HIVE-27190: Fix cache-key collisions for time-travel queries on Iceberg (apache#6380)

Author: deniskuzZ

iceberg/iceberg-handler/src/test/queries/positive/iceberg_partition_pruner_cache_key.q

@@ -0,0 +1,50 @@
+set hive.fetch.task.conversion=none;
+set hive.explain.user=false;
+
+create external table tbl_ice_pp_key(a int, b string)
+  partitioned by spec (a) stored by iceberg;
+
+insert into tbl_ice_pp_key values (1, 'one'), (2, 'two');
+alter table tbl_ice_pp_key create tag s1;
+
+insert into tbl_ice_pp_key values
+  (3, 'three'), (4, 'four'), (5, 'five'),
+  (6, 'six'), (7, 'seven'),(8, 'eight'),
+  (9, 'nine'),  (10, 'ten');
+
+explain select count(*) from tbl_ice_pp_key;
+select count(*) from tbl_ice_pp_key;
+
+explain select count(*) from tbl_ice_pp_key for system_version as of 's1';
+select count(*) from tbl_ice_pp_key for system_version as of 's1';
+
+explain
+select cur.cnt as cur_cnt, snap.cnt as snap_cnt
+from (
+  select count(*) as cnt from tbl_ice_pp_key
+) cur
+cross join (
+  select count(*) as cnt from tbl_ice_pp_key for system_version as of 's1'
+) snap;
+
+select cur.cnt as cur_cnt, snap.cnt as snap_cnt
+from (
+  select count(*) as cnt from tbl_ice_pp_key
+) cur
+cross join (
+  select count(*) as cnt from tbl_ice_pp_key for system_version as of 's1'
+) snap;
+
+-- with a partition predicate
+explain
+select 'current' as ver, count(*) as cnt from tbl_ice_pp_key where a > 2
+union all
+select 'asof_s1' as ver, count(*) as cnt from tbl_ice_pp_key for system_version as of 's1'
+where a > 2;
+
+select 'current' as ver, count(*) as cnt from tbl_ice_pp_key where a > 2
+union all
+select 'asof_s1' as ver, count(*) as cnt from tbl_ice_pp_key for system_version as of 's1'
+where a > 2;
+
+drop table tbl_ice_pp_key;

iceberg/iceberg-handler/src/test/results/positive/iceberg_metadata_table_alias.q.out

@@ -23,7 +23,7 @@ POSTHOOK: type: QUERY
 POSTHOOK: Input: default@ice_t
 POSTHOOK: Output: hdfs://### HDFS PATH ###
 OPTIMIZED SQL: SELECT `committed_at` AS `ice_t.snapshots.committed_at`, `snapshot_id` AS `ice_t.snapshots.snapshot_id`, `parent_id` AS `ice_t.snapshots.parent_id`, `operation` AS `ice_t.snapshots.operation`, `manifest_list` AS `ice_t.snapshots.manifest_list`, `summary` AS `ice_t.snapshots.summary`
-FROM `default`.`ice_t`
+FROM `default`.`ice_t`.`snapshots`
 STAGE DEPENDENCIES:
   Stage-0 is a root stage