[jira] [Updated] (COMDEV-468) Apache ShardingSphere: Solve unsupported Postgres sql about statements that start with 'd', 'e', 'f', 'i' for ShardingSphere Parser

["Chuxin Chen (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COMDEV-468?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chuxin Chen updated COMDEV-468:
-------------------------------
    difficulty-level:   (was: Easy)

> Apache ShardingSphere: Solve unsupported Postgres sql about statements that start with 'd', 'e', 'f', 'i' for ShardingSphere Parser
> -----------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: COMDEV-468
>                 URL: https://issues.apache.org/jira/browse/COMDEV-468
>             Project: Community Development
>          Issue Type: Improvement
>          Components: GSoC/Mentoring ideas
>            Reporter: Chuxin Chen
>            Priority: Major
>              Labels: Mentor, ShardingSphere, gsoc2022
>
> 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, tuichenchuxin@apache.org
> Zhengqiang Duan, Committer of Apache ShardingSphere, duanzhengqiang@apache.org



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