy if needed. This leads to better performance.
2. If we allow the memory to expand automatically (each time by 2x), the amount
of memory usually ends up being more than necessary. By allocating memory by
the configuration parameter, we allocate no more, or no less.
Benchmark results show notable performance improvements:
Before:
Benchmark Mode Cnt Score Error Units
JdbcAdapterBenchmarks.consumeBenchmark avgt 5 521.700 ± 4.837 us/op
After:
Benchmark Mode Cnt Score Error Units
JdbcAdapterBenchmarks.consumeBenchmark avgt 5 430.523 ± 9.932 us/op
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