Juan Pan created COMDEV-438:
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Summary: Apache ShardingSphere: Solve unsupported Postgres sql
about alter statement for ShardingSphere Parser
Key: COMDEV-438
URL: https://issues.apache.org/jira/browse/COMDEV-438
Project: Community Development
Issue Type: Improvement
Components: GSoC/Mentoring ideas
Reporter: Juan Pan
Apache ShardingSphere
Apache ShardingSphere is a distributed database middleware ecosystem, including
2 independent products, ShardingSphere JDBC and ShardingSphere Proxy presently.
They all provide functions of data sharding, distributed transaction, and
database orchestration.
{*}Page{*}:
[https://shardingsphere.apache.org|https://shardingsphere.apache.org/]
{*}Github{*}: [https://github.com/apache/shardingsphere]
h3.
h3. 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/
h3. 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]
. * ALTER OPERATOR
* ALTER POLICY
* ALTER PUBLICATION
* ALTER ROUTINE
* ALTER RULE
* ALTER SCHEMA
* ALTER SEQUENCE
* ALTER SERVER
* ALTER STATISTICS
* ALTER SUBSCRIPTION
* ALTER TABLE
* ALTER TEXT SEARCH
* ALTER TRIGGER
* ALTER TYPE
* ALTER VIEW
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]
h3. Relevant Skills
1. Master JAVA language
2. Have a basic understanding of Antlr g4 file
3. Be familiar with Postgres SQLs
h3. 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
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