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https://issues.apache.org/jira/browse/PHOENIX-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16023267#comment-16023267
]
ASF GitHub Bot commented on PHOENIX-3744:
-----------------------------------------
Github user JamesRTaylor commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/239#discussion_r118312938
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/iterate/DefaultParallelScanGrouper.java
---
@@ -17,46 +17,79 @@
*/
package org.apache.phoenix.iterate;
+import java.sql.SQLException;
import java.util.List;
+import com.google.common.base.Preconditions;
+import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.phoenix.compile.QueryPlan;
+import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.schema.PTable;
import org.apache.phoenix.schema.PTable.IndexType;
import org.apache.phoenix.schema.SaltingUtil;
+import org.apache.phoenix.schema.TableRef;
import org.apache.phoenix.util.ScanUtil;
/**
* Default implementation that creates a scan group if a plan is row key
ordered (which requires a merge sort),
- * or if a scan crosses a region boundary and the table is salted or a
local index.
+ * or if a scan crosses a region boundary and the table is salted or a
local index.
*/
public class DefaultParallelScanGrouper implements ParallelScanGrouper {
-
- private static final DefaultParallelScanGrouper INSTANCE = new
DefaultParallelScanGrouper();
- public static DefaultParallelScanGrouper getInstance() {
- return INSTANCE;
- }
-
- private DefaultParallelScanGrouper() {}
-
- @Override
- public boolean shouldStartNewScan(QueryPlan plan, List<Scan> scans,
byte[] startKey, boolean crossedRegionBoundary) {
- PTable table = plan.getTableRef().getTable();
- boolean startNewScanGroup = false;
- if (!plan.isRowKeyOrdered()) {
- startNewScanGroup = true;
- } else if (crossedRegionBoundary) {
- if (table.getIndexType() == IndexType.LOCAL) {
- startNewScanGroup = true;
- } else if (table.getBucketNum() != null) {
- startNewScanGroup = scans.isEmpty() ||
- ScanUtil.crossesPrefixBoundary(startKey,
-
ScanUtil.getPrefix(scans.get(scans.size()-1).getStartRow(),
SaltingUtil.NUM_SALTING_BYTES),
- SaltingUtil.NUM_SALTING_BYTES);
- }
- }
- return startNewScanGroup;
+ private static DefaultParallelScanGrouper INSTANCE = new
DefaultParallelScanGrouper();
--- End diff --
I don't think that DefaultParallelScanGrouper can be a singleton with the
state of context and tableName inside of it.
> Support snapshot scanners for MR-based queries
> ----------------------------------------------
>
> Key: PHOENIX-3744
> URL: https://issues.apache.org/jira/browse/PHOENIX-3744
> Project: Phoenix
> Issue Type: Bug
> Reporter: James Taylor
> Assignee: Akshita Malhotra
> Attachments: PHOENIX-3744.patch
>
>
> HBase support scanning over snapshots, with a SnapshotScanner that accesses
> the region directly in HDFS. We should make sure that Phoenix can support
> that.
> Not sure how we'd want to decide when to run a query over a snapshot. Some
> ideas:
> - if there's an SCN set (i.e. the query is running at a point in time in the
> past)
> - if the memstore is empty
> - if the query is being run at a timestamp earlier than any memstore data
> - as a config option on the table
> - as a query hint
> - based on some kind of optimizer rule (i.e. based on estimated # of bytes
> that will be scanned)
> Phoenix typically runs a query at the timestamp at which it was compiled. Any
> data committed after this time should not be seen while a query is running.
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