1b7443bd9a
### What changes were proposed in this pull request?
This PR added a physical rule to remove redundant project nodes. A `ProjectExec` is redundant when
1. It has the same output attributes and order as its child's output when ordering of these attributes is required.
2. It has the same output attributes as its child's output when attribute output ordering is not required.
For example:
After Filter:
```
== Physical Plan ==
*(1) Project [a#14L, b#15L, c#16, key#17]
+- *(1) Filter (isnotnull(a#14L) AND (a#14L > 5))
+- *(1) ColumnarToRow
+- FileScan parquet [a#14L,b#15L,c#16,key#17]
```
The `Project a#14L, b#15L, c#16, key#17` is redundant because its output is exactly the same as filter's output.
Before Aggregate:
```
== Physical Plan ==
*(2) HashAggregate(keys=[key#17], functions=[sum(a#14L), last(b#15L, false)], output=[sum_a#39L, key#17, last_b#41L])
+- Exchange hashpartitioning(key#17, 5), true, [id=#77]
+- *(1) HashAggregate(keys=[key#17], functions=[partial_sum(a#14L), partial_last(b#15L, false)], output=[key#17, sum#49L, last#50L, valueSet#51])
+- *(1) Project [key#17, a#14L, b#15L]
+- *(1) Filter (isnotnull(a#14L) AND (a#14L > 100))
+- *(1) ColumnarToRow
+- FileScan parquet [a#14L,b#15L,key#17]
```
The `Project key#17, a#14L, b#15L` is redundant because hash aggregate doesn't require child plan's output to be in a specific order.
### Why are the changes needed?
It removes unnecessary query nodes and makes query plan cleaner.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Unit tests
Closes #29031 from allisonwang-db/remove-project.
Lead-authored-by: allisonwang-db <66282705+allisonwang-db@users.noreply.github.com>
Co-authored-by: allisonwang-db <allison.wang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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|---|---|---|
| .. | ||
| 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.