Query Performance and reading an Explain Plan

Question

Hi,
Below I have posted a query that is running slowly for me - upwards of 10 minutes which I would not expect. I have also supplied the explain plan. I'm fairly new to explain plans and not sure what the danger signs are that I should be looking out for.
I have added indexes to these tables, a lot of which are used in the JOIN and so I expected this to be quicker.
Any help or pointers in the right direction would be very much appreciated -
SELECT a.lot_id, a.route, a.route_rev
FROM wlos_owner.tbl_current_lot_status_dim a, wlos_owner.tbl_last_seq_num b, wlos_owner.tbl_hist_metrics_at_op_lkp c
WHERE a.fw_ver = '2'
AND a.route = b.route
AND a.route_rev = b.route_rev
AND a.fw_ver = b.fw_ver
AND a.route = c.route
AND a.route_rev = c.route_rev
AND a.fw_ver = c.fw_ver
AND a.prod = c.prod
AND a.lot_type = c.lot_type
AND c.step_seq_num >= a.step_seq_num
PLAN_TABLE_OUTPUT
Plan hash value: 2447083104
| Id  | Operation           | Name                       | Rows  | Bytes | Cost
(%CPU)| Time     |
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT    |                            |   333 | 33633 |  1347
   (8)| 00:00:17 |
|*  1 |  HASH JOIN          |                            |   333 | 33633 |  1347
   (8)| 00:00:17 |
|*  2 |   HASH JOIN         |                            |   561 | 46002 |  1333
   (7)| 00:00:17 |
|*  3 |    TABLE ACCESS FULL| TBL_CURRENT_LOT_STATUS_DIM | 11782 |   517K|   203
   (5)| 00:00:03 |
PLAN_TABLE_OUTPUT
|*  4 |    TABLE ACCESS FULL| TBL_HIST_METRICS_AT_OP_LKP |   178K|  6455K|  1120
   (7)| 00:00:14 |
|*  5 |   TABLE ACCESS FULL | TBL_LAST_SEQ_NUM           |  8301 |   154K|    13
  (16)| 00:00:01 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   1 - access("A"."ROUTE"="B"."ROUTE" AND "A"."ROUTE_REV"="B"."ROUTE_REV" AND
              "A"."FW_VER"=TO_NUMBER("B"."FW_VER"))
   2 - access("A"."ROUTE"="C"."ROUTE" AND "A"."ROUTE_REV"="C"."ROUTE_REV" AND
              "A"."FW_VER"="C"."FW_VER" AND "A"."PROD"="C"."PROD" AND "A"."LOT_T
YPE"="C"."LOT_TYPE")
       filter("C"."STEP_SEQ_NUM">="A"."STEP_SEQ_NUM")
   3 - filter("A"."FW_VER"=2)
PLAN_TABLE_OUTPUT
   4 - filter("C"."FW_VER"=2)
   5 - filter(TO_NUMBER("B"."FW_VER")=2)
24 rows selected.

Answer 1

Guys thank you for your help.
I changed the type of the offending column and the plan looks a lot better and results seem a lot quicker.
However I have added to my SELECT, quite substantially, and have a new explain plan.
There are two sections in particular that have a high cost and I was wondering if you seen anything inherently wrong or can explain more fully what the PLAN_TABLE_OUTPUT descriptions are telling me - in particular
INDEX FULL SCAN
PLAN_TABLE_OUTPUT
Plan hash value: 3665357134
| Id  | Operation                        | Name                           | Rows
  | Bytes | Cost (%CPU)| Time     |
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT                 |                                |
4 |   316 |    52   (2)| 00:00:01 |
|*  1 |  VIEW                            |                                |
4 |   316 |    52   (2)| 00:00:01 |
|   2 |   WINDOW SORT                    |                                |
4 |   600 |    52   (2)| 00:00:01 |
|*  3 |    TABLE ACCESS BY INDEX ROWID   | TBL_HIST_METRICS_AT_OP_LKP     |
1 |    71 |     1   (0)| 00:00:01 |
PLAN_TABLE_OUTPUT
|   4 |     NESTED LOOPS                 |                                |
4 |   600 |    51   (0)| 00:00:01 |
|   5 |      NESTED LOOPS                |                                |    7
5 |  5925 |    32   (0)| 00:00:01 |
|*  6 |       INDEX FULL SCAN            | UNIQUE_LAST_SEQ                |    8
9 |  2492 |    10   (0)| 00:00:01 |
|   7 |       TABLE ACCESS BY INDEX ROWID| TBL_CURRENT_LOT_STATUS_DIM     |
PLAN_TABLE_OUTPUT
1 |    51 |     1   (0)| 00:00:01 |
|*  8 |        INDEX RANGE SCAN          | TBL_CUR_LOT_STATUS_DIM_IDX1    |
1 |       |     1   (0)| 00:00:01 |
|*  9 |      INDEX RANGE SCAN            | TBL_HIST_METRIC_AT_OP_LKP_IDX1 |    2
9 |       |     1   (0)| 00:00:01 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   1 - filter("SEQ"=1)
   3 - filter("C"."FW_VER"=2 AND "A"."PROD"="C"."PROD" AND "A"."LOT_TYPE"="C"."L
OT_TYPE" AND
              "C"."STEP_SEQ_NUM">="A"."STEP_SEQ_NUM")
   6 - access("B"."FW_VER"=2)
       filter("B"."FW_VER"=2)
PLAN_TABLE_OUTPUT
   8 - access("A"."ROUTE"="B"."ROUTE" AND "A"."ROUTE_REV"="B"."ROUTE_REV" AND "A
"."FW_VER"=2)
   9 - access("A"."ROUTE"="C"."ROUTE" AND "A"."ROUTE_REV"="C"."ROUTE_REV")