Hi,
I faced a situation where while querying data from view based on mview does not use index but when we query from mview it uses index and give fast results.
Following are the details:
querying from view: (completes in more than a minute even after passing hint)
================================
explain plan for select /*+ index( ITGI_CREDITOR_LEDGER_CMV ITGI_CREDITOR_LEDGER_INDX) */ * from CR_LEDGER_REP_V where vendor_id='1474911';
Plan hash value: 463951623
---------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 9056K| 5648M| 97644 (1)| 00:00:04 |
|* 1 | VIEW | CR_LEDGER_REP_V | 9056K| 5648M| 97644 (1)| 00:00:04 |
| 2 | COUNT | | | | | |
| 3 | MAT_VIEW ACCESS FULL| ITGI_CREDITOR_LEDGER_CMV | 9056K| 2159M| 97644 (1)| 00:00:04 |
---------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("VENDOR_ID"=1474911)
Querying from mview: (completes within a second)
==============================
explain plan for select /*+ index( ITGI_CREDITOR_LEDGER_CMV ITGI_CREDITOR_LEDGER_INDX) */ * from ITGI_CREDITOR_LEDGER_CMV where vendor_id='1474911';
Plan hash value: 1726512073
--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 21 | 5880 | 21 (0)| 00:00:01 |
| 1 | MAT_VIEW ACCESS BY INDEX ROWID BATCHED| ITGI_CREDITOR_LEDGER_CMV | 21 | 5880 | 21 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | ITGI_CREDITOR_LEDGER_INDX | 22 | | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("VENDOR_ID"=1474911)
View DDL
========================
CREATE OR REPLACE FORCE VIEW SANJAY.CR_LEDGER_REP_V
(
QRY,
SR_NO,
VENDOR_ID,
VENDOR_TYPE,
VENDOR_NUMBER,
VENDOR_NAME,
VENDOR_SITE_ID,
VENDOR_SITE_CODE,
GL_DATE,
ACCOUNTING_DATE,
PO,
INVOICE_TYPE,
AP_INVOICE_NO,
INVOICE_DOC_CAT,
AP_INVOICE_DATE,
INVOICE_VOUCHER_NO,
PAYMENT_VOUCHER_NO,
CHQ_NO,
DESCRIPTION,
PAYMENT_DATE,
ACC_CODE,
PAYMENT_METHOD,
CURR_CODE,
DEBIT,
CREDIT
)
AS
SELECT qry,
ROWNUM srn,
vendor_id,
vendor_type_lookup_code,
vendor_no,
vendor_name,
vendor_site_id,
vendor_site_code,
gl_date,
accounting_date,
po_distribution_id,
invoice_type_lookup_code,
invoice_num,
doc_category_code,
invoice_date,
inv_voucher_num,
payment_num,
check_number,
description,
pay_accounting_date,
account_code,
payment_method_code,
invoice_currency_code,
debit,
credit
FROM sanjay.itgi_creditor_ledger_cmv;
Even if I don't use the hints the plan doesn't change.
Though I have told developer to use mview directly, but I could not understand this behaviour.
DB version : 12.1
OS : AIX 6.1
Regards,
Gaurav