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Performance problem in 7.6.6.10

We have a performance problem after doing the update from MaxDB 7.6.6.3 to 7.6.6.10.

The symptom is that querys with the "<>" operator in the WHERE-Clause on a indexed Integer/SmallInteger-column slows down extremly, e.g. "WHERE FILEDNAME <> 1".

On large tables the query is very, very slow.

The dbanalyser shows "DIFFERENT STRATEGIES FOR OR-TERMS".

A way to reproduce the prob:

Create a table with 2 columns

-


CREATE TABLE "ADMIN"."TEST"

(

"INTID" Integer NOT NULL,

"FLAG" Smallint,

PRIMARY KEY("INTID")

)

Index on Column FLAG

-


CREATE INDEX "IDX_TEST" ON "ADMIN"."TEST"("FLAG" ASC)

Insert about 1000 lines in the TEST

-


INSERT INTO TEST (SELECT ROWNO, 1 FROM LARGETABLE WHERE ROWNO <= 1000)

(The easiest way for me to fill the table.)

Call the dbanalyser

-


EXPLAIN SELECT * FROM TEST WHERE FLAG <> 1

OWNER TABLENAME COLUMN_OR_INDEX STRATEGY PAGECOUNT

ADMIN TEST DIFFERENT STRATEGIES FOR OR-TERMS 8

IDX_TEST RANGE CONDITION FOR INDEX

ONLY INDEX ACCESSED

FLAG (USED INDEX COLUMN)

IDX_TEST RANGE CONDITION FOR INDEX

ONLY INDEX ACCESSED

FLAG (USED INDEX COLUMN)

RESULT IS COPIED , COSTVALUE IS 6

QUERYREWRITE - APPLIED RULES:

DistinctPullUp 1

The statement is fast because of the small table, but I think the startegy is wrong.

Former Member
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