/**
* Get a list of indexes which can be used for rewrite.
*
* @return
* @throws SemanticException
*/
private Map<Table, List<Index>> getIndexesForRewrite() throws SemanticException {
List<String> supportedIndexes = new ArrayList<String>();
supportedIndexes.add(AggregateIndexHandler.class.getName());
// query the metastore to know what columns we have indexed
Collection<Table> topTables = parseContext.getTopToTable().values();
Map<Table, List<Index>> indexes = new HashMap<Table, List<Index>>();
for (Table tbl : topTables) {
List<Index> tblIndexes = IndexUtils.getIndexes(tbl, supportedIndexes);
if (tblIndexes.size() > 0) {
indexes.put(tbl, tblIndexes);
}
}
return indexes;
}
/**
* This method checks if the index is built on all partitions of the base table. If not, then the
* method returns false as we do not apply optimization for this case.
*
* @param tableScan
* @param indexes
* @return
* @throws SemanticException
*/
private boolean checkIfIndexBuiltOnAllTablePartitions(
TableScanOperator tableScan, Map<Table, List<Index>> indexes) throws SemanticException {
// check if we have indexes on all partitions in this table scan
Set<Partition> queryPartitions;
try {
queryPartitions = IndexUtils.checkPartitionsCoveredByIndex(tableScan, parseContext, indexes);
if (queryPartitions == null) { // partitions not covered
return false;
}
} catch (HiveException e) {
LOG.error("Fatal Error: problem accessing metastore", e);
throw new SemanticException(e);
}
if (queryPartitions.size() != 0) {
return true;
}
return false;
}