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https://issues.apache.org/jira/browse/HIVE-25779?focusedWorklogId=789383&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-789383
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ASF GitHub Bot logged work on HIVE-25779:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 11/Jul/22 07:14
Start Date: 11/Jul/22 07:14
Worklog Time Spent: 10m
Work Description: dengzhhu653 commented on code in PR #3221:
URL: https://github.com/apache/hive/pull/3221#discussion_r917610133
##########
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/conf/MetastoreConf.java:
##########
@@ -1276,6 +1276,9 @@ public enum ConfVars {
"hive.metastore.serdes.without.from.deserializer",
"org.apache.iceberg.mr.hive.HiveIcebergSerDe",
"SerDes which are providing the schema but do not need the 'from
deserializer' comment for the columns."),
+ USE_TABLE_SERDES("metastore.use.table.serdes",
Review Comment:
not sure if we can turn on the feature by default, since this is a good
performance improvement.
Issue Time Tracking
-------------------
Worklog Id: (was: 789383)
Time Spent: 2h 40m (was: 2.5h)
> 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: 2h 40m
> 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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