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https://issues.apache.org/jira/browse/PHOENIX-5069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16736551#comment-16736551
]
ASF GitHub Bot commented on PHOENIX-5069:
-----------------------------------------
Github user karanmehta93 commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/425#discussion_r245852009
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/query/PhoenixStatsLoader.java ---
@@ -0,0 +1,47 @@
+/*
+ * 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.phoenix.query;
+
+import org.apache.phoenix.schema.stats.GuidePostsInfo;
+import org.apache.phoenix.schema.stats.GuidePostsKey;
+
+/**
+ * The interface for talking to underneath layers to load stats from stats
table for a given key
+ */
+public interface PhoenixStatsLoader {
+ /**
+ * Use to check whether this is the time to load stats from stats
table.
+ * There are two cases:
+ * a. After a specified duration has passed
+ * b. The stats on server side (e.g. in stats table) has been updated
+ *
+ * @return boolean indicates whether we need to load stats or not
+ */
+ boolean needsLoad();
+
+ /**
+ * Called by ring buffer event handler to write RingBufferEvent
--- End diff --
Is this relevant?
> Use asynchronous refresh to provide non-blocking Phoenix Stats Client Cache
> ---------------------------------------------------------------------------
>
> Key: PHOENIX-5069
> URL: https://issues.apache.org/jira/browse/PHOENIX-5069
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Bin Shi
> Assignee: Bin Shi
> Priority: Major
>
> The current Phoenix Stats Cache uses TTL based eviction policy. A cached
> entry will expire after a given amount of time (900s by default) passed since
> the entry's been created. This will lead to cache miss when
> Compiler/Optimizer fetches stats from cache at the next time. As you can see
> from the above graph, fetching stats from the cache is a blocking operation —
> when there is cache miss, it has a round trip over the wire to scan the
> SYSTEM.STATS Table and to get the latest stats info, rebuild the cache and
> finally return the stats to the Compiler/Optimizer. Whenever there is a cache
> miss, this blocking call causes significant performance penalty and see
> periodic spikes.
> *This Jira suggests to use asynchronous refresh mechanism to provide a
> non-blocking cache. For details, please see the linked design document below.*
> [~karanmehta93] [[email protected]] [~dbwong] [~elserj] [[email protected]]
> [~sergey soldatov]
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