[
https://issues.apache.org/jira/browse/HIVE-23597?focusedWorklogId=452175&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-452175
]
ASF GitHub Bot logged work on HIVE-23597:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 29/Jun/20 05:43
Start Date: 29/Jun/20 05:43
Worklog Time Spent: 10m
Work Description: pvary commented on a change in pull request #1081:
URL: https://github.com/apache/hive/pull/1081#discussion_r446784234
##########
File path:
ql/src/java/org/apache/hadoop/hive/ql/io/orc/VectorizedOrcAcidRowBatchReader.java
##########
@@ -1605,6 +1618,46 @@ public int compareTo(CompressedOwid other) {
throw e; // rethrow the exception so that the caller can handle.
}
}
+
+ /**
+ * Create delete delta reader. Caching orc tail to avoid FS lookup/reads
for repeated scans.
+ *
+ * @param deleteDeltaFile
+ * @param conf
+ * @param fs FileSystem
+ * @return delete file reader
+ * @throws IOException
+ */
+ private Reader getDeleteDeltaReader(Path deleteDeltaFile, JobConf conf,
FileSystem fs) throws IOException {
+ OrcTail deleteDeltaTail =
deleteDeltaOrcTailCache.getIfPresent(deleteDeltaFile);
Review comment:
Is the OrcTail thread safe? If I understandcorrectly the tail will be
read by multiple LLAP threads concurrenly
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Issue Time Tracking
-------------------
Worklog Id: (was: 452175)
Time Spent: 1h 10m (was: 1h)
> VectorizedOrcAcidRowBatchReader::ColumnizedDeleteEventRegistry reads delete
> delta directories multiple times
> ------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-23597
> URL: https://issues.apache.org/jira/browse/HIVE-23597
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> [https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/io/orc/VectorizedOrcAcidRowBatchReader.java#L1562]
> {code:java}
> try {
> final Path[] deleteDeltaDirs = getDeleteDeltaDirsFromSplit(orcSplit);
> if (deleteDeltaDirs.length > 0) {
> int totalDeleteEventCount = 0;
> for (Path deleteDeltaDir : deleteDeltaDirs) {
> {code}
>
> Consider a directory layout like the following. This was created by having
> simple set of "insert --> update --> select" queries.
>
> {noformat}
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/base_0000001
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/base_0000002
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000003_0000003_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000004_0000004_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000005_0000005_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000006_0000006_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000007_0000007_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000008_0000008_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000009_0000009_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000010_0000010_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000011_0000011_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000012_0000012_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000013_0000013_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000003_0000003_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000004_0000004_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000005_0000005_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000006_0000006_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000007_0000007_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000008_0000008_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000009_0000009_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000010_0000010_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000011_0000011_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000012_0000012_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000013_0000013_0000
> {noformat}
>
> Orcsplit contains all the delete delta folder information. For the directory
> layout like this, it would create {{~12 splits}}. For every split, it
> constructs "ColumnizedDeleteEventRegistry" in VRBAcidReader and ends up
> reading all these delete delta folders multiple times.
> In this case, it would read it approximately {{121 times!}}.
> This causes huge delay in running simple queries like "{{select * from
> tab_x}}" in cloud storage.
>
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