d65f534c5a
### What changes were proposed in this pull request?
With benchmark original, where the timestamp values are valid to the new parser
the result is
```scala
[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
```
When we modify the benchmark to
```scala
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()
}
```
where the timestamp values are invalid for the new parser which causes a fallback to legacy parser(2.4).
the result is
```scala
[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
```
About 10x perf-regression
BUT if we modify the timestamp pattern to `....HH:mm:ss[.SSS][XXX]` which make all timestamp values valid for the new parser to prohibit fallback, the result is
```scala
[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
```
### Why are the changes needed?
Fix performance regression.
### Does this PR introduce any user-facing change?
NO
### How was this patch tested?
new tests added.
Closes #28181 from yaooqinn/SPARK-31414.
Authored-by: Kent Yao <yaooqinn@hotmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
|
||
|---|---|---|
| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-api-docs.py | ||
| gen-sql-config-docs.py | ||
| mkdocs.yml | ||
| README.md | ||
Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes extensions that allow users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allow users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.
Running ./sql/create-docs.sh generates SQL documentation for built-in functions under sql/site, and SQL configuration documentation that gets included as part of configuration.md in the main docs directory.