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From "Yingyi Bu (Code Review)" <do-not-re...@asterixdb.incubator.apache.org>
Subject Change in asterixdb[master]: ASTERIXDB-1892: Sets a proper hash table cardinality during ...
Date Mon, 01 May 2017 21:44:03 GMT
Yingyi Bu has posted comments on this change.

Change subject: ASTERIXDB-1892: Sets a proper hash table cardinality during hash-group by
......................................................................


Patch Set 7:

(4 comments)

https://asterix-gerrit.ics.uci.edu/#/c/1702/5/hyracks-fullstack/hyracks/hyracks-dataflow-std/src/main/java/org/apache/hyracks/dataflow/std/structures/SerializableHashTable.java
File hyracks-fullstack/hyracks/hyracks-dataflow-std/src/main/java/org/apache/hyracks/dataflow/std/structures/SerializableHashTable.java:

PS5, Line 268: length
headers.length --> requireHeaderFrameCompaction.length()

https://docs.oracle.com/javase/7/docs/api/java/util/BitSet.html#length()


https://asterix-gerrit.ics.uci.edu/#/c/1702/7/hyracks-fullstack/hyracks/hyracks-dataflow-std/src/main/java/org/apache/hyracks/dataflow/std/structures/SerializableHashTable.java
File hyracks-fullstack/hyracks/hyracks-dataflow-std/src/main/java/org/apache/hyracks/dataflow/std/structures/SerializableHashTable.java:

PS7, Line 86: markHeaderFrameDirty
markHeaderFrameDirty -> markHeaderFrameReclaimable

It feels requireHeaderFrameCompaction can help very little -- a header is set even when there
is only 2 bytes available but to reclaim it you need every byte available.

I think there's better way to achieve this, e.g., maintain a used-slot-count in the header
frame using the last four bytes.  In this way, you don't need to iterative over all bytes
in the header.  

Can we defer the GC of header to the next change and let this change only fix the OOM issue?


PS7, Line 268: headers
requireHeaderFrameCompaction.length()


PS7, Line 269: if
flip the if condition and reduce the nesting.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I651139b2b559ad4d2f6137a5c844814606516a90
Gerrit-PatchSet: 7
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: Taewoo Kim <wangsaeu@gmail.com>
Gerrit-Reviewer: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Gerrit-Reviewer: Taewoo Kim <wangsaeu@gmail.com>
Gerrit-Reviewer: Yingyi Bu <buyingyi@gmail.com>
Gerrit-HasComments: Yes

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