Csaba Ringhofer created IMPALA-12142:
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Summary: Default fetch_size of 10240 is suboptimal
Key: IMPALA-12142
URL: https://issues.apache.org/jira/browse/IMPALA-12142
Project: IMPALA
Issue Type: Improvement
Components: Clients
Reporter: Csaba Ringhofer
While working on IMPALA-12138 it turned out that the default settings of
batch_size=1024 and fetch_size=10240 are not ideal for the coordinator
(RowMaterializationTimer). My guess for the cause is that HS2 results vectors
are rounded up to power of 2 sizes leading to extra allocations and copying.
query: select * from tpch_parquet.lineitem
RowMaterializationTimer (before and after IMPALA-12138)
fetch_size=10240: 3.6s ->3.2s
fetch_size=8192: 2.8s->2.6s
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