Peter Vary created HIVE-23042:
---------------------------------
Summary: Merge queries to a single one for updating MIN_OPEN_TXNS
table
Key: HIVE-23042
URL: https://issues.apache.org/jira/browse/HIVE-23042
Project: Hive
Issue Type: Bug
Components: Transactions
Reporter: Peter Vary
Assignee: Peter Vary
When opening a new transaction we issue 2 queries to update the MIN_OPEN_TXN
table.
{code}
<SELECT MIN("TXN_ID") FROM "TXNS" WHERE "TXN_STATE" = 'o'>
<insert into "MIN_HISTORY_LEVEL" ("MHL_TXNID", "MHL_MIN_OPEN_TXNID")
values(763, 763)>
{code}
This could be archived with a single query faster, if we do not open
transactions in batch, like:
{code}
<INSERT INTO "MIN_HISTORY_LEVEL" ("MHL_TXNID", "MHL_MIN_OPEN_TXNID")
SELECT ?, MIN("TXN_ID") FROM "TXNS" WHERE "TXN_STATE" = 'o'>
{code}
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