Examples with FromClause org.apache.asterix.lang.sqlpp.clause.FromClause used on opensource projects

Example 1 with FromClause

use of org.apache.asterix.lang.sqlpp.clause.FromClause in project asterixdb by apache.

the class SqlppGroupBySugarVisitor method wrapAggregationArgument.

private Expression wrapAggregationArgument(Expression argExpr) throws CompilationException {
    Expression expr = argExpr;
    Set<VariableExpr> freeVars = SqlppRewriteUtil.getFreeVariable(expr);
    VariableExpr fromBindingVar = new VariableExpr(context.newVariable());
    FromTerm fromTerm = new FromTerm(groupVar, fromBindingVar, null, null);
    FromClause fromClause = new FromClause(Collections.singletonList(fromTerm));
    // Maps field variable expressions to field accesses.
    Map<Expression, Expression> varExprMap = new HashMap<>();
    for (VariableExpr usedVar : freeVars) {
        // Reference to a field in the group variable.
        if (fieldVars.contains(usedVar)) {
            // Rewrites to a reference to a field in the group variable.
            varExprMap.put(usedVar, new FieldAccessor(fromBindingVar, SqlppVariableUtil.toUserDefinedVariableName(usedVar.getVar())));
        }
    }
    // Select clause.
    SelectElement selectElement = new SelectElement(SqlppRewriteUtil.substituteExpression(expr, varExprMap, context));
    SelectClause selectClause = new SelectClause(selectElement, null, false);
    // Construct the select expression.
    SelectBlock selectBlock = new SelectBlock(selectClause, fromClause, null, null, null, null, null);
    SelectSetOperation selectSetOperation = new SelectSetOperation(new SetOperationInput(selectBlock, null), null);
    return new SelectExpression(null, selectSetOperation, null, null, true);
}

Example 2 with FromClause

use of org.apache.asterix.lang.sqlpp.clause.FromClause in project asterixdb by apache.

the class SqlppGroupByVisitor method visit.

@Override
public Expression visit(GroupbyClause gc, ILangExpression arg) throws CompilationException {
    // Puts all FROM binding variables into withVarList.
    FromClause fromClause = (FromClause) arg;
    Collection<VariableExpr> fromBindingVars = fromClause == null ? new ArrayList<>() : SqlppVariableUtil.getBindingVariables(fromClause);
    Map<Expression, VariableExpr> withVarMap = new HashMap<>();
    for (VariableExpr fromBindingVar : fromBindingVars) {
        VariableExpr varExpr = new VariableExpr();
        varExpr.setIsNewVar(false);
        varExpr.setVar(fromBindingVar.getVar());
        VariableExpr newVarExpr = (VariableExpr) SqlppRewriteUtil.deepCopy(varExpr);
        withVarMap.put(varExpr, newVarExpr);
    }
    // Sets the field list for the group variable.
    List<Pair<Expression, Identifier>> groupFieldList = new ArrayList<>();
    if (!gc.hasGroupFieldList()) {
        for (VariableExpr varExpr : fromBindingVars) {
            Pair<Expression, Identifier> varIdPair = new Pair<>(new VariableExpr(varExpr.getVar()), SqlppVariableUtil.toUserDefinedVariableName(varExpr.getVar()));
            groupFieldList.add(varIdPair);
        }
        gc.setGroupFieldList(groupFieldList);
    } else {
        for (Pair<Expression, Identifier> groupField : gc.getGroupFieldList()) {
            Expression newFieldExpr = groupField.first.accept(this, arg);
            groupFieldList.add(new Pair<>(newFieldExpr, groupField.second));
            // Adds a field binding variable into withVarList.
            VariableExpr bindingVar = new VariableExpr(new VarIdentifier(SqlppVariableUtil.toInternalVariableName(groupField.second.getValue())));
            withVarMap.put(newFieldExpr, bindingVar);
        }
    }
    gc.setGroupFieldList(groupFieldList);
    // Sets the group variable.
    if (!gc.hasGroupVar()) {
        VariableExpr groupVar = new VariableExpr(context.newVariable());
        gc.setGroupVar(groupVar);
    }
    // Adds the group variable into the "with" (i.e., re-binding) variable list.
    VariableExpr gbyVarRef = new VariableExpr(gc.getGroupVar().getVar());
    gbyVarRef.setIsNewVar(false);
    withVarMap.put(gbyVarRef, (VariableExpr) SqlppRewriteUtil.deepCopy(gbyVarRef));
    gc.setWithVarMap(withVarMap);
    // Call super.visit(...) to scope variables.
    return super.visit(gc, arg);
}

Example 3 with FromClause

use of org.apache.asterix.lang.sqlpp.clause.FromClause in project asterixdb by apache.

the class SqlppGroupByVisitor method visit.

@Override
public Expression visit(SelectBlock selectBlock, ILangExpression arg) throws CompilationException {
    // Traverses the select block in the order of "from", "let"s, "where",
    // "group by", "let"s, "having" and "select".
    FromClause fromClause = selectBlock.getFromClause();
    if (selectBlock.hasFromClause()) {
        fromClause.accept(this, arg);
    }
    if (selectBlock.hasLetClauses()) {
        List<LetClause> letList = selectBlock.getLetList();
        for (LetClause letClause : letList) {
            letClause.accept(this, arg);
        }
    }
    if (selectBlock.hasWhereClause()) {
        selectBlock.getWhereClause().accept(this, arg);
    }
    if (selectBlock.hasGroupbyClause()) {
        GroupbyClause groupbyClause = selectBlock.getGroupbyClause();
        groupbyClause.accept(this, fromClause);
        Collection<VariableExpr> visibleVarsInCurrentScope = SqlppVariableUtil.getBindingVariables(groupbyClause);
        VariableExpr groupVar = groupbyClause.getGroupVar();
        Set<VariableExpr> groupFieldVars = getGroupFieldVariables(groupbyClause);
        Collection<VariableExpr> freeVariablesInGbyLets = new HashSet<>();
        if (selectBlock.hasLetClausesAfterGroupby()) {
            List<LetClause> letListAfterGby = selectBlock.getLetListAfterGroupby();
            for (LetClause letClauseAfterGby : letListAfterGby) {
                letClauseAfterGby.accept(this, arg);
                // Rewrites each let clause after the group-by.
                SqlppRewriteUtil.rewriteExpressionUsingGroupVariable(groupVar, groupFieldVars, letClauseAfterGby, context);
                Collection<VariableExpr> freeVariablesInLet = SqlppVariableUtil.getFreeVariables(letClauseAfterGby.getBindingExpr());
                freeVariablesInLet.removeAll(visibleVarsInCurrentScope);
                freeVariablesInGbyLets.addAll(freeVariablesInLet);
                visibleVarsInCurrentScope.add(letClauseAfterGby.getVarExpr());
            }
        }
        Collection<VariableExpr> freeVariables = new HashSet<>();
        if (selectBlock.hasHavingClause()) {
            // Rewrites the having clause.
            HavingClause havingClause = selectBlock.getHavingClause();
            havingClause.accept(this, arg);
            SqlppRewriteUtil.rewriteExpressionUsingGroupVariable(groupVar, groupFieldVars, havingClause, context);
            freeVariables.addAll(SqlppVariableUtil.getFreeVariables(havingClause));
        }
        SelectExpression parentSelectExpression = (SelectExpression) arg;
        // We cannot rewrite ORDER BY and LIMIT if it's a SET operation query.
        if (!parentSelectExpression.getSelectSetOperation().hasRightInputs()) {
            if (parentSelectExpression.hasOrderby()) {
                // Rewrites the ORDER BY clause.
                OrderbyClause orderbyClause = parentSelectExpression.getOrderbyClause();
                orderbyClause.accept(this, arg);
                SqlppRewriteUtil.rewriteExpressionUsingGroupVariable(groupVar, groupFieldVars, orderbyClause, context);
                freeVariables.addAll(SqlppVariableUtil.getFreeVariables(orderbyClause));
            }
            if (parentSelectExpression.hasLimit()) {
                // Rewrites the LIMIT clause.
                LimitClause limitClause = parentSelectExpression.getLimitClause();
                limitClause.accept(this, arg);
                SqlppRewriteUtil.rewriteExpressionUsingGroupVariable(groupVar, groupFieldVars, limitClause, context);
                freeVariables.addAll(SqlppVariableUtil.getFreeVariables(limitClause));
            }
        }
        // Visits the select clause.
        SelectClause selectClause = selectBlock.getSelectClause();
        selectClause.accept(this, arg);
        // Rewrites the select clause.
        SqlppRewriteUtil.rewriteExpressionUsingGroupVariable(groupVar, groupFieldVars, selectClause, context);
        freeVariables.addAll(SqlppVariableUtil.getFreeVariables(selectClause));
        freeVariables.removeAll(visibleVarsInCurrentScope);
        // Gets the final free variables.
        freeVariables.addAll(freeVariablesInGbyLets);
        // Gets outer scope variables.
        Collection<VariableExpr> decorVars = SqlppVariableUtil.getLiveVariables(scopeChecker.getCurrentScope(), true);
        decorVars.removeAll(visibleVarsInCurrentScope);
        // Need path resolution or not?
        boolean needResolution = !decorVars.containsAll(freeVariables);
        // Otherwise, we only need to retain used free variables.
        if (needResolution) {
            // Tracks used variables, including WITH variables.
            decorVars.retainAll(freeVariables);
            // Adds all non-WITH outer scope variables, for path resolution.
            Collection<VariableExpr> visibleOuterScopeNonWithVars = SqlppVariableUtil.getLiveVariables(scopeChecker.getCurrentScope(), false);
            visibleOuterScopeNonWithVars.removeAll(visibleVarsInCurrentScope);
            decorVars.addAll(visibleOuterScopeNonWithVars);
        } else {
            // Only retains used free variables.
            decorVars.retainAll(freeVariables);
        }
        if (!decorVars.isEmpty()) {
            // Adds used WITH variables.
            Collection<VariableExpr> visibleOuterScopeNonWithVars = SqlppVariableUtil.getLiveVariables(scopeChecker.getCurrentScope(), false);
            visibleOuterScopeNonWithVars.retainAll(freeVariables);
            decorVars.addAll(visibleOuterScopeNonWithVars);
            // Adds necessary decoration variables for the GROUP BY.
            // NOTE: we need to include WITH binding variables so as they can be evaluated before
            // the GROUP BY instead of being inlined as part of nested pipepline. The current optimzier
            // is not able to optimize the latter case. The following query is such an example:
            // asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/dapd/q2-11
            List<GbyVariableExpressionPair> decorList = new ArrayList<>();
            for (VariableExpr var : decorVars) {
                decorList.add(new GbyVariableExpressionPair((VariableExpr) SqlppRewriteUtil.deepCopy(var), (Expression) SqlppRewriteUtil.deepCopy(var)));
            }
            groupbyClause.getDecorPairList().addAll(decorList);
        }
    } else {
        selectBlock.getSelectClause().accept(this, arg);
    }
    return null;
}

Example 4 with FromClause

use of org.apache.asterix.lang.sqlpp.clause.FromClause in project asterixdb by apache.

the class SetOperationVisitor method visit.

@Override
public Expression visit(SelectExpression selectExpression, ILangExpression arg) throws CompilationException {
    // Recursively visit nested select expressions.
    SelectSetOperation selectSetOperation = selectExpression.getSelectSetOperation();
    if (!selectSetOperation.hasRightInputs() || !(selectExpression.hasOrderby() || selectExpression.hasLimit())) {
        return super.visit(selectExpression, arg);
    }
    OrderbyClause orderBy = selectExpression.getOrderbyClause();
    LimitClause limit = selectExpression.getLimitClause();
    // Wraps the set operation part with a subquery.
    SelectExpression nestedSelectExpression = new SelectExpression(null, selectSetOperation, null, null, true);
    // Binding variable for the subquery.
    VariableExpr newBindingVar = new VariableExpr(context.newVariable());
    FromTerm newFromTerm = new FromTerm(nestedSelectExpression, newBindingVar, null, null);
    FromClause newFromClause = new FromClause(new ArrayList<>(Collections.singletonList(newFromTerm)));
    SelectClause selectClause = new SelectClause(new SelectElement(newBindingVar), null, false);
    SelectBlock selectBlock = new SelectBlock(selectClause, newFromClause, null, null, null, null, null);
    SelectSetOperation newSelectSetOperation = new SelectSetOperation(new SetOperationInput(selectBlock, null), null);
    // Puts together the generated select-from-where query and order by/limit.
    SelectExpression newSelectExpression = new SelectExpression(selectExpression.getLetList(), newSelectSetOperation, orderBy, limit, selectExpression.isSubquery());
    return super.visit(newSelectExpression, arg);
}

Example 5 with FromClause

use of org.apache.asterix.lang.sqlpp.clause.FromClause in project asterixdb by apache.

the class SqlppCloneAndSubstituteVariablesVisitor method visit.

@Override
public Pair<ILangExpression, VariableSubstitutionEnvironment> visit(FromClause fromClause, VariableSubstitutionEnvironment env) throws CompilationException {
    VariableSubstitutionEnvironment currentEnv = new VariableSubstitutionEnvironment(env);
    List<FromTerm> newFromTerms = new ArrayList<>();
    for (FromTerm fromTerm : fromClause.getFromTerms()) {
        Pair<ILangExpression, VariableSubstitutionEnvironment> p = fromTerm.accept(this, currentEnv);
        newFromTerms.add((FromTerm) p.first);
        // A right from term could be correlated from a left from term,
        // therefore we propagate the substitution environment.
        currentEnv = p.second;
    }
    return new Pair<>(new FromClause(newFromTerms), currentEnv);
}