[GitHub] [hive] pvary commented on a change in pull request #2843: HIVE-25773: Column descriptors might not be deleted via direct sql

[GitBox <gi...@apache.org>]

pvary commented on a change in pull request #2843:
URL: https://github.com/apache/hive/pull/2843#discussion_r762739223



##########
File path: standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/MetaStoreDirectSql.java
##########
@@ -2818,26 +2820,24 @@ private void dropDanglingColumnDescriptors(List<Object> columnDescriptorIdList)
 
     // Drop column descriptor, if no relation left
     queryText =
-        "SELECT " + SDS + ".\"CD_ID\", count(1) "
+        "SELECT " + SDS + ".\"CD_ID\" "
             + "from " + SDS + " "
             + "WHERE " + SDS + ".\"CD_ID\" in (" + colIds + ") "
             + "GROUP BY " + SDS + ".\"CD_ID\"";
-    List<Object> danglingColumnDescriptorIdList = new ArrayList<>(columnDescriptorIdList.size());
+    Set<Long> danglingColumnDescriptorIdSet = new HashSet<>(columnDescriptorIdList);
     try (QueryWrapper query = new QueryWrapper(pm.newQuery("javax.jdo.query.SQL", queryText))) {
-      List<Object[]> sqlResult = MetastoreDirectSqlUtils
-          .ensureList(executeWithArray(query, null, queryText));
+      List<Long> sqlResult = executeWithArray(query, null, queryText);
 
       if (!sqlResult.isEmpty()) {
-        for (Object[] fields : sqlResult) {
-          if (MetastoreDirectSqlUtils.extractSqlInt(fields[1]) == 0) {
-            danglingColumnDescriptorIdList.add(MetastoreDirectSqlUtils.extractSqlLong(fields[0]));
-          }
+        for (Long cdId : sqlResult) {
+          // the returned CD is not dangling, so remove it from the list
+          danglingColumnDescriptorIdSet.remove(cdId);
         }
       }
     }
-    if (!danglingColumnDescriptorIdList.isEmpty()) {
+    if (!danglingColumnDescriptorIdSet.isEmpty()) {
       try {
-        String danglingCDIds = getIdListForIn(danglingColumnDescriptorIdList);
+        String danglingCDIds = getIdListForIn(Arrays.asList(danglingColumnDescriptorIdSet.toArray()));

Review comment:
       Would it be possible to change the input for the `getIdListForIn` to accept Collections, so no conversion is needed? 




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