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https://issues.apache.org/jira/browse/HIVE-25779?focusedWorklogId=795646&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-795646
 ]

ASF GitHub Bot logged work on HIVE-25779:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 27/Jul/22 12:50
            Start Date: 27/Jul/22 12:50
    Worklog Time Spent: 10m 
      Work Description: hsnusonic commented on code in PR #3221:
URL: https://github.com/apache/hive/pull/3221#discussion_r931021355


##########
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/MetaStoreDirectSql.java:
##########
@@ -2635,10 +2634,9 @@ private void dropPartitionsByPartitionIds(List<Long> 
partitionIdList) throws Met
         for (Object[] fields : sqlResult) {
           sdIdList.add(MetastoreDirectSqlUtils.extractSqlLong(fields[0]));
           Long colId = MetastoreDirectSqlUtils.extractSqlLong(fields[1]);
-          if (!columnDescriptorIdList.contains(colId)) {
-            columnDescriptorIdList.add(colId);
-          }
-          serdeIdList.add(MetastoreDirectSqlUtils.extractSqlLong(fields[2]));
+          columnDescriptorIdSet.add(colId);
+          Long serdeId = MetastoreDirectSqlUtils.extractSqlLong(fields[2]);
+          serdeIdSet.add(serdeId);

Review Comment:
   Sure, will do.





Issue Time Tracking
-------------------

    Worklog Id:     (was: 795646)
    Time Spent: 3h 50m  (was: 3h 40m)

> Deduplicate SerDe Info
> ----------------------
>
>                 Key: HIVE-25779
>                 URL: https://issues.apache.org/jira/browse/HIVE-25779
>             Project: Hive
>          Issue Type: New Feature
>          Components: Standalone Metastore
>            Reporter: Yu-Wen Lai
>            Assignee: Yu-Wen Lai
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 3h 50m
>  Remaining Estimate: 0h
>
> The proposal is that we can reuse serde info as how we reuse column 
> descriptors. (HIVE-2246)
> Currently, we store the metadata for partitions as PARTITIONS (N partitions) 
> -> SDS (N locations) -> SERDES (N entries). However,  all the SERDES for the 
> partitions in a table are the same if we don't explicitly specify it. That 
> is, each storage descriptor has a associated and exclusive serde info, but 
> the partitions' serde infos are mostly just the same as the table's. By 
> reusing the serde info, we can save some database storage and enhance the 
> query performance from HMS to the backend database.
> For backward compatibility, we also need to introduce a config for this 
> feature because there will be issues if HMS old instance and HMS new instance 
> with this feature are running together. With this feature, we will need to 
> check if others reference the serdes before deleting it, but the old instance 
> will just delete it.
> The other thing we need to take care of is custom serdes. If a partition's 
> serde is modified, we need to create a new record in SERDES so that we don't 
> interfere other partitions.



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