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https://issues.apache.org/jira/browse/PHOENIX-7106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17806160#comment-17806160
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ASF GitHub Bot commented on PHOENIX-7106:
-----------------------------------------
tkhurana commented on code in PR #1736:
URL: https://github.com/apache/phoenix/pull/1736#discussion_r1450808105
##########
phoenix-core-client/src/main/java/org/apache/phoenix/iterate/OffsetResultIterator.java:
##########
@@ -32,32 +34,49 @@
*/
public class OffsetResultIterator extends DelegateResultIterator {
private int rowCount;
- private int offset;
+ private final int offset;
+ private Tuple lastScannedTuple;
private long pageSizeMs = Long.MAX_VALUE;
+ private boolean isIncompatibleClient = false;
public OffsetResultIterator(ResultIterator delegate, Integer offset) {
super(delegate);
this.offset = offset == null ? -1 : offset;
+ this.lastScannedTuple = null;
}
- public OffsetResultIterator(ResultIterator delegate, Integer offset, long
pageSizeMs) {
+ public OffsetResultIterator(ResultIterator delegate, Integer offset, long
pageSizeMs,
+ boolean isIncompatibleClient) {
this(delegate, offset);
this.pageSizeMs = pageSizeMs;
+ this.isIncompatibleClient = isIncompatibleClient;
}
+
@Override
public Tuple next() throws SQLException {
+ long startTime = EnvironmentEdgeManager.currentTimeMillis();
while (rowCount < offset) {
Tuple tuple = super.next();
- if (tuple == null) { return null; }
+ if (tuple == null) {
+ return null;
+ }
if (tuple.size() == 0 || isDummy(tuple)) {
// while rowCount < offset absorb the dummy and call next on
the underlying scanner
continue;
}
rowCount++;
- // no page timeout check at this level because we cannot correctly
resume
- // scans for OFFSET queries until the offset is reached
+ lastScannedTuple = tuple;
+ if (!isIncompatibleClient) {
+ if (EnvironmentEdgeManager.currentTimeMillis() - startTime >=
pageSizeMs) {
Review Comment:
Another issue with offset is that when the region moves the hbase client
will adjust the scan start key but it has no idea about the `OFFSET` attribute
so the new scan will start with the correct key but wrong offset. @virajjasani
are you handling this case ?
> Data Integrity issues due to invalid rowkeys returned by various coprocessors
> -----------------------------------------------------------------------------
>
> Key: PHOENIX-7106
> URL: https://issues.apache.org/jira/browse/PHOENIX-7106
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 5.2.0, 5.1.4
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Blocker
> Fix For: 5.2.0, 5.1.4
>
>
> HBase scanner interface expects server to perform scan of the cells from
> HFile or Block cache and return consistent data i.e. rowkey of the cells
> returned should stay in the range of the scan boundaries. When a region moves
> and scanner needs reset, or if the current row is too large and the server
> returns partial row, the subsequent scanner#next is supposed to return
> remaining cells. When this happens, cell rowkeys returned by servers i.e. any
> coprocessors is expected to be in the scan boundary range so that server can
> reliably perform its validation and return remaining cells as expected.
> Phoenix client initiates serial or parallel scans from the aggregators based
> on the region boundaries and the scan boundaries are sometimes adjusted based
> on where optimizer provided key ranges, to include tenant boundaries, salt
> boundaries etc. After the client opens the scanner and performs scan
> operation, some of the coprocs return invalid rowkey for the following cases:
> # Grouped aggregate queries
> # Some Ungrouped aggregate queries
> # Offset queries
> # Dummy cells returned with empty rowkey
> # Update statistics queries
> # Uncovered Index queries
> # Ordered results at server side
> # ORDER BY DESC on rowkey
> # Global Index read-repair
> # Paging region scanner with HBase scanner reopen
> # ORDER BY on non-pk column(s) with/without paging
> # GROUP BY on non-pk column(s) with/without paging
> Since many of these cases return reserved rowkeys, they are likely not going
> to match scan or region boundaries. It has potential to cause data integrity
> issues in certain scenarios as explained above. Empty rowkey returned by
> server can be treated as end of the region scan by HBase client.
> With the paging feature enabled, if the page size is kept low, we have higher
> chances of scanners returning dummy cell, resulting in increased num of RPC
> calls for better latency and timeouts. We should return only valid rowkey in
> the scan range for all the cases where we perform above mentioned operations
> like complex aggregate or offset queries etc.
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