Parse engine rejects CURRENT_USER in 4.0.0

[encodeering]

Bug Report

Which version of ShardingSphere did you use?

4.0.0

Which project did you use? Sharding-JDBC or Sharding-Proxy?

Sharding-JDBC

Expected behavior

Update from 3.1.0 to 4.0.0 would not change the parser rules.

Actual behavior

Integration tests fail because flyway can't perform a migration when executing select CURRENT_USER

Reason analyze (If you can)

org.postgresql:postgresql:42.2.6
org.flywaydb:flyway-core:5.2.4
org.testcontainers:postgresql:1.12.0

sql = "SELECT CURRENT_USER"
parseEngine = {SQLParseEngine@4966} 
 databaseTypeName = "PostgreSQL"

line 1:7 mismatched input 'CURRENT_USER' expecting {'U', 'u', '!', '~', '+', '-', '*', '(', '{', '?', INSERT, UPDATE, DELETE, ALTER, DROP, TRUNCATE, SCHEMA, REVOKE, ADD, SET, INDEX, KEY, FUNCTION, TRIGGER, PROCEDURE, DISTINCT, CASE, CAST, IF, NOT, NULL, TRUE, FALSE, EXISTS, ALL, BEGIN, COMMIT, ROLLBACK, SAVEPOINT, BOOLEAN, CHAR, INTERVAL, TIME, TIMESTAMP, LOCALTIME, LOCALTIMESTAMP, YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, MAX, MIN, SUM, COUNT, AVG, CURRENT, ENABLE, DISABLE, INSTANCE, PRESERVE, DEFINER, SQL, CASCADED, LOCAL, CLOSE, OPEN, NEXT, NAME, NAMES, INTEGER, REAL, DECIMAL, TYPE, ADMIN, BINARY, ESCAPE, EXCLUDE, PARTITION, ROW, UNKNOWN, ALWAYS, CASCADE, GENERATED, ISOLATION, LEVEL, OPTION, PRIVILEGES, READ, ROLE, ROWS, START, TRANSACTION, ACTION, CACHE, CHARACTERISTICS, CLUSTER, COMMENTS, CONSTRAINTS, CURRENT_TIMESTAMP, CYCLE, DATA, DATABASE, DEFAULTS, DEFERRED, DEPENDS, DOMAIN, EXCLUDING, EXECUTE, EXTENDED, EXTENSION, EXTERNAL, EXTRACT, FILTER, FIRST, FOLLOWING, FORCE, GLOBAL, IDENTITY, IMMEDIATE, INCLUDING, INCREMENT, INDEXES, INHERIT, INHERITS, INCLUDE, LANGUAGE, LARGE, LAST, LOGGED, MAIN, MATCH, MAXVALUE, MINVALUE, NOTHING, NULLS, OBJECT, OIDS, OVER, OWNED, OWNER, PARTIAL, PLAIN, PRECEDING, RANGE, RENAME, REPLICA, RESET, RESTART, RESTRICT, ROUTINE, RULE, SECURITY, SEQUENCE, SESSION, SHOW, SIMPLE, STATISTICS, STORAGE, TABLESPACE, TEMP, TEMPORARY, UNBOUNDED, UNLOGGED, USAGE, VALID, VALIDATE, WITHIN, WITHOUT, ZONE, OF, GROUPS, RECURSIVE, IDENTIFIER_, STRING_, NUMBER_, HEX_DIGIT_, BIT_NUM_}

java.lang.IllegalStateException
	at com.google.common.base.Preconditions.checkState(Preconditions.java:429)
	at org.apache.shardingsphere.sql.parser.core.extractor.util.ExtractorUtils.getFirstChildNode(ExtractorUtils.java:48)
	at org.apache.shardingsphere.sql.parser.core.extractor.impl.dml.select.SelectItemsExtractor.extract(SelectItemsExtractor.java:54)
	at org.apache.shardingsphere.sql.parser.core.extractor.SQLSegmentsExtractorEngine.extract(SQLSegmentsExtractorEngine.java:47)
	at org.apache.shardingsphere.sql.parser.core.SQLParseKernel.parse(SQLParseKernel.java:59)
	at org.apache.shardingsphere.sql.parser.SQLParseEngine.parse0(SQLParseEngine.java:70)
	at org.apache.shardingsphere.sql.parser.SQLParseEngine.parse(SQLParseEngine.java:52)
	at org.apache.shardingsphere.core.route.router.masterslave.MasterSlaveRouter.route(MasterSlaveRouter.java:56)
	at org.apache.shardingsphere.shardingjdbc.jdbc.core.statement.MasterSlavePreparedStatement.<init>(MasterSlavePreparedStatement.java:68)
	at org.apache.shardingsphere.shardingjdbc.jdbc.core.statement.MasterSlavePreparedStatement.<init>(MasterSlavePreparedStatement.java:53)
	at org.apache.shardingsphere.shardingjdbc.jdbc.core.connection.MasterSlaveConnection.prepareStatement(MasterSlaveConnection.java:76)
	at org.flywaydb.core.internal.jdbc.JdbcTemplate.prepareStatement(JdbcTemplate.java:333)
	at org.flywaydb.core.internal.jdbc.JdbcTemplate.queryForString(JdbcTemplate.java:190)
	at org.flywaydb.core.internal.database.postgresql.PostgreSQLConnection.<init>(PostgreSQLConnection.java:48)
	at org.flywaydb.core.internal.database.postgresql.PostgreSQLDatabase.getConnection(PostgreSQLDatabase.java:56)
	at org.flywaydb.core.internal.database.postgresql.PostgreSQLDatabase.getConnection(PostgreSQLDatabase.java:31)
	at org.flywaydb.core.internal.database.base.Database.getMainConnection(Database.java:366)
	at org.flywaydb.core.Flyway.prepareSchemas(Flyway.java:1773)
	at org.flywaydb.core.Flyway.execute(Flyway.java:1678)
	at org.flywaydb.core.Flyway.migrate(Flyway.java:1356)

Steps to reproduce the behavior, such as: SQL to execute, sharding rule configuration, when exception occur etc.

Should be reproducible if the mentioned statement is executed with the PostgreSQL SQLParseEngine

Example codes for reproduce this issue (such as a github link).

[SteNicholas]

@encodeering 4.0.0 PostgreSQLParser doesn't support SELECT CURRENT_USER, I would like to add the keyword to simpleExpr.

[encodeering]

Hi @SteNicholas @terrymanu, thanks for the fast reply.

Could you please point me to a maven repository where I could test the current snapshot?
Would it be possible to have this change also part of a 4.0.x release if the schedule for 5.x is not yet known?

[SteNicholas]

@encodeering Hi encodeering, you should clone the shardingsphere to local, checkout the dev branch, and execute mvn clean install -DskipTests -Dfast to compile. Then you could use the compiled version for you application. 5.X version doesn't release. If you don't have any question, please close this issue. Thanks.

[encodeering]

Okay, will do that, thanks for the command line 👍