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https://issues.apache.org/jira/browse/HIVE-27186?focusedWorklogId=861008&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-861008
]
ASF GitHub Bot logged work on HIVE-27186:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 08/May/23 13:15
Start Date: 08/May/23 13:15
Worklog Time Spent: 10m
Work Description: henrib commented on code in PR #4194:
URL: https://github.com/apache/hive/pull/4194#discussion_r1187433359
##########
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/PropertyMap.java:
##########
@@ -0,0 +1,466 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hive.metastore.properties;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.io.InvalidObjectException;
+import java.io.ObjectInputStream;
+import java.io.ObjectStreamException;
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Properties;
+import java.util.TreeMap;
+import java.util.UUID;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+
+/**
+ * A property map pertaining to a given object type (cluster, database, table).
+ * <p>
+ * Maps follow a copy-on-write scheme gated by a dirty flag (avoid copy of a
dirty map). This allows
+ * sharing their content (the inner properties map) with guaranteed
isolation and thread safety.
+ * </p>
+ */
+public class PropertyMap implements Serializable {
Review Comment:
The idea behind the serialization proxy is that of a convention; the
'contract' does not need to be made explicit through inheritance. Adding an
abstract class for one use case that is already provably following a convention
does not bring any clarity imho.
Issue Time Tracking
-------------------
Worklog Id: (was: 861008)
Time Spent: 17h 10m (was: 17h)
> A persistent property store
> ----------------------------
>
> Key: HIVE-27186
> URL: https://issues.apache.org/jira/browse/HIVE-27186
> Project: Hive
> Issue Type: Improvement
> Components: Metastore
> Affects Versions: 4.0.0-alpha-2
> Reporter: Henri Biestro
> Assignee: Henri Biestro
> Priority: Major
> Labels: pull-request-available
> Time Spent: 17h 10m
> Remaining Estimate: 0h
>
> WHAT
> A persistent property store usable as a support facility for any metadata
> augmentation feature.
> WHY
> When adding new meta-data oriented features, we usually need to persist
> information linking the feature data and the HiveMetaStore objects it applies
> to. Any information related to a database, a table or the cluster - like
> statistics for example or any operational data state or data (think rolling
> backup) - fall in this use-case.
> Typically, accommodating such a feature requires modifying the Metastore
> database schema by adding or altering a table. It also usually implies
> modifying the thrift APIs to expose such meta-data to consumers.
> The proposed feature wants to solve the persistence and query/transport for
> these types of use-cases by exposing a 'key/(meta)value' store exposed as a
> property system.
> HOW
> A property-value model is the simple and generic exposed API.
> To provision for several usage scenarios, the model entry point is a
> 'namespace' that qualifies the feature-component property manager. For
> example, 'stats' could be the namespace for all properties related to the
> 'statistics' feature.
> The namespace identifies a manager that handles property-groups persisted as
> property-maps. For instance, all statistics pertaining to a given table would
> be collocated in the same property-group. As such, all properties (say number
> of 'unique_values' per columns) for a given HMS table 'relation0' would all
> be stored and persisted in the same property-map instance.
> Property-maps may be decorated by an (optional) schema that may declare the
> name and value-type of allowed properties (and their optional default value).
> Each property is addressed by a name, a path uniquely identifying the
> property in a given property map.
> The manager also handles transforming property-map names to the property-map
> keys used to persist them in the DB.
> The API provides inserting/updating properties in bulk transactionally. It
> also provides selection/projection to help reduce the volume of exchange
> between client/server; selection can use (JEXL expression) predicates to
> filter maps.
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