[ASTERIXDB-1626] Multiple global aggregations result in sub-optimal plan

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: COMP - Compiler
• Labels: soon
• Assignee: Yingyi Bu
• Reporter: Yingyi Bu
• Created: 02/Sep/16 05:30
• Updated: 17/Jun/17 00:00
• Resolved: 19/Sep/16 06:49

Description

query:

Select count(*), avg(I_ID) 
FROM  items;

istribute result [%0->$$24]
-- DISTRIBUTE_RESULT  |UNPARTITIONED|
  exchange
  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
    project ([$$24])
    -- STREAM_PROJECT  |UNPARTITIONED|
      assign [$$24] <- [function-call: asterix:closed-record-constructor, Args:[AString: {$1}, function-call: asterix:sql-count, Args:[%0->$$19], AString: {$2}, function-call: asterix:sql-avg, Args:[%0->$$23]]]
      -- ASSIGN  |UNPARTITIONED|
        project ([$$19, $$23])
        -- STREAM_PROJECT  |UNPARTITIONED|
          subplan {
                    aggregate [$$23] <- [function-call: asterix:listify, Args:[%0->$$22]]
                    -- AGGREGATE  |UNPARTITIONED|
                      assign [$$22] <- [function-call: asterix:field-access-by-name, Args:[%0->$$27, AString: {I_ID}]]
                      -- ASSIGN  |UNPARTITIONED|
                        assign [$$27] <- [function-call: asterix:field-access-by-index, Args:[%0->$$12, AInt32: {0}]]
                        -- ASSIGN  |UNPARTITIONED|
                          unnest $$12 <- function-call: asterix:scan-collection, Args:[%0->$$15]
                          -- UNNEST  |UNPARTITIONED|
                            nested tuple source
                            -- NESTED_TUPLE_SOURCE  |UNPARTITIONED|
                 }
          -- SUBPLAN  |UNPARTITIONED|
            project ([$$19, $$15])
            -- STREAM_PROJECT  |UNPARTITIONED|
              subplan {
                        aggregate [$$19] <- [function-call: asterix:listify, Args:[%0->$$18]]
                        -- AGGREGATE  |UNPARTITIONED|
                          unnest $$11 <- function-call: asterix:scan-collection, Args:[%0->$$15]
                          -- UNNEST  |UNPARTITIONED|
                            nested tuple source
                            -- NESTED_TUPLE_SOURCE  |UNPARTITIONED|
                     }
              -- SUBPLAN  |UNPARTITIONED|
                assign [$$18] <- [AInt64: {1}]
                -- ASSIGN  |UNPARTITIONED|
                  aggregate [$$15] <- [function-call: asterix:listify, Args:[%0->$$10]]
                  -- AGGREGATE  |UNPARTITIONED|
                    exchange
                    -- RANDOM_MERGE_EXCHANGE  |PARTITIONED|
                      project ([$$10])
                      -- STREAM_PROJECT  |PARTITIONED|
                        assign [$$10] <- [function-call: asterix:closed-record-constructor, Args:[AString: {items}, %0->$$7]]
                        -- ASSIGN  |PARTITIONED|
                          project ([$$7])
                          -- STREAM_PROJECT  |PARTITIONED|
                            exchange
                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                              data-scan []<-[$$25, $$7, $$26] <- CouchbaseAnalytics:items
                              -- DATASOURCE_SCAN  |PARTITIONED|
                                exchange
                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                                  empty-tuple-source
                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|