[IMPALA-3111] Selecting collection types returns json output rather than analysis error

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: Impala 2.3.0
• Fix Version/s: Not Applicable
• Component/s: Frontend
• Labels: complextype
• Target Version: Product Backlog
• Assignee: Unassigned
• Reporter: Matthew Jacobs
• Created: 01/Mar/16 22:33
• Updated: 13/Mar/20 13:46
• Resolved: 13/Mar/20 13:46

Description

Today, an outermost select list may not return collection types-- Impala now throws an AnalysisException.

E.g.

[localhost:21000] > select c_orders from tpch_nested_parquet.customer limit 1;
Query: select c_orders from tpch_nested_parquet.customer limit 1
ERROR: AnalysisException: Expr 'c_orders' in select list returns a complex type 'ARRAY<STRUCT<o_orderkey:BIGINT,o_orderstatus:STRING,o_totalprice:DECIMAL(12,2),o_orderdate:STRING,o_orderpriority:STRING,o_clerk:STRING,o_shippriority:INT,o_comment:STRING,o_lineitems:ARRAY<STRUCT<l_partkey:BIGINT,l_suppkey:BIGINT,l_linenumber:INT,l_quantity:DECIMAL(12,2),l_extendedprice:DECIMAL(12,2),l_discount:DECIMAL(12,2),l_tax:DECIMAL(12,2),l_returnflag:STRING,l_linestatus:STRING,l_shipdate:STRING,l_commitdate:STRING,l_receiptdate:STRING,l_shipinstruct:STRING,l_shipmode:STRING,l_comment:STRING>>>>'.
Only scalar types are allowed in the select list.

Instead, we should support returning collection types in the outermost select list as json strings.

Issue Links

• duplicates: IMPALA-2777 Support complex-typed expressions in the select list
• is duplicated by: IMPALA-3479 "packed" complex types similar to Hive
• is related to: IMPALA-3060 Supports IS [NOT] NULL feature for complex types