[
https://issues.apache.org/jira/browse/SPARK-31414?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Wenchen Fan resolved SPARK-31414.
---------------------------------
Fix Version/s: 3.0.0
Resolution: Fixed
Issue resolved by pull request 28181
[https://github.com/apache/spark/pull/28181]
> Performance regression with new TimestampFormatter for json and csv
> -------------------------------------------------------------------
>
> Key: SPARK-31414
> URL: https://issues.apache.org/jira/browse/SPARK-31414
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Kent Yao
> Assignee: Kent Yao
> Priority: Major
> Fix For: 3.0.0
>
>
> with benchmark original, where the timestamp values are valid to new parser
> the result is
> {code:java}
> [info] Running benchmark: Read dates and timestamps
> [info] Running case: timestamp strings
> [info] Stopped after 3 iterations, 5781 ms
> [info] Running case: parse timestamps from Dataset[String]
> [info] Stopped after 3 iterations, 44764 ms
> [info] Running case: infer timestamps from Dataset[String]
> [info] Stopped after 3 iterations, 93764 ms
> [info] Running case: from_json(timestamp)
> [info] Stopped after 3 iterations, 59021 ms
> {code}
> when we modify the benchmark to
> {code:java}
> def timestampStr: Dataset[String] = {
> spark.range(0, rowsNum, 1, 1).mapPartitions { iter =>
> iter.map(i => s"""{"timestamp":"1970-01-01T01:02:03.${i % 100}"}""")
> }.select($"value".as("timestamp")).as[String]
> }
> readBench.addCase("timestamp strings", numIters) { _ =>
> timestampStr.noop()
> }
> readBench.addCase("parse timestamps from Dataset[String]", numIters) {
> _ =>
> spark.read.schema(tsSchema).json(timestampStr).noop()
> }
> readBench.addCase("infer timestamps from Dataset[String]", numIters) {
> _ =>
> spark.read.json(timestampStr).noop()
> }
> {code}
> where the timestamp values are invalid for the new parser which cause
> fallback to legacy parser.
> the result is
> {code:java}
> [info] Running benchmark: Read dates and timestamps
> [info] Running case: timestamp strings
> [info] Stopped after 3 iterations, 5623 ms
> [info] Running case: parse timestamps from Dataset[String]
> [info] Stopped after 3 iterations, 506637 ms
> [info] Running case: infer timestamps from Dataset[String]
> [info] Stopped after 3 iterations, 509076 ms
> {code}
> About 10x perf-regression
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