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Posted to dev@drill.apache.org by vkorukanti <gi...@git.apache.org> on 2015/10/02 01:32:51 UTC
[GitHub] drill pull request: DRILL-3884: Fix lower parallelization issues w...
GitHub user vkorukanti opened a pull request:
https://github.com/apache/drill/pull/185
DRILL-3884: Fix lower parallelization issues with Hive's native scan.
@amansinha100 Could you please review the patch?
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/vkorukanti/drill DRILL-3884
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/185.patch
To close this pull request, make a commit to your master/trunk branch
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This closes #185
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commit cdd71f1f2aa224f65147e084d75eacbc4ff7285b
Author: vkorukanti <ve...@gmail.com>
Date: 2015-10-01T22:15:12Z
DRILL-3884: Fix lower parallelization issues with Hive's native scan.
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[GitHub] drill pull request: DRILL-3884: Fix lower parallelization issues w...
Posted by amansinha100 <gi...@git.apache.org>.
Github user amansinha100 commented on the pull request:
https://github.com/apache/drill/pull/185#issuecomment-144884113
+1 LGTM.
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[GitHub] drill pull request: DRILL-3884: Fix lower parallelization issues w...
Posted by vkorukanti <gi...@git.apache.org>.
Github user vkorukanti commented on a diff in the pull request:
https://github.com/apache/drill/pull/185#discussion_r40982402
--- Diff: contrib/storage-hive/core/src/main/java/org/apache/drill/exec/store/hive/HiveScan.java ---
@@ -319,16 +319,12 @@ public ScanStats getScanStats() {
estRowCount = data/1024;
}
- // Hive's native reader is neither memory efficient nor fast. If the rowcount is below
- // HIVE_SERDE_SCAN_OVERHEAD_FACTOR, make sure it is at least HIVE_SERDE_SCAN_OVERHEAD_FACTOR to enable the planner
- // to choose HiveDrillNativeParquetScan. Due to the project on top of HiveDrillNativeParquetScan, we end up
- // choosing the HiveScan instead of HiveDrillNativeParquetScan if the cost is too low.
- if (estRowCount <= HIVE_SERDE_SCAN_OVERHEAD_FACTOR) {
- estRowCount = HIVE_SERDE_SCAN_OVERHEAD_FACTOR;
- }
+ // Hive's native reader is neither memory efficient nor fast. Increase the CPU cost
+ // by a factor to let the planner choose HiveDrillNativeScan over HiveScan with SerDes.
+ float cpuCost = 1 * HIVE_SERDE_SCAN_OVERHEAD_FACTOR;
--- End diff --
Fixed in updated patch.
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[GitHub] drill pull request: DRILL-3884: Fix lower parallelization issues w...
Posted by amansinha100 <gi...@git.apache.org>.
Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/185#discussion_r40981727
--- Diff: contrib/storage-hive/core/src/main/java/org/apache/drill/exec/store/hive/HiveScan.java ---
@@ -319,16 +319,12 @@ public ScanStats getScanStats() {
estRowCount = data/1024;
}
- // Hive's native reader is neither memory efficient nor fast. If the rowcount is below
- // HIVE_SERDE_SCAN_OVERHEAD_FACTOR, make sure it is at least HIVE_SERDE_SCAN_OVERHEAD_FACTOR to enable the planner
- // to choose HiveDrillNativeParquetScan. Due to the project on top of HiveDrillNativeParquetScan, we end up
- // choosing the HiveScan instead of HiveDrillNativeParquetScan if the cost is too low.
- if (estRowCount <= HIVE_SERDE_SCAN_OVERHEAD_FACTOR) {
- estRowCount = HIVE_SERDE_SCAN_OVERHEAD_FACTOR;
- }
+ // Hive's native reader is neither memory efficient nor fast. Increase the CPU cost
+ // by a factor to let the planner choose HiveDrillNativeScan over HiveScan with SerDes.
+ float cpuCost = 1 * HIVE_SERDE_SCAN_OVERHEAD_FACTOR;
--- End diff --
I am thinking this cost should include the number of columns as well...suppose there are lots of columns(e.g 500), we want both types of plans to be equally penalized.
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[GitHub] drill pull request: DRILL-3884: Fix lower parallelization issues w...
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/drill/pull/185
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