IT18223: QUERY THAT USED TO RUN FINE IN 11.50 NOW ALLOCATES SO MUCH MEMORY THAT THE INSTANCE RUNS OUT

APAR status

• Closed as program error.

Error description

• When running a version of IDS that has the fix for APAR IT17068,
  a large query allocates huge amounts of memory:
  
  Memory pools    count 2
  name         class addr              totalsize  freesize
  #allocfrag
  #freefrag
  143          V     12cf0d040        4122255360 86936      252812
  61
  ...
  
  ...consisting mainly of ralloc memory:
  
  name           free       used
  ralloc         0          4121483264
  
  ...until the server runs out of memory and returns -208 to the
  client.  The "onstat -g afr <session>" output shows these
  allocations over and over:
  
  addr             size       memid        fileid location
  ...
  15479b000        16384      ralloc       4341   sqhash.c:1379
  ...
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of 12.10.xC1 through 12.10.xC8.                        *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * A query may require large amount of memory (RALLOC memory)   *
  * under the following conditions:                              *
  *   - query contains GROUP BY clause                           *
  *   - there are large number of GROUP BY columns (e.g. > 10)   *
  *   - at least one of the GROUP BY columns is of type LVARCHAR *
  *   - query produces large number of rows for the GROUP BY     *
  * operation (e.g., > 40 K)                                     *
  *   - there is also a large number of resulting groups (e.g. > *
  * 20 K)                                                        *
  *   - PDQ is not on, and DS_NONPDQ_QUERY_MEM is either not     *
  * configured or configured to a small amount (e.g. 256)        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IBM Informix Server 12.10.xC9                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IBM Informix Server 12.10.xC9
  

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

• RC10 PSN

     UP