8f0fef1843
### What changes were proposed in this pull request?
Add support for full outer join inside shuffled hash join. Currently if the query is a full outer join, we only use sort merge join as the physical operator. However it can be CPU and IO intensive in case input table is large for sort merge join. Shuffled hash join on the other hand saves the sort CPU and IO compared to sort merge join, especially when table is large.
This PR implements the full outer join as followed:
* Process rows from stream side by looking up hash relation, and mark the matched rows from build side by:
* for joining with unique key, a `BitSet` is used to record matched rows from build side (`key index` to represent each row)
* for joining with non-unique key, a `HashSet[Long]` is used to record matched rows from build side (`key index` + `value index` to represent each row).
`key index` is defined as the index into key addressing array `longArray` in `BytesToBytesMap`.
`value index` is defined as the iterator index of values for same key.
* Process rows from build side by iterating hash relation, and filter out rows from build side being looked up already (done in `ShuffledHashJoinExec.fullOuterJoin`)
For context, this PR was originally implemented as followed (up to commit
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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.