org.hibernate.community.dialect.AltibaseSqlAstTranslator Maven / Gradle / Ivy

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or .
 */

package org.hibernate.community.dialect;

import java.util.List;

import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.query.sqm.ComparisonOperator;
import org.hibernate.query.sqm.FrameExclusion;
import org.hibernate.query.sqm.FrameKind;
import org.hibernate.sql.ast.SqlAstJoinType;
import org.hibernate.sql.ast.spi.AbstractSqlAstTranslator;
import org.hibernate.sql.ast.tree.Statement;
import org.hibernate.sql.ast.tree.expression.Expression;
import org.hibernate.sql.ast.tree.expression.FunctionExpression;
import org.hibernate.sql.ast.tree.expression.Literal;
import org.hibernate.sql.ast.tree.expression.Over;
import org.hibernate.sql.ast.tree.expression.QueryLiteral;
import org.hibernate.sql.ast.tree.expression.Summarization;
import org.hibernate.sql.ast.tree.from.QueryPartTableReference;
import org.hibernate.sql.ast.tree.from.TableGroupJoin;
import org.hibernate.sql.ast.tree.from.ValuesTableReference;
import org.hibernate.sql.ast.tree.predicate.BooleanExpressionPredicate;
import org.hibernate.sql.ast.tree.predicate.Predicate;
import org.hibernate.sql.ast.tree.select.QueryPart;
import org.hibernate.sql.ast.tree.select.QuerySpec;
import org.hibernate.sql.exec.spi.JdbcOperation;

/**
 * A SQL AST translator for Altibase.
 *
 * @author Geoffrey Park
 */
public class AltibaseSqlAstTranslator extends AbstractSqlAstTranslator {

	public AltibaseSqlAstTranslator(SessionFactoryImplementor sessionFactory, Statement statement) {
		super( sessionFactory, statement );
	}

	@Override
	public void visitOffsetFetchClause(QueryPart queryPart) {
		if ( !isRowNumberingCurrentQueryPart() ) {
			// Use limit because Altibase does not support fetch first rows only.
			renderCombinedLimitClause( queryPart );
		}
	}

	@Override
	protected void renderComparison(Expression lhs, ComparisonOperator operator, Expression rhs) {
		// Altibase does not support is distinct from clause. So override renderComparion() and use not exists
		renderComparisonEmulateIntersect( lhs, operator, rhs );
	}

	@Override
	public void visitOver(Over over) {
		final Expression expression = over.getExpression();
		if ( expression instanceof FunctionExpression && "row_number".equals( ( (FunctionExpression) expression ).getFunctionName() ) ) {
			if ( over.getPartitions().isEmpty() && over.getOrderList().isEmpty()
					&& over.getStartKind() == FrameKind.UNBOUNDED_PRECEDING
					&& over.getEndKind() == FrameKind.CURRENT_ROW
					&& over.getExclusion() == FrameExclusion.NO_OTHERS ) {
				// Altibase doesn't allow an empty over clause for the row_number() function,
				append( "row_number() over(order by 1)" );
				return;
			}
		}
		super.visitOver( over );
	}

	@Override
	public void visitQuerySpec(QuerySpec querySpec) {
		if ( shouldEmulateFetchClause( querySpec ) ) {
			// Altibase does not support row_with_ties
			emulateFetchOffsetWithWindowFunctions( querySpec, true );
		}
		else {
			super.visitQuerySpec( querySpec );
		}
	}

	protected boolean shouldEmulateFetchClause(QueryPart queryPart) {
		// Check if current query part is already row numbering to avoid infinite recursion
		return useOffsetFetchClause( queryPart ) && getQueryPartForRowNumbering() != queryPart
				&& getDialect().supportsWindowFunctions() && !isRowsOnlyFetchClauseType( queryPart );
	}

	protected void renderTableGroupJoin(TableGroupJoin tableGroupJoin, List tableGroupJoinCollector) {
		// Use join instead because Altibase does not support cross apply
		appendSql( WHITESPACE );
		if ( tableGroupJoin.getJoinType() != SqlAstJoinType.CROSS ) {
			// No support for cross joins, so we emulate it with an inner join and always true on condition
			appendSql( tableGroupJoin.getJoinType().getText() );
		}
		appendSql( "join " );

		final Predicate predicate;
		if ( tableGroupJoin.getPredicate() == null ) {
			predicate = new BooleanExpressionPredicate( new QueryLiteral<>( true, getBooleanType() ) );
		}
		else {
			predicate = tableGroupJoin.getPredicate();
		}
		if ( predicate != null && !predicate.isEmpty() ) {
			renderTableGroup( tableGroupJoin.getJoinedGroup(), predicate, tableGroupJoinCollector );
		}
		else {
			renderTableGroup( tableGroupJoin.getJoinedGroup(), null, tableGroupJoinCollector );
		}
	}

	@Override
	protected void renderPartitionItem(Expression expression) {
		if ( expression instanceof Literal ) {
			appendSql( "'0' || '0'" );
		}
		else if ( expression instanceof Summarization ) {
			// This could theoretically be emulated by rendering all grouping variations of the query and
			// connect them via union all but that's probably pretty inefficient and would have to happen
			// on the query spec level
			throw new UnsupportedOperationException( "Summarization is not supported by DBMS!" );
		}
		else {
			expression.accept( this );
		}
	}

	@Override
	protected void renderOffsetExpression(Expression offsetExpression) {
		// Altibase offset starts from 1
		appendSql( "1+" );
		offsetExpression.accept( this );
	}

	@Override
	public void visitValuesTableReference(ValuesTableReference tableReference) {
		emulateValuesTableReferenceColumnAliasing( tableReference );
	}

	@Override
	public void visitQueryPartTableReference(QueryPartTableReference tableReference) {
		emulateQueryPartTableReferenceColumnAliasing( tableReference );
	}

	protected String getFromDual() {
		return " from dual";
	}

	@Override
	protected String getFromDualForSelectOnly() {
		return getFromDual();
	}

	@Override
	protected boolean needsRecursiveKeywordInWithClause() {
		return false;
	}

	@Override
	protected boolean supportsRowValueConstructorSyntaxInQuantifiedPredicates() {
		return false;
	}

	@Override
	protected boolean supportsWithClauseInSubquery() {
		return false;
	}

	@Override
	protected boolean supportsSimpleQueryGrouping() {
		return false;
	}

}