INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10

CREATE TABLE tab1
(
        dat             DATE,
  ....
        ) FRAGMENT BY     RANGE (dat)
        INTERVAL (INTERVAL (1) DAY (9) TO DAY) STORE IN .....

Query:

SELECT num, dat FROM tab1 WHERE dat=MDY(10,15,2017)  ORDER BY 1

Without PDQ:

  1) hedwigb.tab1: INDEX PATH

        Filters: hedwigb.tab1.dat = 10/15/2017

    (1) Index Name: hedwigb.idx1
        Index Keys: num   (Serial, fragments: 17455)
        Fragments Scanned: (17455) sys_p17455 in p4k005

  Table map :
  ----------------------------
  Internal name     Table name
  ----------------------------
  t1                tab1

  type     table  rows_prod  est_rows  rows_scan  time
est_cost

----------------------------------------------------------------
---
  scan     t1     10000      100000    999999     00:01.86
30047

With PDQ:
  1) hedwigb.tab1: INDEX PATH

        Filters: hedwigb.tab1.dat = 10/15/2017

    (1) Index Name: hedwigb.idx1
        Index Keys: num   (Parallel, fragments: 17455)
        Fragments Scanned: (17455) sys_p17455 in p4k005


Query statistics:
-----------------

  Table map :
  ----------------------------
  Internal name     Table name
  ----------------------------
  t1                tab1

  type     table  rows_prod  est_rows  rows_scan  time
est_cost

----------------------------------------------------------------
---
  scan     t1     10000      100000    10000      00:00.00
30047

Why are all rows scanned (see Query statistics) although the
optimizer already knows that it is sufficient to scan only one
fragment?

****************************************************************
* USERS AFFECTED:                                              *
* Users of IDS 12.10.xC10 and earlier versions.                *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* All rows are read instead of reading only one fragment       *
* without PDQ.                                                 *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************

not known / see Local fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

24.12.2018
08.10.2019
08.10.2019

12.10.xC11