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package com.shf.sql;

import com.alibaba.druid.sql.SQLUtils;

import com.alibaba.druid.sql.ast.SQLCommentHint;

import com.alibaba.druid.sql.ast.SQLObject;

import com.alibaba.druid.sql.ast.SQLStatement;

import com.alibaba.druid.sql.ast.expr.SQLPropertyExpr;

import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;

import com.alibaba.druid.sql.ast.statement.SQLJoinTableSource;

import com.alibaba.druid.sql.ast.statement.SQLSelect;

import com.alibaba.druid.sql.ast.statement.SQLSelectQuery;

import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;

import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;

import com.alibaba.druid.sql.visitor.SQLASTOutputVisitor;

import com.alibaba.druid.util.JdbcConstants;

import lombok.extern.slf4j.Slf4j;

import org.apache.commons.collections4.CollectionUtils;

import org.junit.Test;

import java.util.Collections;

import java.util.List;

/**

* description :

* Add hint by druid.

*

* @author songhaifeng

* @date 2021/10/15 9:49

*/

@Slf4j

public class HintTest {

@Test

public void hint() {

// SELECT /*+ READ_FROM_STORAGE(TIFLASH[test1.t1,test2.t2]) */ t1.a FROM test1.t t1, test2.t t2 WHERE t1.a = t2.a;

String sql = "SELECT t1.a FROM test1.t t1, test2.t t2 WHERE t1.a = t2.a ";

List<SQLStatement> statementList = SQLUtils.parseStatements(sql, JdbcConstants.MYSQL);

SQLSelectStatement sqlSelectStatement = (SQLSelectStatement) statementList.get(0);

List<SQLObject> sqlObjects = sqlSelectStatement.getChildren();

if (CollectionUtils.isNotEmpty(sqlObjects)) {

SQLObject sqlObject = sqlObjects.get(0);

if (sqlObject instanceof SQLSelect) {

SQLSelectQuery sqlSelectQuery = ((SQLSelect) sqlObject).getQuery();

SQLSelectQueryBlock sqlSelectQueryBlock = ((SQLSelectQueryBlock) sqlSelectQuery);

SQLJoinTableSource sqlJoinTableSource = (SQLJoinTableSource) sqlSelectQueryBlock.getFrom();

String leftTable = getFullAliasName((SQLExprTableSource) sqlJoinTableSource.getLeft());

String rightTable = getFullAliasName((SQLExprTableSource) sqlJoinTableSource.getRight());

SQLCommentHint sqlCommentHint = new SQLCommentHint();

sqlCommentHint.setText("+ READ_FROM_STORAGE(TIFLASH[" + leftTable + "," + rightTable + "])");

sqlSelectQueryBlock.setHint(sqlCommentHint);

sqlSelectQueryBlock.setHints(Collections.singletonList(sqlCommentHint));

}

}

log.info(sqlSelectStatement.toString());

StringBuilder out = new StringBuilder();

sqlSelectStatement.accept(new SQLASTOutputVisitor(out, true));

String newSQL = out.toString();

log.info(newSQL);

}

private String getFullAliasName(SQLExprTableSource sqlTableSource) {

String aliasName = sqlTableSource.getAlias();

SQLPropertyExpr sqlPropertyExpr = (SQLPropertyExpr) sqlTableSource.getExpr();

String database = sqlPropertyExpr.getOwnerName();

return database + "." + aliasName;

}

}