ngsg commented on code in PR #5771:
URL: https://github.com/apache/hive/pull/5771#discussion_r2176269578
##########
ql/src/java/org/apache/hadoop/hive/ql/metadata/SessionHiveMetaStoreClient.java:
##########
@@ -142,2416 +40,28 @@
* so the readers of the objects in these maps should have the most recent
view of the object.
* But again, could be fragile.
*/
-public class SessionHiveMetaStoreClient extends
HiveMetaStoreClientWithLocalCache implements IMetaStoreClient {
- private static final Logger LOG =
LoggerFactory.getLogger(SessionHiveMetaStoreClient.class);
-
+public class SessionHiveMetaStoreClient extends BaseMetaStoreClientProxy
implements IMetaStoreClient {
SessionHiveMetaStoreClient(Configuration conf, Boolean allowEmbedded) throws
MetaException {
- super(conf, null, allowEmbedded);
+ super(createUnderlyingClient(conf, null, allowEmbedded));
}
SessionHiveMetaStoreClient(
Configuration conf, HiveMetaHookLoader hookLoader, Boolean
allowEmbedded) throws MetaException {
- super(conf, hookLoader, allowEmbedded);
- }
-
- private Warehouse wh = null;
-
- private Warehouse getWh() throws MetaException {
- if (wh == null) {
- wh = new Warehouse(conf);
- }
- return wh;
- }
-
- @Override
- protected void create_table(CreateTableRequest request) throws TException {
- org.apache.hadoop.hive.metastore.api.Table tbl = request.getTable();
- if (tbl.isTemporary()) {
- createTempTable(tbl);
- return;
- }
- super.create_table(request);
- }
-
- @Override
- protected void drop_table_with_environment_context(String catName, String
dbname, String name,
- boolean deleteData, EnvironmentContext envContext) throws TException,
UnsupportedOperationException {
- // First try temp table
- // TODO CAT - I think the right thing here is to always put temp tables in
the current
- // catalog. But we don't yet have a notion of current catalog, so we'll
have to hold on
- // until we do.
- org.apache.hadoop.hive.metastore.api.Table table = getTempTable(dbname,
name);
- if (table != null) {
- try {
- deleteTempTableColumnStatsForTable(dbname, name);
- } catch (NoSuchObjectException err){
- // No stats to delete, forgivable error.
- LOG.info(err.getMessage());
- }
- dropTempTable(table, deleteData, envContext);
- return;
- }
-
- // Try underlying client
- super.drop_table_with_environment_context(catName, dbname, name,
deleteData, envContext);
- }
-
- @Override
- public void truncateTable(String dbName, String tableName, List<String>
partNames) throws TException {
- // First try temp table
- org.apache.hadoop.hive.metastore.api.Table table = getTempTable(dbName,
tableName);
- if (table != null) {
- truncateTempTable(table);
- return;
- }
- // Try underlying client
- super.truncateTable(dbName, tableName, partNames);
- }
-
- @Override
- public void truncateTable(TableName tableName, List<String> partNames)
throws TException {
- // First try temp table
- org.apache.hadoop.hive.metastore.api.Table table =
getTempTable(tableName.getDb(), tableName.getTable());
- if (table != null) {
- truncateTempTable(table);
- return;
- }
- // Try underlying client
- super.truncateTable(tableName, partNames);
- }
-
- @Override
- public void truncateTable(String dbName, String tableName,
Review Comment:
`SessionHiveMetaStoreClient` and `HiveMetaStoreClientWithLocalCache` are
working as feature layers in the current codebase, and I understand that the
name `SessionHiveMetaStoreClient` could be used for
`SessionMetaStoreClientProxy` in this context. However, I think it is better to
keep the current naming for the following reasons:
1. In the new design, the session layer is not directly exposed. Instead,
there are two additional layers, `HookEnabledMetaStoreClientProxy` and
`SynchronizedMetaStoreClientProxy`, that wrap `SessionMetaStoreClientProxy`.
Therefore, keeping `SessionMetaStoreClientProxy` and
`SessionHiveMetaStoreClient` separate helps simplify the MetaStoreClient
creation logic.
2. More importantly, the purpose of this JIRA is to resolve the blocker of
HIVE-12679. HIVE-12679 aims to support third-party catalogs and is currently
blocked as there is no way to provide session-level features on top of them. To
address this issue, this JIRA proposes composable MetaStoreClients so that we
can compose a third-party catalog with a session-level feature layer. For this
reason, I believe it makes sense to introduce a separate proxy class for
session-level features, which reduces coupling with `ThriftHiveMetaStoreClient`.
Regarding session-level features, `SessionMetaStoreClientProxy` provides all
the existing functionality, including temporary table handling, transactions,
and session-level caching. As far as I know, the only API originally exposed by
`SessionHiveMetaStoreClient` is `getTempTablesForDatabase`, which remains
intact. If there are any features from `SessionHiveMetaStoreClient` that I may
have missed, I would appreciate it if you could point them out.
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