jinhyukify commented on code in PR #8134:
URL: https://github.com/apache/hbase/pull/8134#discussion_r3195153761
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hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableRecordReaderImpl.java:
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@@ -141,9 +143,64 @@ public void initialize(InputSplit inputsplit,
TaskAttemptContext context)
if (context != null) {
this.context = context;
}
+ initProgressBounds();
restart(scan.getStartRow());
}
+ /**
+ * Resolve the start/stop row keys used for progress estimation. The
TableInputFormat splitter
+ * sets start and stop row keys from region boundaries, so they are only
empty for the table's
+ * very first region (empty start) or last region (empty stop). In those
cases, probe the table to
+ * discover the actual first or last row key as an approximation.
+ */
+ private void initProgressBounds() {
+ if (context == null) {
+ return;
+ }
+ byte[] startRow = scan.getStartRow();
+ byte[] stopRow = scan.getStopRow();
+ if (startRow == null || startRow.length == 0) {
+ startRow = probeFirstRow();
+ }
+ if (stopRow == null || stopRow.length == 0) {
+ stopRow = probeLastRow();
+ }
+ Configuration conf = context.getConfiguration();
+ Class<? extends RowKeyProgress> progressClass =
conf.getClass(RowKeyProgress.PROGRESS_CLASS_KEY,
+ UniformRowKeyProgress.class, RowKeyProgress.class);
+ rowKeyProgress = ReflectionUtils.newInstance(progressClass, conf);
+ rowKeyProgress.setStartStopRows(startRow, stopRow);
+ }
+
+ private byte[] probeFirstRow() {
+ try {
+ Scan probeScan = new Scan(scan);
+ probeScan.setOneRowLimit();
+ try (ResultScanner probeScanner = htable.getScanner(probeScan)) {
+ Result result = probeScanner.next();
+ return result != null ? result.getRow() : null;
+ }
+ } catch (IOException e) {
+ LOG.warn("Failed to probe first row for progress estimation", e);
+ return null;
+ }
+ }
+
+ private byte[] probeLastRow() {
+ try {
+ Scan probeScan = new Scan(scan);
+ probeScan.setReversed(true);
+ probeScan.setOneRowLimit();
+ try (ResultScanner probeScanner = htable.getScanner(probeScan)) {
+ Result result = probeScanner.next();
+ return result != null ? result.getRow() : null;
+ }
Review Comment:
Nice catch. Fixed this part.
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