[
https://issues.apache.org/jira/browse/PHOENIX-6141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17696384#comment-17696384
]
ASF GitHub Bot commented on PHOENIX-6141:
-----------------------------------------
jpisaac commented on code in PR #1575:
URL: https://github.com/apache/phoenix/pull/1575#discussion_r1125217986
##########
phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ChildLinkMetaDataObserver.java:
##########
@@ -0,0 +1,290 @@
+package org.apache.phoenix.coprocessor;
+
+import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.CellUtil;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.Delete;
+import org.apache.hadoop.hbase.client.Mutation;
+import org.apache.hadoop.hbase.client.Put;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.client.ResultScanner;
+import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.coprocessor.ObserverContext;
+import org.apache.hadoop.hbase.coprocessor.RegionCoprocessor;
+import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
+import org.apache.hadoop.hbase.coprocessor.RegionObserver;
+import org.apache.hadoop.hbase.regionserver.Region;
+import org.apache.hadoop.hbase.regionserver.RegionScanner;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.phoenix.jdbc.PhoenixDatabaseMetaData;
+import org.apache.phoenix.util.EnvironmentEdgeManager;
+import org.apache.phoenix.util.SchemaUtil;
+import org.apache.phoenix.util.ServerUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.sql.SQLException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Optional;
+
+import static org.apache.phoenix.query.QueryConstants.VERIFIED_BYTES;
+import static org.apache.phoenix.util.ScanUtil.getDummyResult;
+import static org.apache.phoenix.util.ScanUtil.getPageSizeMsForRegionScanner;
+import static org.apache.phoenix.util.ScanUtil.isDummy;
+import static
org.apache.phoenix.thirdparty.com.google.common.base.Preconditions.checkArgument;
+
+
+/**
+ * Coprocessor that verifies scanned rows of SYSTEM.CHILD_LINK table
+ */
+public class ChildLinkMetaDataObserver extends BaseScannerRegionObserver
implements RegionCoprocessor {
Review Comment:
@palashc I am assuming the verification is being done out of band right?
Any reason we do not want to reuse the ChildLinkMetaDataEndpoint coprocessor
instead of having a new one?
We can extend the ChildLinkMetaDataService to have a verifyRows method and
have this logic in there?
> Ensure consistency between SYSTEM.CATALOG and SYSTEM.CHILD_LINK
> ---------------------------------------------------------------
>
> Key: PHOENIX-6141
> URL: https://issues.apache.org/jira/browse/PHOENIX-6141
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 5.0.0, 4.15.0
> Reporter: Chinmay Kulkarni
> Assignee: Palash Chauhan
> Priority: Blocker
> Fix For: 5.2.0, 5.1.4
>
>
> Before 4.15, "CREATE/DROP VIEW" was an atomic operation since we were issuing
> batch mutations on just the 1 SYSTEM.CATALOG region. In 4.15 we introduced
> SYSTEM.CHILD_LINK to store the parent->child links and so a CREATE VIEW is no
> longer atomic since it consists of 2 separate RPCs (1 to SYSTEM.CHILD_LINK
> to add the linking row and another to SYSTEM.CATALOG to write metadata for
> the new view).
> If the second RPC i.e. the RPC to write metadata to SYSTEM.CATALOG fails
> after the 1st RPC has already gone through, there will be an inconsistency
> between both metadata tables. We will see orphan parent->child linking rows
> in SYSTEM.CHILD_LINK in this case. This can cause the following issues:
> # ALTER TABLE calls on the base table will fail
> # DROP TABLE without CASCADE will fail
> # The upgrade path has calls like UpgradeUtil.upgradeTable() which will fail
> # Any metadata consistency checks can be thrown off
> # Unnecessary extra storage of orphan links
> The first 3 issues happen because we wrongly deduce that a base table has
> child views due to the orphan linking rows.
> This Jira aims at trying to come up with a way to make mutations among
> SYSTEM.CATALOG and SYSTEM.CHILD_LINK an atomic transaction. We can use a
> 2-phase commit approach like in global indexing or also potentially explore
> using a transaction manager.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
