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From "Jacques Nadeau (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-1861) Optimizer selects hash aggregate even when we have a sorted dataset
Date Sun, 04 Jan 2015 23:57:38 GMT

     [ https://issues.apache.org/jira/browse/DRILL-1861?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jacques Nadeau updated DRILL-1861:
----------------------------------
    Fix Version/s: 0.9.0
         Assignee: Jinfeng Ni

> Optimizer selects hash aggregate even when we have a sorted dataset
> -------------------------------------------------------------------
>
>                 Key: DRILL-1861
>                 URL: https://issues.apache.org/jira/browse/DRILL-1861
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Execution - Operators, Query Planning & Optimization
>            Reporter: Rahul Challapalli
>            Assignee: Jinfeng Ni
>             Fix For: 0.9.0
>
>         Attachments: wide-strings.parquet
>
>
> git.commit.id.abbrev=142e577
> Query :
> {code}
> select max(length(sub.str_var)) from ( select str_var, tinyint_var from `wide-strings`
order by tinyint_var) sub group by sub.tinyint_var;
> {code}
> Plan :
> {code}
> +------------+------------+
> |    text    |    json    |
> +------------+------------+
> | 00-00    Screen
> 00-01      Project(EXPR$0=[$1])
> 00-02        HashAgg(group=[{0}], EXPR$0=[MAX($1)])
> 00-03          Project(tinyint_var=[$1], $f1=[LENGTH($0)])
> 00-04            SelectionVectorRemover
> 00-05              Sort(sort0=[$1], dir0=[ASC])
> 00-06                Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/drill/testdata/data-shapes/wide-columns/flat/wide-strings]],
selectionRoot=/drill/testdata/data-shapes/wide-columns/flat/wide-strings, numFiles=1, columns=[`str_var`,
`tinyint_var`]]])
>  | {
>   "head" : {
>     "version" : 1,
>     "generator" : {
>       "type" : "ExplainHandler",
>       "info" : ""
>     },
>     "type" : "APACHE_DRILL_PHYSICAL",
>     "options" : [ ],
>     "queue" : 0,
>     "resultMode" : "EXEC"
>   },
>   "graph" : [ {
>     "pop" : "parquet-scan",
>     "@id" : 6,
>     "entries" : [ {
>       "path" : "maprfs:/drill/testdata/data-shapes/wide-columns/flat/wide-strings"
>     } ],
>     "storage" : {
>       "type" : "file",
>       "enabled" : true,
>       "connection" : "maprfs:///",
>       "workspaces" : {
>         "root" : {
>           "location" : "/",
>           "writable" : false,
>           "defaultInputFormat" : null
>         },
>         "tmp" : {
>           "location" : "/tmp",
>           "writable" : true,
>           "defaultInputFormat" : "csv"
>         },
>         "drillTestDir" : {
>           "location" : "/drill/testdata/",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirAmplab" : {
>           "location" : "/drill/testdata/amplab",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirInformationSchema" : {
>           "location" : "/drill/testdata/information-schema",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirUdfs" : {
>           "location" : "/drill/testdata/udfs/",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirP1" : {
>           "location" : "/drill/testdata/p1tests",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirTpch10Parquet" : {
>           "location" : "/drill/testdata/tpch10",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "Join" : {
>           "location" : "/drill/testdata/join",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "NoExtJson" : {
>           "location" : "/drill/testdata/no-extension/json",
>           "writable" : true,
>           "defaultInputFormat" : "json"
>         },
>         "NoExtParquet" : {
>           "location" : "/drill/testdata/no-extension/parquet",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "NoExtParquetNull" : {
>           "location" : "/drill/testdata/no-extension/parquet",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "NoExtText" : {
>           "location" : "/drill/testdata/no-extension/text",
>           "writable" : true,
>           "defaultInputFormat" : "psv"
>         },
>         "drillTestDirExchanges" : {
>           "location" : "/drill/testdata/exchanges_test",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "TpcHMulti" : {
>           "location" : "/drill/testdata/tpch-multi",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "TpcHMulti100" : {
>           "location" : "/drill/testdata/SF100",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "TpcHMulti1" : {
>           "location" : "/drill/testdata/tpch_SF1",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirExplicit" : {
>           "location" : "/drill/testdata/explicit_cast",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirImplicit" : {
>           "location" : "/drill/testdata/implicit_cast",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirImplicit1" : {
>           "location" : "/drill/testdata/implicit_cast",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirTPCDS" : {
>           "location" : "/user/root/tpcds/parquet",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "TPCDS" : {
>           "location" : "/drill/testdata/tpcds",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillMondrian" : {
>           "location" : "/user/root/mondrian",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirDatetime" : {
>           "location" : "/drill/testdata/datetime/datasources",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirViews" : {
>           "location" : "/drill/testdata/views/",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirNumerical" : {
>           "location" : "/drill/testdata/numerical/",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "drillTestDirJson" : {
>           "location" : "/drill/testdata/json_storage/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTestNewWS" : {
>           "location" : "/drill/testdata/newWS/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpch01Text" : {
>           "location" : "/drill/testdata/Tpch0.01/text/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpch01Json" : {
>           "location" : "/drill/testdata/Tpch0.01/json/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpch01Parquet" : {
>           "location" : "/drill/testdata/Tpch0.01/parquet/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirConvert" : {
>           "location" : "/drill/testdata/convert",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpch100Text" : {
>           "location" : "/drill/testdata/tpch100/text/",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpch100Parquet" : {
>           "location" : "/drill/testdata/tpch100/parquet",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirAggregate1parquet" : {
>           "location" : "/drill/testdata/tpcds/parquet/s1",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirAggregate1csv" : {
>           "location" : "/drill/testdata/tpcds/csv/s1",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirAggregate1json" : {
>           "location" : "/drill/testdata/tpcds/json/s1",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirMondrian" : {
>           "location" : "/drill/testdata/mondrian",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "drillTestDirTpcdsImpalaSF1" : {
>           "location" : "/drill/testdata/tpcds-impala-sf1",
>           "writable" : true,
>           "defaultInputFormat" : null
>         },
>         "sandbox" : {
>           "location" : "/sandbox",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "sandbox-logs" : {
>           "location" : "/sandbox/flat",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         },
>         "sandbox-json" : {
>           "location" : "/sandbox/json",
>           "writable" : true,
>           "defaultInputFormat" : "parquet"
>         }
>       },
>       "formats" : {
>         "psv" : {
>           "type" : "text",
>           "extensions" : [ "tbl" ],
>           "delimiter" : "|"
>         },
>         "dsv" : {
>           "type" : "text",
>           "extensions" : [ "dat" ],
>           "delimiter" : "|"
>         },
>         "csv" : {
>           "type" : "text",
>           "extensions" : [ "csv" ],
>           "delimiter" : ","
>         },
>         "tsv" : {
>           "type" : "text",
>           "extensions" : [ "tsv" ],
>           "delimiter" : "\t"
>         },
>         "parquet" : {
>           "type" : "parquet"
>         },
>         "json" : {
>           "type" : "json"
>         }
>       }
>     },
>     "format" : {
>       "type" : "parquet"
>     },
>     "columns" : [ "`str_var`", "`tinyint_var`" ],
>     "selectionRoot" : "/drill/testdata/data-shapes/wide-columns/flat/wide-strings",
>     "cost" : 50.0
>   }, {
>     "pop" : "external-sort",
>     "@id" : 5,
>     "child" : 6,
>     "orderings" : [ {
>       "order" : "ASC",
>       "expr" : "`tinyint_var`",
>       "nullDirection" : "UNSPECIFIED"
>     } ],
>     "reverse" : false,
>     "initialAllocation" : 20000000,
>     "maxAllocation" : 10000000000,
>     "cost" : 50.0
>   }, {
>     "pop" : "selection-vector-remover",
>     "@id" : 4,
>     "child" : 5,
>     "initialAllocation" : 1000000,
>     "maxAllocation" : 10000000000,
>     "cost" : 50.0
>   }, {
>     "pop" : "project",
>     "@id" : 3,
>     "exprs" : [ {
>       "ref" : "`tinyint_var`",
>       "expr" : "`tinyint_var`"
>     }, {
>       "ref" : "`$f1`",
>       "expr" : "length(`str_var`) "
>     } ],
>     "child" : 4,
>     "initialAllocation" : 1000000,
>     "maxAllocation" : 10000000000,
>     "cost" : 50.0
>   }, {
>     "pop" : "hash-aggregate",
>     "@id" : 2,
>     "child" : 3,
>     "cardinality" : 1.0,
>     "initialAllocation" : 1000000,
>     "maxAllocation" : 10000000000,
>     "groupByExprs" : [ {
>       "ref" : "`tinyint_var`",
>       "expr" : "`tinyint_var`"
>     } ],
>     "aggrExprs" : [ {
>       "ref" : "`EXPR$0`",
>       "expr" : "max(`$f1`) "
>     } ],
>     "cost" : 25.0
>   }, {
>     "pop" : "project",
>     "@id" : 1,
>     "ex |
> +------------+------------+
> 1 row selected (0.087 seconds)
> {code}
> The sub-query actually does an order by. So when we do a group by, it makes more sense
cost-wise to use the streaming aggregate instead of hash-aggregate.
> I attached the parquet file used. Let me know if you have any questions.



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