/*
* Builds results for a DESCRIBE <table> command. This consists of the column
* definition for each column in the table.
*/
private static TDescribeTableResult describeTableMinimal(Table table) {
TDescribeTableResult descResult = new TDescribeTableResult();
descResult.results = Lists.newArrayList();
// Get description of all the table's columns (includes partition columns).
for (Column column : table.getColumnsInHiveOrder()) {
TColumnValue colNameCol = new TColumnValue();
colNameCol.setString_val(column.getName());
TColumnValue dataTypeCol = new TColumnValue();
dataTypeCol.setString_val(column.getType().toString().toLowerCase());
TColumnValue commentCol = new TColumnValue();
commentCol.setString_val(column.getComment() != null ? column.getComment() : "");
descResult.results.add(
new TResultRow(Lists.newArrayList(colNameCol, dataTypeCol, commentCol)));
}
return descResult;
}
/**
* Performs three final parts of the analysis: 1. Checks type compatibility between all
* expressions and their targets
*
* <p>2. Populates partitionKeyExprs with type-compatible expressions, in Hive partition-column
* order, for all partition columns
*
* <p>3. Populates resultExprs_ with type-compatible expressions, in Hive column order, for all
* expressions in the select-list. Unmentioned columns are assigned NULL literal expressions.
*
* <p>If necessary, adds casts to the expressions to make them compatible with the type of the
* corresponding column.
*
* @throws AnalysisException If an expression is not compatible with its target column
*/
private void prepareExpressions(
List<Column> selectExprTargetColumns,
List<Expr> selectListExprs,
Table tbl,
Analyzer analyzer)
throws AnalysisException {
// Temporary lists of partition key exprs and names in an arbitrary order.
List<Expr> tmpPartitionKeyExprs = new ArrayList<Expr>();
List<String> tmpPartitionKeyNames = new ArrayList<String>();
int numClusteringCols = (tbl instanceof HBaseTable) ? 0 : tbl.getNumClusteringCols();
// Check dynamic partition columns for type compatibility.
for (int i = 0; i < selectListExprs.size(); ++i) {
Column targetColumn = selectExprTargetColumns.get(i);
Expr compatibleExpr = checkTypeCompatibility(targetColumn, selectListExprs.get(i));
if (targetColumn.getPosition() < numClusteringCols) {
// This is a dynamic clustering column
tmpPartitionKeyExprs.add(compatibleExpr);
tmpPartitionKeyNames.add(targetColumn.getName());
}
selectListExprs.set(i, compatibleExpr);
}
// Check static partition columns, dynamic entries in partitionKeyValues will already
// be in selectExprTargetColumns and therefore are ignored in this loop
if (partitionKeyValues_ != null) {
for (PartitionKeyValue pkv : partitionKeyValues_) {
if (pkv.isStatic()) {
// tableColumns is guaranteed to exist after the earlier analysis checks
Column tableColumn = table_.getColumn(pkv.getColName());
Expr compatibleExpr = checkTypeCompatibility(tableColumn, pkv.getValue());
tmpPartitionKeyExprs.add(compatibleExpr);
tmpPartitionKeyNames.add(pkv.getColName());
}
}
}
// Reorder the partition key exprs and names to be consistent with the target table
// declaration. We need those exprs in the original order to create the corresponding
// Hdfs folder structure correctly.
for (Column c : table_.getColumns()) {
for (int j = 0; j < tmpPartitionKeyNames.size(); ++j) {
if (c.getName().equals(tmpPartitionKeyNames.get(j))) {
partitionKeyExprs_.add(tmpPartitionKeyExprs.get(j));
break;
}
}
}
Preconditions.checkState(partitionKeyExprs_.size() == numClusteringCols);
// Make sure we have stats for partitionKeyExprs
for (Expr expr : partitionKeyExprs_) {
expr.analyze(analyzer);
}
// Finally, 'undo' the permutation so that the selectListExprs are in Hive column
// order, and add NULL expressions to all missing columns.
for (Column tblColumn : table_.getColumnsInHiveOrder()) {
boolean matchFound = false;
for (int i = 0; i < selectListExprs.size(); ++i) {
if (selectExprTargetColumns.get(i).getName().equals(tblColumn.getName())) {
resultExprs_.add(selectListExprs.get(i));
matchFound = true;
break;
}
}
// If no match is found, either the column is a clustering column with a static
// value, or it was unmentioned and therefore should have a NULL select-list
// expression.
if (!matchFound) {
if (tblColumn.getPosition() >= numClusteringCols) {
// Unmentioned non-clustering columns get NULL literals with the appropriate
// target type because Parquet cannot handle NULL_TYPE (IMPALA-617).
resultExprs_.add(NullLiteral.create(tblColumn.getType()));
}
}
}
// TODO: Check that HBase row-key columns are not NULL? See IMPALA-406
if (needsGeneratedQueryStatement_) {
// Build a query statement that returns NULL for every column
List<SelectListItem> selectListItems = Lists.newArrayList();
for (Expr e : resultExprs_) {
selectListItems.add(new SelectListItem(e, null));
}
SelectList selectList = new SelectList(selectListItems);
queryStmt_ = new SelectStmt(selectList, null, null, null, null, null, null);
queryStmt_.analyze(analyzer);
}
}