IT35674: DBIMPORT OF TABLE WITH TEXT/BYTE COLUMN USES A LOT OF SYSTEM TIME DUE TO LOCATING THE BLOB VARIABLE IN FILE

APAR status

• Closed as program error.

Error description

• If you strace the dbimport process while it's working on a table
  with a text/byte column you can see it repeat the following
  pattern of system calls, per row inserted into the table:
  
  
  20:33:42.726326 open("/tmp/dbx21339_5",
  O_WRONLY|O_CREAT|O_TRUNC, 0666) = 12 <0.008205>
  20:33:42.734611 fstat(12, {st_mode=S_IFREG|0664, st_size=0,
  ...}) = 0 <0.000025>
  20:33:42.734733 mmap(NULL, 4096, PROT_READ|PROT_WRITE,
  MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc16119d000 <0.000026>
  20:33:42.734834 write(12, "XXXXXXXXXXXXXXXXXXXXXXX "..., 304) =
  304 <0.000035>
  20:33:42.734915 close(12)               = 0 <0.000078>
  20:33:42.735082 munmap(0x7fc16119d000, 4096) = 0 <0.000035>
  20:33:42.735190 getuid()                = 1500 <0.000028>
  20:33:42.735252 getgid()                = 1500 <0.000020>
  20:33:42.735314 geteuid()               = 1500 <0.000031>
  20:33:42.735386 open("/tmp/dbx21339_5", O_RDONLY) = 12
  <0.000035>
  20:33:42.735475 fcntl(12, F_SETFD, FD_CLOEXEC) = 0 <0.000029>
  20:33:42.735556 sendto(10,
  "\0\4\0\0\0\21\0\0\0o\0\0010M=\263TSXZ0000474044\307\24"...,
  124, 0, NULL, 0) = 124 <0.000071>
  20:33:42.735696 read(12, "XXXXXXXXXXXXXXXXX "..., 304) = 304
  <0.000029>
  20:33:42.735770 read(12, "", 0)         = 0 <0.000022>
  20:33:42.735829 close(12)               = 0 <0.000023>
  20:33:42.735890 sendto(10, "\0'\0010XXXXXXXXXXXXXXX"..., 314, 0,
  NULL, 0) = 314 <0.000032>
  20:33:42.735970 recvfrom(10,
  "\0^\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\17\0\20\0\0\0\1\0\0\0
  \0"..., 4096, 0, NULL, NULL) = 48 <0.000233>
  
  I then did the following performance test using 2 different
  versions of an esql/c client, and dbimport to load a single 2
  column table, an integer and text field.  The timings were with
  the table created as raw (so no logging) and ~115 million rows.
  
  esql/c version 1: 4 hours
  esql/c version 2: 4 hours 40 minutes
  dbimport : 17 hours 30 minutes
  
  Esql/c version 1 generated all the data in memory (so didn't
  read from an .unl file and located the text field using
  LOCMEMORY.  Esql/c version 2 read from a dbexport .unl file and
  parsed the 2 fields for host variables but then located the blob
  host variable also using LOCMEMORY.  Dbimport technically uses
  LOCUSER but it appears we've set that up to essentially behave
  as if LOCFILE was used.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of Informix Server prior to 14.10.xC7.                 *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Informix Server 14.10.xC7.                        *
  ****************************************************************
  

Problem conclusion

• Fixed in Informix Server 14.10.xC7.
  

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:

Fix information

• Fixed component name

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels