Good day,
I am trying to find the technical reason for why Oracle cannot use parallel
slaves to build a single-column index on a sparse column with few distinct
values:
F COUNT(*)
- ----------
538937561
Y 51464
N 17486819
Just by playing around, I discovered that if I put this column as the
leading edge on an index with many columns, it can be built in parallel.
According to the relevant documentation
<http://docs.oracle.com/cd/E11882_01/server.112/e25523/parallel007.htm#i1009131>,
I would expect that the base table is sampled, but perhaps the random
sampling returns 0 keys due to the sparse nature of the column?
Facts:
Oracle Enterprise Edition 11.2.0.4
table is partitioned, but not on this key (lol)
parallel_max_servers=3600
ddl extracted via datapump:
CREATE INDEX "FIMSMGR"."FGBTRND_ENCD_INDEX" ON "FIMSMGR"."FGBTRND"
("FGBTRND_DEFER_GRANT_IND")
PCTFREE 10 INITRANS 2 MAXTRANS 255
STORAGE(INITIAL 5242880 NEXT 5242880 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "FIN_LARGE_INDX" PARALLEL 100 ;
--
Charles Schultz
