Zhengqiang Duan created COMDEV-489:
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Summary: Apache ShardingSphere: Support more MySQL SQLStatement
conversion to SqlNode
Key: COMDEV-489
URL: https://issues.apache.org/jira/browse/COMDEV-489
Project: Community Development
Issue Type: Improvement
Components: GSoC/Mentoring ideas
Reporter: Zhengqiang Duan
h2. Apache ShardingSphere
Apache ShardingSphere is positioned as a Database Plus, and aims at building a
standard layer and ecosystem above heterogeneous databases. It focuses on how
to reuse existing databases and their respective upper layer, rather than
creating a new database. The goal is to minimize or eliminate the challenges
caused by underlying databases fragmentation.
{*}Page{*}:
[https://shardingsphere.apache.org|https://shardingsphere.apache.org/]
{*}Github{*}: [https://github.com/apache/shardingsphere]
h2. Background
ShardingSphere parser engine helps users parse a SQL to get the AST (Abstract
Syntax Tree) and visit this tree to get SQLStatement (Java Object). At present,
this parser engine can handle SQLs for `MySQL`, `PostgreSQL`, `SQLServer`,
`openGauss` and `Oracle`, which means we have to understand different database
dialect SQLs.
{*}More details{*}:
[https://shardingsphere.apache.org/document/current/en/reference/sharding/parse/]
h2. Task
This issue is to solve the unsupported postgres sql about alter in [this
file|https://github.com/apache/shardingsphere/blob/master/shardingsphere-test/shardingsphere-parser-test/src/main/resources/sql/unsupported/unsupported.xml]
. * CALL
* DO
* DROP FUNCTION
* DROP INDEX
* DROP INSTANCE RULE
* DROP REWRITE RULE
* EXECUTE
* EXPLAIN
* FETCH
* FETCH ABSOLUTE
* FETCH ALL
* FETCH BACKWARD
* FETCH FIRST
* FETCH LAST
* FETCH NEXT
* FETCH PRIOR
* FETCH RELATIVE
* IMPORT FOREIGN SCHEMA
You can *learn more*
[here|https://www.postgresql.org/docs/current/sql-commands.html]. *
You may need to try to get why it's not supported.(antlr4 grammar? or not
implement visit method) You can use [antlr4
plugins|https://plugins.jetbrains.com/plugin/7358-antlr-v4] to help you to
analyze. You may need to visit [an official
doc|https://www.postgresql.org/docs/current/sql-commands.html] to check the
grammar.
* After you fix it, remember to add a new corresponding SQL case in [SQL
Cases|https://github.com/apache/shardingsphere/tree/master/shardingsphere-test/shardingsphere-parser-test/src/main/resources/sql/supported]
and expected parsed result in [Expected Statment
XML|https://github.com/apache/shardingsphere/tree/master/shardingsphere-test/shardingsphere-parser-test/src/main/resources/case].
* Run
[SQLParserParameterizedTest|https://github.com/apache/shardingsphere/blob/master/shardingsphere-test/shardingsphere-parser-test/src/main/java/org/apache/shardingsphere/test/sql/parser/parameterized/engine/SQLParserParameterizedTest.java]
and
[UnsupportedSQLParserParameterizedTest|https://github.com/apache/shardingsphere/blob/master/shardingsphere-test/shardingsphere-parser-test/src/main/java/org/apache/shardingsphere/test/sql/parser/parameterized/engine/UnsupportedSQLParserParameterizedTest.java]
to make sure no exceptions.
{*}Notice{*}, these issues can be a good example.
[support alter foreign table for
pg/og|https://github.com/apache/shardingsphere/pull/14944]
[support alter materialized view for
pg/og.|https://github.com/apache/shardingsphere/pull/15331]
h2. Relevant Skills
1. Master JAVA language
2. Have a basic understanding of Antlr g4 file
3. Be familiar with Postgres SQLs
h2. Targets files
1. Postgres SQLs g4 file:
[https://github.com/apache/shardingsphere/blob/master/shardingsphere-sql-parser/shardingsphere-sql-parser-dialect/shardingsphere-sql-parser-postgresql/src/main/antlr4/org/apache/shardingsphere/sql/parser/autogen/PostgreSQLStatement.g4]
h3. Mentor
Chuxin Chen, Committer of Apache ShardingSphere, [email protected]
Zhengqiang Duan, Committer of Apache ShardingSphere, [email protected]
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