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https://issues.apache.org/jira/browse/PHOENIX-1224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14121618#comment-14121618
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Kyle Buzsaki commented on PHOENIX-1224:
---------------------------------------
Did some logging to diagnose the issue, and it looks like the skip scans get
trapped in a loop that looks like this:
{code}
filterKeyValue call with Key Value:
\x03\x80\x00\x00\x03\x80\x00\x00\x04\x80\x00\x00\x05/0:COL3/1409851622400/Put/vlen=4/mvcc=2
Return Code: SEEK_NEXT_USING_HINT, hint:
\x03\x80\x00\x00\x03\x80\x00\x00\x04//LATEST_TIMESTAMP/Maximum/vlen=0/mvcc=0
filterKeyValue call with Key Value:
\x03\x80\x00\x00\x03\x80\x00\x00\x04\x80\x00\x00\x05/0:COL3/1409851622400/Put/vlen=4/mvcc=2
Return Code: SEEK_NEXT_USING_HINT, hint:
\x03\x80\x00\x00\x03\x80\x00\x00\x04//LATEST_TIMESTAMP/Maximum/vlen=0/mvcc=0
filterKeyValue call with Key Value:
\x03\x80\x00\x00\x03\x80\x00\x00\x04\x80\x00\x00\x05/0:COL3/1409851622400/Put/vlen=4/mvcc=2
Return Code: SEEK_NEXT_USING_HINT, hint:
\x03\x80\x00\x00\x03\x80\x00\x00\x04//LATEST_TIMESTAMP/Maximum/vlen=0/mvcc=0
{code}
That is, the skip scan filter is passed a particular row key to filter, it
returns the SEEK_NEXT_USING_HINT return code, but the 'hint' key that it
returns is BEFORE the row key it was given in the first place.
{code}
\x03\x80\x00\x00\x03\x80\x00\x00\x04\x80\x00\x00\x05/0 // rowkey
\x03\x80\x00\x00\x03\x80\x00\x00\x04 // hint key
{code}
I'm trying to figure out now how that hint key is calculated and how we can fix
it. It seems like the correct hint to return in this case would be one
incremented
{code}
\x03\x80\x00\x00\x03\x80\x00\x00\x05
{code}
So it seems like we just need to identify whether the skip scan is not fully
qualified, and if it is NOT fully qualified, then to increment this hint key by
one.
Thoughts / advice?
> Dead loop in hbase scan when hint SKIP_SCAN is set and there is partial key
> match in RowValueConstructor
> --------------------------------------------------------------------------------------------------------
>
> Key: PHOENIX-1224
> URL: https://issues.apache.org/jira/browse/PHOENIX-1224
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 3.0.0, 4.0.0, 5.0.0
> Reporter: Maryann Xue
> Assignee: Kyle Buzsaki
> Original Estimate: 48h
> Remaining Estimate: 48h
>
> The below test will end up in dead loop in hbase scan.
> {code}
> @Test
> public void testForceSkipScan() throws Exception {
> String tempTableWithCompositePK = "TEMP_TABLE_COMPOSITE_PK";
> Properties props = PropertiesUtil.deepCopy(TEST_PROPERTIES);
> Connection conn = DriverManager.getConnection(getUrl(), props);
> try {
> conn.createStatement().execute("CREATE TABLE " +
> tempTableWithCompositePK
> + " (col0 INTEGER NOT NULL, "
> + " col1 INTEGER NOT NULL, "
> + " col2 INTEGER NOT NULL, "
> + " col3 INTEGER "
> + " CONSTRAINT pk PRIMARY KEY (col0, col1, col2)) "
> + " SALT_BUCKETS=4");
>
> PreparedStatement upsertStmt = conn.prepareStatement(
> "upsert into " + tempTableWithCompositePK + "(col0, col1,
> col2, col3) " + "values (?, ?, ?, ?)");
> for (int i = 0; i < 3; i++) {
> upsertStmt.setInt(1, i + 1);
> upsertStmt.setInt(2, i + 2);
> upsertStmt.setInt(3, i + 3);
> upsertStmt.setInt(4, i + 5);
> upsertStmt.execute();
> }
> conn.commit();
>
> String query = "SELECT /*+ SKIP_SCAN*/ * FROM " +
> tempTableWithCompositePK + " WHERE (col0, col1) in ((2, 3), (3, 4), (4, 5))";
> PreparedStatement statement = conn.prepareStatement(query);
> ResultSet rs = statement.executeQuery();
> assertTrue(rs.next());
> assertEquals(rs.getInt(1), 2);
> assertEquals(rs.getInt(2), 3);
> assertEquals(rs.getInt(3), 4);
> assertEquals(rs.getInt(4), 6);
> assertTrue(rs.next());
> assertEquals(rs.getInt(1), 3);
> assertEquals(rs.getInt(2), 4);
> assertEquals(rs.getInt(3), 5);
> assertEquals(rs.getInt(4), 7);
> assertFalse(rs.next());
> } finally {
> conn.close();
> }
> }
> {code}
> The dead-loop thread:
> {panel}
> "defaultRpcServer.handler=4,queue=0,port=58945" daemon prio=10
> tid=0x00007fe4d408c000 nid=0x7bba runnable [0x00007fe4c10cf000]
> java.lang.Thread.State: RUNNABLE
> at java.util.ArrayList.size(ArrayList.java:177)
> at java.util.AbstractList$Itr.hasNext(AbstractList.java:339)
> at
> org.apache.hadoop.hbase.filter.FilterList.filterAllRemaining(FilterList.java:199)
> at
> org.apache.hadoop.hbase.regionserver.ScanQueryMatcher.match(ScanQueryMatcher.java:263)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.next(StoreScanner.java:469)
> at
> org.apache.hadoop.hbase.regionserver.KeyValueHeap.next(KeyValueHeap.java:140)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.populateResult(HRegion.java:3937)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:4017)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:3885)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:3876)
> at
> org.apache.phoenix.coprocessor.ScanRegionObserver$2.nextRaw(ScanRegionObserver.java:366)
> at
> org.apache.phoenix.coprocessor.DelegateRegionScanner.nextRaw(DelegateRegionScanner.java:76)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.scan(HRegionServer.java:3157)
> - locked <0x0000000778d5dbd8> (a
> org.apache.phoenix.coprocessor.BaseScannerRegionObserver$1)
> at
> org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:29497)
> at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2027)
> at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:98)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:114)
> at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:94)
> at java.lang.Thread.run(Thread.java:662)
> {panel}
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