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Posted to issues@trafodion.apache.org by "Selvaganesan Govindarajan (JIRA)" <ji...@apache.org> on 2015/11/19 23:24:11 UTC
[jira] [Commented] (TRAFODION-1638) Transaction should be used even
for select statement in read uncommitted access when it is done within a
transaction
[ https://issues.apache.org/jira/browse/TRAFODION-1638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15014539#comment-15014539 ]
Selvaganesan Govindarajan commented on TRAFODION-1638:
------------------------------------------------------
DDL transaction needs to be enabled for this work correctly in certain scenario where select ..in read uncommitted access and drop on the table is attempted. Hence this change is on hold till DDL transaction is enabled.
> Transaction should be used even for select statement in read uncommitted access when it is done within a transaction
> --------------------------------------------------------------------------------------------------------------------
>
> Key: TRAFODION-1638
> URL: https://issues.apache.org/jira/browse/TRAFODION-1638
> Project: Apache Trafodion
> Issue Type: Bug
> Components: sql-exe
> Affects Versions: 1.0 (pre-incubation)
> Reporter: Selvaganesan Govindarajan
>
> The following test case shows the inserted rows are not shown when select is done with read uncommitted access
> create table tselva (c1 int, c2 int);
> >>begin work ;
> --- SQL operation complete.
> >>insert into tselva values (2,2) ;
> --- 1 row(s) inserted.
> >>select * from tselva ;
> C1 C2
> ----------- -----------
> 1 2
> 2 2
> --- 2 row(s) selected.
> >>get statistics for qid current ;
> Qid MXID11000026567212314627721939132000000000206U3333300_336___SQLCI_DML_LAST__
> Compile Start Time 2015/11/18 17:29:34.154042
> Compile End Time 2015/11/18 17:29:34.154849
> Compile Elapsed Time 0:00:00.000807
> Execute Start Time 2015/11/18 17:29:34.154977
> Execute End Time 2015/11/18 17:29:34.165413
> Execute Elapsed Time 0:00:00.010436
> State DEALLOCATED
> Rows Affected 0
> SQL Error Code 100
> Stats Error Code 0
> Query Type SQL_SELECT_NON_UNIQUE
> Sub Query Type SQL_STMT_NA
> Estimated Accessed Rows 0
> Estimated Used Rows 0
> Parent Qid NONE
> Parent Query System NONE
> Child Qid NONE
> Number of SQL Processes 1
> Number of Cpus 1
> Transaction Id 57357
> Source String select * from tselva ;
> SQL Source Length 22
> Rows Returned 2
> First Row Returned Time 2015/11/18 17:29:34.164801
> Last Error before AQR 0
> Number of AQR retries 0
> Delay before AQR 0
> No. of times reclaimed 0
> Cancel Time -1
> Last Suspend Time -1
> Stats Collection Type OPERATOR_STATS
> SQL Process Busy Time 3,540
> UDR Process Busy Time 0
> SQL Space Allocated 32 KB
> SQL Space Used 5 KB
> SQL Heap Allocated 15 KB
> SQL Heap Used 8 KB
> EID Space Allocated 0 KB
> EID Space Used 0 KB
> EID Heap Allocated 0 KB
> EID Heap Used 0 KB
> Processes Created 0
> Process Create Time 0
> Request Message Count 0
> Request Message Bytes 0
> Reply Message Count 0
> Reply Message Bytes 0
> Scr. Overflow Mode UNKNOWN
> Scr File Count 0
> Scr. Buffer Blk Size 0
> Scr. Buffer Blks Read 0
> Scr. Buffer Blks Written 0
> Scr. Read Count 0
> Scr. Write Count 0
> Table Name
> Records Accessed Records Used HBase/Hive HBase/Hive HBase/Hive IO HBase/Hive IO
> Estimated/Actual Estimated/Actual IOs IO MBytes Sum Time Max Time
> TRAFODION.SCH.TSELVA
> 0 100
> 2 2 2 0 8,789 8,789
> --- SQL operation complete.
> >>fc sele
> >>select * from tselva ;
> .. ifor read uncommitted access ;
> >>select * from tselva for read uncommitted access ;;
> ..
> C1 C2
> ----------- -----------
> 1 2
> --- 1 row(s) selected.
> Row is missing though executed under the same transaction
> >>fc get statistics
> >>get statistics for qid current ;
> ..
> Qid MXID11000026567212314627721939132000000000206U3333300_338___SQLCI_DML_LAST__
> Compile Start Time 2015/11/18 17:30:04.043650
> Compile End Time 2015/11/18 17:30:04.051613
> Compile Elapsed Time 0:00:00.007963
> Execute Start Time 2015/11/18 17:30:04.051768
> Execute End Time 2015/11/18 17:30:04.061414
> Execute Elapsed Time 0:00:00.009646
> State DEALLOCATED
> Rows Affected 0
> SQL Error Code 100
> Stats Error Code 0
> Query Type SQL_SELECT_NON_UNIQUE
> Sub Query Type SQL_STMT_NA
> Estimated Accessed Rows 0
> Estimated Used Rows 0
> Parent Qid NONE
> Parent Query System NONE
> Child Qid NONE
> Number of SQL Processes 1
> Number of Cpus 1
> Transaction Id 57357
> Source String select * from tselva for read uncommitted access ;
> SQL Source Length 50
> Rows Returned 1
> First Row Returned Time 2015/11/18 17:30:04.060778
> Last Error before AQR 0
> Number of AQR retries 0
> Delay before AQR 0
> No. of times reclaimed 0
> Cancel Time -1
> Last Suspend Time -1
> Stats Collection Type OPERATOR_STATS
> SQL Process Busy Time 3,935
> UDR Process Busy Time 0
> SQL Space Allocated 32 KB
> SQL Space Used 5 KB
> SQL Heap Allocated 15 KB
> SQL Heap Used 8 KB
> EID Space Allocated 0 KB
> EID Space Used 0 KB
> EID Heap Allocated 0 KB
> EID Heap Used 0 KB
> Processes Created 0
> Process Create Time 0
> Request Message Count 0
> Request Message Bytes 0
> Reply Message Count 0
> Reply Message Bytes 0
> Scr. Overflow Mode UNKNOWN
> Scr File Count 0
> Scr. Buffer Blk Size 0
> Scr. Buffer Blks Read 0
> Scr. Buffer Blks Written 0
> Scr. Read Count 0
> Scr. Write Count 0
> Table Name
> Records Accessed Records Used HBase/Hive HBase/Hive HBase/Hive IO HBase/Hive IO
> Estimated/Actual Estimated/Actual IOs IO MBytes Sum Time Max Time
> TRAFODION.SCH.TSELVA
> 0 100
> 1 1 2 0 7,725 7,725
> --- SQL operation complete.
> >>
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