Miklos Szurap created HIVE-25074:
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Summary: Remove Metastore flushCache usage
Key: HIVE-25074
URL: https://issues.apache.org/jira/browse/HIVE-25074
Project: Hive
Issue Type: Improvement
Components: Metastore, Standalone Metastore
Affects Versions: 4.0.0
Reporter: Miklos Szurap
The "flushCache" in HiveMetaStore with the ObjectStore implementation is
currently a NOOP:
{code:java}
public void flushCache() {
// NOP as there's no caching
} {code}
The HBaseStore (HBaseReadWrite) had some logic in it, however it has been
removed in HIVE-17234.
As I see the calls are going like this:
HiveMetaStoreClient.flushCache() -> CachedStore.flushCache() ->
ObjectStore.flushCache()
There are significant amount of calls (about 10% of all calls) made from the
client to the server - to do nothing. We could spare the call to the server
completely, including getting a DB connection which can take 1+ seconds under
high load scenarios slowing down Hive queries unnecessarily.
Can we:
# Deprecate the RawStore.flushCache (if there are other implementations)
# Deprecate the HiveMetaStoreClient.flushCache()
# Do the NOOP on the client side in HiveMetaStoreClient.flushCache() (while it
is not removed in a next version)
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