Github user JamesRTaylor commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/12#discussion_r17769890
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/iterate/DefaultParallelIteratorRegionSplitter.java
---
@@ -117,121 +107,87 @@ public boolean apply(HRegionLocation location) {
}
protected List<KeyRange> genKeyRanges(List<HRegionLocation> regions) {
- if (regions.isEmpty()) {
- return Collections.emptyList();
+ if (regions.isEmpty()) { return Collections.emptyList(); }
+ Scan scan = context.getScan();
+ PTable table = this.tableRef.getTable();
+ byte[] defaultCF = SchemaUtil.getEmptyColumnFamily(table);
+ List<byte[]> gps = null;
+
+ if (table.getColumnFamilies().isEmpty()) {
+ // For sure we can get the defaultCF from the table
+ gps = table.getGuidePosts();
+ } else {
+ try {
+ if (scan.getFamilyMap().size() > 0) {
+ if (scan.getFamilyMap().containsKey(defaultCF)) { //
Favor using default CF if it's used in scan
+ gps =
table.getColumnFamily(defaultCF).getGuidePosts();
+ } else { // Otherwise, just use first CF in use by scan
+ gps =
table.getColumnFamily(scan.getFamilyMap().keySet().iterator().next()).getGuidePosts();
+ }
+ } else {
+ gps = table.getColumnFamily(defaultCF).getGuidePosts();
+ }
+ } catch (ColumnFamilyNotFoundException cfne) {
+ // Alter table does this
+ }
}
- StatsManager statsManager =
context.getConnection().getQueryServices().getStatsManager();
- // the splits are computed as follows:
- //
- // let's suppose:
- // t = target concurrency
- // m = max concurrency
- // r = the number of regions we need to scan
- //
- // if r >= t:
- // scan using regional boundaries
- // elif r > t/2:
- // split each region in s splits such that:
- // s = max(x) where s * x < m
- // else:
- // split each region in s splits such that:
- // s = max(x) where s * x < t
- //
- // The idea is to align splits with region boundaries. If rows are
not evenly
- // distributed across regions, using this scheme compensates for
regions that
- // have more rows than others, by applying tighter splits and
therefore spawning
- // off more scans over the overloaded regions.
- int splitsPerRegion = getSplitsPerRegion(regions.size());
- // Create a multi-map of ServerName to List<KeyRange> which we'll
use to round robin from to ensure
- // that we keep each region server busy for each query.
- ListMultimap<HRegionLocation,KeyRange> keyRangesPerRegion =
ArrayListMultimap.create(regions.size(),regions.size() * splitsPerRegion);;
- if (splitsPerRegion == 1) {
+ List<KeyRange> guidePosts =
Lists.newArrayListWithCapacity(regions.size());
+ List<KeyRange> regionStartEndKey =
Lists.newArrayListWithExpectedSize(regions.size());
+ if (gps == null || gps.isEmpty()) {
+ if (logger.isDebugEnabled()) {
+ logger.debug("The splits formed from region start and
endkeys are: " + regionStartEndKey);
+ }
for (HRegionLocation region : regions) {
- keyRangesPerRegion.put(region,
ParallelIterators.TO_KEY_RANGE.apply(region));
+
regionStartEndKey.add(KeyRange.getKeyRange(region.getRegionInfo().getStartKey(),
region.getRegionInfo()
+ .getEndKey()));
}
+ return regionStartEndKey;
} else {
--- End diff --
Thanks for the review of my review, @ramkrish86. I believe this will work
to replace the if/else. What do you think?
byte[] currentKey = regions.get(0).getRegionInfo().getStartKey();
byte[] endKey = null;
int regionIndex = 0;
int guideIndex = 0;
int gpsSize = gps.size();
int regionSize = regions.size();
guideIndex = currentKey.length == 0 ? 0 :
Collections.binarySearch(gps, currentKey, Bytes.BYTES_COMPARATOR);
// Merge bisect with guideposts for all but the last region
while (regionIndex < regionSize) {
byte[] currentGuidePost;
endKey = regions.get(regionIndex++).getRegionInfo().getEndKey();
while (guideIndex < gpsSize &&
(Bytes.compareTo(currentGuidePost = gps.get(guideIndex), endKey) <= 0 ||
endKey.length == 0)) {
KeyRange keyRange = KeyRange.getKeyRange(currentKey,
currentGuidePost);
if (keyRange != KeyRange.EMPTY_RANGE) {
guidePosts.add(keyRange);
}
currentKey = currentGuidePost;
guideIndex++;
}
KeyRange keyRange = KeyRange.getKeyRange(currentKey, endKey);
if (keyRange != KeyRange.EMPTY_RANGE) {
guidePosts.add(keyRange);
}
currentKey = endKey;
}
if (logger.isDebugEnabled()) {
logger.debug("The captured guideposts are: " + guidePosts);
}
return guidePosts;
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