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https://issues.apache.org/jira/browse/HIVE-11948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15009126#comment-15009126
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Alan Gates commented on HIVE-11948:
-----------------------------------
bq. There is a RB link for this patch, it may be easier to add comments there.
I know, I just don't like review board. It's harder to keep track of comments
and feedback because they're not in the JIRA. I look forward to moving to pull
requests someday so feedback and changes can be tracked in one place
conveniently.
bq. The change in TxnHandler.checkLock() regarding heratbeat is intentional...
Makes sense.
bq. TxnHander unlock(), around line 581...
My mistake, I was thinking that commit() called unlock(), but looking at the
code I see it does the unlocking itself, so only worrying about locks that are
not associated with a txn here makes sense.
bq. Since "dbProduct" is only set once per MS start I don't think this causes
any more connections to be taken out...
That's not what I was saying. I was saying for programmer convenience it would
make sense to change this to be:
{code}
determineDatabaseProduct(null);
{code}
and change determineDataProduct to be:
{code}
protected DatabaseProduct determineDatabaseProduct(Connection conn) throws
MetaException {
if (dbProduct == null) {
if (conn == null) {
// get connection...
}
try {
...
{code}
This is purely convenience and not necessary.
+1 for the patch.
> Investigate TxnHandler and CompactionTxnHandler to see where we improve
> concurrency
> -----------------------------------------------------------------------------------
>
> Key: HIVE-11948
> URL: https://issues.apache.org/jira/browse/HIVE-11948
> Project: Hive
> Issue Type: Bug
> Components: Transactions
> Affects Versions: 0.14.0
> Reporter: Eugene Koifman
> Assignee: Eugene Koifman
> Attachments: HIVE-11948.3.patch, HIVE-11948.4.patch,
> HIVE-11948.5.patch, HIVE-11948.6.patch, HIVE-11948.7.patch, HIVE-11948.patch
>
>
> at least some operations (or parts of operations) can run at READ_COMMITTED.
> CompactionTxnHandler.setRunAs()
> CompactionTxnHandler.findNextToCompact()
> if update stmt includes cq_state = '" + INITIATED_STATE + "'" in WHERE clause
> and logic to look for "next" candidate
> CompactionTxnHandler.markCompacted()
> perhaps add cq_state=WORKING_STATE in Where clause (mostly as an extra
> consistency check)
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