IT10384: WITH AN LBAC PROTECTED TABLE SPL WHERE CLAUSE USING VARIABLE PARAMETER WILL TAKE SEQUENTIAL SCAN

APAR status

• Closed as program error.

Error description

• In SPL, a query like this, on an LBAC protected table, will
  yield an index access as expected:
  
   select col2 into ret from my_tab where col1=10000;
  
    1) informix.lbac_tab: INDEX PATH
  
          Filters: LBACEnforceRow(informix.lbac_tab.lbl )
  
      (1) Index Name: andreasl.idx_lbac_tab_col1
          Index Keys: col1   (Serial, fragments: ALL)
          Lower Index Filter: informix.lbac_tab.col1 = 10000
  
  
  whereas the same query using a variable parameter instead of
  literal would take a sequential scan path:
  
   let l_id = 10000;
   select col2 into ret from my_tab where col1=l_id;
  
    1) informix.lbac_tab: SEQUENTIAL SCAN  (Serial, fragments:
  ALL)
  
          Filters: (LBACEnforceRow(informix.lbac_tab.lbl ) AND
  informix.lbac_tab.col1 = '<VAR>' )
  
  
  Even when forcing index access, this index would be read
  sequentially:
  
   let l_id = 10000;
   select {+INDEX(lbac_tab idx_lbac_tab_id)} col2 into ret from
  my_tab where col1=l_id;
  
  
    1) informix.lbac_tab: INDEX PATH
  
          Filters: (LBACEnforceRow(informix.lbac_tab.lbl ) AND
  informix.lbac_tab.col1 = '<VAR>' )
  
      (1) Index Name: andreasl.idx_lbac_tab_col1
          Index Keys: col1   (Serial, fragments: ALL)
  
  
  Explicitely updating statistics, or re-creating the index, would
  even make the second SPL (parametrized statement) fail with:
  
    768: Internal error in routine lbac_chk_idx_fltrs: unsafe
  filter in index scan.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users                                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IBM Informix Server 12.10.xC6                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IBM Informix Server 12.10.xC6
  

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

• RA10 PSN

     UP

• RA10 PSY

     UP

• RB10 PSN

     UP

• RB10 PSY

     UP

• RB50 PSN

     UP

• RB50 PSY

     UP

• RB70 PSN

     UP

• RB70 PSY

     UP

• RC10 PSN

     UP

• RC10 PSY

     UP