87b498462b
### What changes were proposed in this pull request?
SPARK-30494's updated the `CreateViewCommand` code to implicitly drop cache when replacing an existing view. But, this change drops cache even when replacing a view having the same logical plan. A sequence of queries to reproduce this as follows;
```
// Spark v2.4.6+
scala> val df = spark.range(1).selectExpr("id a", "id b")
scala> df.cache()
scala> df.explain()
== Physical Plan ==
*(1) ColumnarToRow
+- InMemoryTableScan [a#2L, b#3L]
+- InMemoryRelation [a#2L, b#3L], StorageLevel(disk, memory, deserialized, 1 replicas)
+- *(1) Project [id#0L AS a#2L, id#0L AS b#3L]
+- *(1) Range (0, 1, step=1, splits=4)
scala> df.createOrReplaceTempView("t")
scala> sql("select * from t").explain()
== Physical Plan ==
*(1) ColumnarToRow
+- InMemoryTableScan [a#2L, b#3L]
+- InMemoryRelation [a#2L, b#3L], StorageLevel(disk, memory, deserialized, 1 replicas)
+- *(1) Project [id#0L AS a#2L, id#0L AS b#3L]
+- *(1) Range (0, 1, step=1, splits=4)
// If one re-runs the same query `df.createOrReplaceTempView("t")`, the cache's swept away
scala> df.createOrReplaceTempView("t")
scala> sql("select * from t").explain()
== Physical Plan ==
*(1) Project [id#0L AS a#2L, id#0L AS b#3L]
+- *(1) Range (0, 1, step=1, splits=4)
// Until v2.4.6
scala> val df = spark.range(1).selectExpr("id a", "id b")
scala> df.cache()
scala> df.createOrReplaceTempView("t")
scala> sql("select * from t").explain()
20/10/23 22:33:42 WARN ObjectStore: Failed to get database global_temp, returning NoSuchObjectException
== Physical Plan ==
*(1) InMemoryTableScan [a#2L, b#3L]
+- InMemoryRelation [a#2L, b#3L], StorageLevel(disk, memory, deserialized, 1 replicas)
+- *(1) Project [id#0L AS a#2L, id#0L AS b#3L]
+- *(1) Range (0, 1, step=1, splits=4)
scala> df.createOrReplaceTempView("t")
scala> sql("select * from t").explain()
== Physical Plan ==
*(1) InMemoryTableScan [a#2L, b#3L]
+- InMemoryRelation [a#2L, b#3L], StorageLevel(disk, memory, deserialized, 1 replicas)
+- *(1) Project [id#0L AS a#2L, id#0L AS b#3L]
+- *(1) Range (0, 1, step=1, splits=4)
```
### Why are the changes needed?
bugfix.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Added tests.
Closes #30140 from maropu/FixBugInReplaceView.
Authored-by: Takeshi Yamamuro <yamamuro@apache.org>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
|
||
|---|---|---|
| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-api-docs.py | ||
| gen-sql-config-docs.py | ||
| gen-sql-functions-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.