JR30649: READERS-PER-NODE AND FILTER OPTION ON SEQUENTIAL STAGE SHOULD BE MUTUALLY EXCLUSIVE

APAR status

• Closed as program error.

Error description

• The filter option should really be made mutually exclusive with
  multiple readers as in most situations it will not function as
  desired.
  
  The problem will occur with any filter that causes the number of
  bytes read to be different (in this case less) than the number
  of bytes in the record.  The reason for this is the way that the
  multiple readers functionality works.  In the case of a
  delimited file it is split up based on its total byte length.
  Taking a simple case where the file length is 256 and we have 2
  readers, reader 1 will be set to read from byte 0 to 128 and
  reader 2 from 128 to 256.  Now it is very likely byte 128 falls
  in the middle of a record.  In this case reader 1 will read from
  0 to 128 plus the number of bytes to the next record delim.
  Reader 2 will start reading at byte 128 until it finds the first
  record delim and ignore this data, starting actual reading at
  the next record.  This guarantees there is no overlap and the
  correct number of records is read.
  Sequential file stage using multiple readers and filter option:
  example:
  -readers 2
  -filter 'cut -c1-4'
  
  The problem occurs when the first reader is calculating its
  current offset.  Since the filter is passing fewer bytes than
  are actually in the file, the first reader will calculate its
  offset to be earlier in the file than it actually is meaning it
  will read a bunch of records past where it is supposed to stop.
  
  Unfortunately the solution to this would mean preprocessing the
  file which would negate any performance improvements of running
  multiple readers on the file.
  
  The answer to this is this combination of
  arguments is not supported and should be flagged as such.
  

Local fix

• do not use filter and multiple node option together
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All versions of IS
  ****************************************************************
  PROBLEM DESCRIPTION:
  When the filter and readers options are used in conjunction the
  results are only correct under certain situations.  The user is
  not made aware of that.
  ****************************************************************
  RECOMMENDATION:
  Install patch JR30649
  This change is included in 8.1 Fix Pack 1.
  ****************************************************************
  

Problem conclusion

• A warning was added to alert the user to the possibility of
  improper function in 8.0.1 and beyond.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Modules/Macros

• SERVER
  

Fix information

• Fixed component name

  WIS DATASTAGE

• Fixed component ID

  5724Q36DS

Applicable component levels

• R752 PSN

     UP