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From Andries Engelbrecht <aengelbre...@maprtech.com>
Subject Re: more on parsing timestamps
Date Thu, 02 Apr 2015 20:36:24 GMT
Cool, thx for testing. 

Best to file a JIRA.

—Andries

On Apr 2, 2015, at 1:27 PM, Sudhakar Thota <sthota@maprtech.com> wrote:

> Vince/Andries,
> 
> Perhaps this could be a bug. I get the same results. 
> 
> But the plan is very different, the UnionExchange is set up immediately after the scan
operation in successful case( Case -1 ), where as UnionExchange is happening after scan->project
(Case -2).
> 
> Case -1.Successful case.
> 
> 0: jdbc:drill:> explain plan for select to_timestamp(t.t, 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''')
FROM (select * from dfs.sthota_prq.`/tstamp_test/*.parquet` limit 13015351) t;
> +------------+------------+
> |    text    |    json    |
> +------------+------------+
> | 00-00    Screen
> 00-01      Project(EXPR$0=[TO_TIMESTAMP(ITEM($0, 't'), 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''')])
> 00-02        SelectionVectorRemover
> 00-03          Limit(fetch=[13015351])
> 00-04            UnionExchange
> 01-01              Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_2_0.parquet],
ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_1_0.parquet],
ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_0_0.parquet]],
selectionRoot=/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test, numFiles=3, columns=[`*`]]])
> | {
>  "head" : {
>    "version" : 1,
>    "generator" : {
>      "type" : "ExplainHandler",
>      "info" : ""
>    },
>    "type" : "APACHE_DRILL_PHYSICAL",
>    "options" : [ ],
>    "queue" : 0,
>    "resultMode" : "EXEC"
>  },
> 
> Case -2. Unsuccessful case:
> 
> 0: jdbc:drill:> explain plan for select to_timestamp(t.t, 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''')
FROM (select * from dfs.sthota_prq.`/tstamp_test/*.parquet` ) t;
> +------------+------------+
> |    text    |    json    |
> +------------+------------+
> | 00-00    Screen
> 00-01      UnionExchange
> 01-01        Project(EXPR$0=[TO_TIMESTAMP(ITEM($0, 't'), 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''')])
> 01-02          Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_2_0.parquet],
ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_1_0.parquet],
ReadEntryWithPath [path=maprfs:/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test/1_0_0.parquet]],
selectionRoot=/mapr/demo.mapr.com/user/sthota/parquet/tstamp_test, numFiles=3, columns=[`*`]]])
> | {
>  "head" : {
>    "version" : 1,
>    "generator" : {
>      "type" : "ExplainHandler",
>      "info" : ""
>    },
>    "type" : "APACHE_DRILL_PHYSICAL",
>    "options" : [ ],
>    "queue" : 0,
>    "resultMode" : "EXEC"
>  },
> 
> Thanks
> Sudhakar Thota
> 
> 
> On Apr 2, 2015, at 12:01 PM, Vince Gonzalez <vince.gonzalez@gmail.com> wrote:
> 
>> Ok, will do. Thanks.
>> 
>> On Thu, Apr 2, 2015 at 2:49 PM, Andries Engelbrecht <
>> aengelbrecht@maprtech.com> wrote:
>> 
>>> Compare the query plans and you probably want to look at the log file to
>>> see what fails and post here.
>>> 
>>> 
>>> 
>>> —Andries
>>> 
>>> 
>>> On Apr 1, 2015, at 12:54 PM, Vince Gonzalez <vince.gonzalez@gmail.com>
>>> wrote:
>>> 
>>>> Is this a bug?
>>>> 
>>>> Created a parquet table (using CTAS) with one column containing text
>>>> timestamps.
>>>> 
>>>> 0: jdbc:drill:zk=localhost:2181> select * from tstamp_test limit 1;
>>>> +------------+
>>>> |     t      |
>>>> +------------+
>>>> | 2015-01-27T13:43:53.000Z |
>>>> +------------+
>>>> 1 row selected (0.119 seconds)
>>>> 
>>>> The below queries, identical apart from the limit clause, behave
>>>> differently. The one with the limit clause works, the one without
>>> doesn't.
>>>> The limit is larger than the total number of rows, so in both cases we
>>>> should be processing all rows.
>>>> 
>>>> No limit clause. It fails:
>>>> 
>>>> ```
>>>> 0: jdbc:drill:zk=localhost:2181> select to_timestamp(t.t,
>>>> 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''') FROM (select t from tstamp_test) as
>>> t;
>>>> Query failed: RemoteRpcException: Failure while trying to start remote
>>>> fragment, Expression has syntax error! line 1:30:mismatched input 'T'
>>>> expecting CParen [ 7d30d753-0822-4820-afd0-b7e7fe5e639c on
>>>> 192.168.99.1:31010 ]
>>>> ```
>>>> 
>>>> Limit clause in the subselect (larger than the number of rows in the
>>> table)
>>>> succeeds.
>>>> 
>>>> ```
>>>> 0: jdbc:drill:zk=localhost:2181> select to_timestamp(t.t,
>>>> 'YYYY-MM-dd''T''HH:mm:ss.SSS''Z''') FROM (select t from tstamp_test limit
>>>> 100000000) as t;
>>>> ...
>>>> | 2015-02-17 07:18:00.0 |
>>>> +------------+
>>>> 13,015,350 rows selected (105.257 seconds)
>>>> ```
>>>> 
>>>> Data can be downloaded here:
>>>> 
>>>> https://s3.amazonaws.com/vgonzalez/data/tstamp_test.tar.gz
>>> 
>>> 
> 


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