7.7.07.x: TaskType "JoinInS" - what is it?

[Former Member]

BI (oh, sorry, it's now BW again...) 7.01 on MaxDB 7.7.07.x.

While executing a query I see

ID   UKT UNIX   TASK       APPL Current         Timeout Region     Wait 
          tid   type        pid state          priority cnt try    item 
T108   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
T109   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
T113   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
T114   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
T116   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
T117   4     28 JoinInS         InvSelSrv(070)        0 0               20511567(s)
<...>
T295  14     38 User     21574* IO Wait (R)           0 0     57        15467914(s)

Is that the parallel join option? No problem, just curious....

Markus

[lbreddemann · Accepted solution]

Hi Markus,

yes, these are server tasks doing a parallel join via an index.

As you may know, the server tasks are used much more often from 7.7 onwards - here's a list of examples:

Show Name       Long name                     Description
"DropAux"  "Drop Auxiliary Files"             Performs Drop Table in background
"PrefObj"  "Prefetch Objects"                 Prefetch liveCache objects after restart
"CrIndex"  "Create Index"                     Parallel Create Index
"ChkData"  "Check Data"                       Checks a B*Tree
"BUPvol "  "Backup / Restore Volume Task"     Reads/Writes from/to data volumes for backup
"BUPmed "  "Backup / Restore Medium Task"     Reads/Writes from/to a data backup mediumu201C 
"AutoLgW"  "Autosave Log Reader"              Reads Log pages from the log volumes
"AutoLgW"  "Autosave Log Writer"              Writes Log pages to the backup medium
"PrefOCo"  "Prefetch Objects Coordinator"
"PrefPag"  "Prefetch Pages"
"PrefSel"  "Prefetch Select"                  Prefetching records when scanning
"PrefBlb"  "Prefetch Blob"                    Prefetch of BLOB when returning last part to appl.
"UpdCnt"   "Update Counter"                   Scans tables to read counters.
"DropVol"  "Drop Volume"                      Drops a volume
"UpdStat"  "Update Statistics"                Perform parallel update statistics
"JoinInS"  "Join Index Select"                Perform parallel join via index
"Savepnt"  "Savepoint Coordinator"            Coordinates the phases of a savepoint
"StdbySy"  "Standby Synchronize Server"       Waits for sync calls from a Hot Standby master
"StdbyRC"  "Standby Restart Coordinator"      Coordinates a takeover in a Hot Standby system
"RedoExe"  "RedoLog Execution Task"           Executes redo of log entries
"RedoRea"  "RedoLog Reader"                   Reads from log volume or log file during restore

as usual: this is in no way an official documentation and subject to change...

regards,

Lars

[markus_doehr2 · Accepted solution]

Hey Lars,

thank you for this list. I hope at some point it will be documented (somewhere) officially

Markus

[lbreddemann · Accepted solution]

> thank you for this list. I hope at some point it will be documented (somewhere) officially

I already asked my colleague who took the effort to add all the x_cons pages to the SDN Wiki and she promised to add such a list.

So, it's on its way already (thanks to Gyounghwa Kim@SAP Korea for that much work!).

regards,

Lars