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https://issues.apache.org/jira/browse/HIVE-25779?focusedWorklogId=792785&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-792785
]
ASF GitHub Bot logged work on HIVE-25779:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 19/Jul/22 16:01
Start Date: 19/Jul/22 16:01
Worklog Time Spent: 10m
Work Description: saihemanth-cloudera commented on code in PR #3221:
URL: https://github.com/apache/hive/pull/3221#discussion_r924692232
##########
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/ObjectStore.java:
##########
@@ -5425,6 +5492,55 @@ private void
removeUnusedColumnDescriptor(MColumnDescriptor oldCD) {
}
}
+ /**
+ * Checks if a serde info has any remaining references by storage descriptors
+ * in the db. If it does not, then delete the SerDe info. If it does, then
do nothing.
+ * @param oldSerDeInfo the serde info to delete if it is no longer
referenced anywhere
+ */
+ private void removeUnusedSerDeInfo(MSerDeInfo oldSerDeInfo) {
+ if (oldSerDeInfo == null) {
+ return;
+ }
+ LOG.debug("executing removeUnusedSerDeInfo");
Review Comment:
Wouldn't it be ideal to log the value of the oldSerDeInfo variable in the
debug message?
Issue Time Tracking
-------------------
Worklog Id: (was: 792785)
Time Spent: 3h 20m (was: 3h 10m)
> 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 20m
> 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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