static ASTNode replaceAliases(ASTNode node, int nodePos, Map<String, String> colToTableAlias) {
if (node == null) {
return node;
}
int nodeType = node.getToken().getType();
if (nodeType == HiveParser.TOK_TABLE_OR_COL || nodeType == HiveParser.DOT) {
String colName = HQLParser.getColName(node);
String newAlias = colToTableAlias.get(colName.toLowerCase());
if (StringUtils.isBlank(newAlias)) {
return node;
}
if (nodeType == HiveParser.DOT) {
// No need to create a new node, just replace the table name ident
ASTNode aliasNode = (ASTNode) node.getChild(0);
ASTNode newAliasIdent = new ASTNode(new CommonToken(HiveParser.Identifier, newAlias));
aliasNode.setChild(0, newAliasIdent);
} else {
// Just a column ref, we need to make it alias.col
// '.' will become the parent node
ASTNode dot = new ASTNode(new CommonToken(HiveParser.DOT, "."));
ASTNode aliasIdentNode = new ASTNode(new CommonToken(HiveParser.Identifier, newAlias));
ASTNode tabRefNode =
new ASTNode(new CommonToken(HiveParser.TOK_TABLE_OR_COL, "TOK_TABLE_OR_COL"));
tabRefNode.addChild(aliasIdentNode);
dot.addChild(tabRefNode);
ASTNode colIdentNode = new ASTNode(new CommonToken(HiveParser.Identifier, colName));
dot.addChild(colIdentNode);
ASTNode parent = (ASTNode) node.getParent();
if (parent != null) {
parent.setChild(nodePos, dot);
} else {
return dot;
}
}
} else {
// recurse down
for (int i = 0; i < node.getChildCount(); i++) {
ASTNode child = (ASTNode) node.getChild(i);
replaceAliases(child, i, colToTableAlias);
}
}
return node;
}
@Override
public void rewriteContext(CubeQueryContext cubeql) throws LensException {
Map<String, String> colToTableAlias = cubeql.getColToTableAlias();
extractTabAliasForCol(cubeql);
findDimAttributesAndMeasures(cubeql);
if (colToTableAlias.isEmpty()) {
return;
}
// Rewrite the all the columns in the query with table alias prefixed.
// If col1 of table tab1 is accessed, it would be changed as tab1.col1.
// If tab1 is already aliased say with t1, col1 is changed as t1.col1
// replace the columns in select, groupby, having, orderby by
// prepending the table alias to the col
// sample select trees
// 1: (TOK_SELECT (TOK_SELEXPR (TOK_TABLE_OR_COL key))
// (TOK_SELEXPR (TOK_FUNCTION count (TOK_TABLE_OR_COL value))))
// 2: (TOK_SELECT (TOK_SELEXPR (. (TOK_TABLE_OR_COL src) key))
// (TOK_SELEXPR (TOK_FUNCTION count (. (TOK_TABLE_OR_COL src) value))))
// 3: (TOK_SELECT (TOK_SELEXPR (. (TOK_TABLE_OR_COL src) key) srckey))))
replaceAliases(cubeql.getSelectAST(), 0, colToTableAlias);
replaceAliases(cubeql.getHavingAST(), 0, colToTableAlias);
replaceAliases(cubeql.getOrderByAST(), 0, colToTableAlias);
replaceAliases(cubeql.getGroupByAST(), 0, colToTableAlias);
replaceAliases(cubeql.getWhereAST(), 0, colToTableAlias);
replaceAliases(cubeql.getJoinAST(), 0, colToTableAlias);
// Update the aggregate expression set
AggregateResolver.updateAggregates(cubeql.getSelectAST(), cubeql);
AggregateResolver.updateAggregates(cubeql.getHavingAST(), cubeql);
// Update alias map as well
updateAliasMap(cubeql.getSelectAST(), cubeql);
}
public void replaceAliasInAST(CubeQueryContext cubeql) throws SemanticException {
AliasReplacer.extractTabAliasForCol(cubeql, this);
AliasReplacer.replaceAliases(finalAST, 0, cubeql.getColToTableAlias());
}
