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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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package org.apache.lens.cube.parse;
import java.util.Map;
import java.util.Set;
import org.apache.lens.cube.error.LensCubeErrorCode;
import org.apache.lens.cube.metadata.CubeInterface;
import org.apache.lens.cube.metadata.Dimension;
import org.apache.lens.server.api.error.LensException;
import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.hive.ql.parse.ASTNode;
import org.apache.hadoop.hive.ql.parse.HiveParser;
import org.antlr.runtime.CommonToken;
/**
* Finds queried column to table alias. Finds queried dim attributes and queried measures.
*
* Does queried field validation wrt derived cubes, if all fields of queried cube cannot be queried together.
*
* Replaces all the columns in all expressions with tablealias.column
*/
class AliasReplacer implements ContextRewriter {
@Override
public void rewriteContext(CubeQueryContext cubeql) throws LensException {
Map colToTableAlias = cubeql.getColToTableAlias();
extractTabAliasForCol(cubeql);
// Resolve aliases in all queried phrases
for (QueriedPhraseContext qur : cubeql.getQueriedPhrases()) {
extractTabAliasForCol(colToTableAlias, qur);
}
findExpressionsAndMeasures(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);
}
/**
* Figure out queried dim attributes and measures from the cube query context
* @param cubeql
* @throws LensException
*/
private void findExpressionsAndMeasures(CubeQueryContext cubeql) throws LensException {
CubeInterface cube = cubeql.getCube();
if (cube != null) {
String cubeAlias = cubeql.getAliasForTableName(cube.getName());
for (QueriedPhraseContext qur : cubeql.getQueriedPhrases()) {
Set cubeColsQueried = qur.getColumnsQueried(cubeAlias);
if (cubeColsQueried != null && !cubeColsQueried.isEmpty()) {
for (String col : cubeColsQueried) {
if (cube.getMeasureNames().contains(col)) {
qur.addQueriedMsr(col);
} else if (cube.getDimAttributeNames().contains(col)) {
qur.addQueriedDimAttr(col);
} else if (cube.getExpressionNames().contains(col)) {
qur.addQueriedExprColumn(col);
}
}
}
cubeql.addQueriedMsrs(qur.getQueriedMsrs());
cubeql.addQueriedExprs(qur.getQueriedExprColumns());
}
}
}
private void extractTabAliasForCol(CubeQueryContext cubeql) throws LensException {
extractTabAliasForCol(cubeql, cubeql);
}
static void extractTabAliasForCol(CubeQueryContext cubeql, TrackQueriedColumns tqc) throws LensException {
Map colToTableAlias = cubeql.getColToTableAlias();
Set columns = tqc.getTblAliasToColumns().get(CubeQueryContext.DEFAULT_TABLE);
if (columns == null) {
return;
}
for (String col : columns) {
boolean inCube = false;
if (cubeql.getCube() != null) {
Set cols = cubeql.getCube().getAllFieldNames();
if (cols.contains(col.toLowerCase())) {
String cubeAlias = cubeql.getAliasForTableName(cubeql.getCube().getName());
colToTableAlias.put(col.toLowerCase(), cubeAlias);
tqc.addColumnsQueried(cubeAlias, col.toLowerCase());
inCube = true;
}
}
for (Dimension dim : cubeql.getDimensions()) {
if (dim.getAllFieldNames().contains(col.toLowerCase())) {
if (!inCube) {
String prevDim = colToTableAlias.get(col.toLowerCase());
if (prevDim != null && !prevDim.equals(dim.getName())) {
throw new LensException(LensCubeErrorCode.AMBIGOUS_DIM_COLUMN.getLensErrorInfo(),
col, prevDim, dim.getName());
}
String dimAlias = cubeql.getAliasForTableName(dim.getName());
colToTableAlias.put(col.toLowerCase(), dimAlias);
tqc.addColumnsQueried(dimAlias, col.toLowerCase());
} else {
// throw error because column is in both cube and dimension table
throw new LensException(LensCubeErrorCode.AMBIGOUS_CUBE_COLUMN.getLensErrorInfo(), col,
cubeql.getCube().getName(), dim.getName());
}
}
}
if (colToTableAlias.get(col.toLowerCase()) == null) {
throw new LensException(LensCubeErrorCode.COLUMN_NOT_FOUND.getLensErrorInfo(), col);
}
}
}
private static void extractTabAliasForCol(Map colToTableAlias, TrackQueriedColumns tqc)
throws LensException {
Set columns = tqc.getTblAliasToColumns().get(CubeQueryContext.DEFAULT_TABLE);
if (columns == null) {
return;
}
for (String col : columns) {
tqc.addColumnsQueried(colToTableAlias.get(col.toLowerCase()), col.toLowerCase());
if (colToTableAlias.get(col.toLowerCase()) == null) {
throw new LensException(LensCubeErrorCode.COLUMN_NOT_FOUND.getLensErrorInfo(), col);
}
}
}
static ASTNode replaceAliases(ASTNode node, int nodePos, Map 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;
}
}
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