Справочник Пользователя для Oracle Audio Technologies B10508-01
Suggested Parameter Settings
Oracle9i 64-bit Feature
B-3
sections that are not backed by any file
.
These global sections are not pageable and
do not require a backing file.
Suggested Parameter Settings
1.
Big Oracle Blocks (BOB) provide the ability to support larger I/O transfers
between memory and disk
between memory and disk
.
BOB complements large SGA configurations,
because BOB allows the system to move data faster between memory and disk
.
With VLM configurations, system performance depends directly on the ability
of the system to move database blocks into the SGA as efficiently as possible
of the system to move database blocks into the SGA as efficiently as possible
.
Without the benefits of improved data transfer, performance can decline.
For a pure decision support system (DSS) application, you may wish to choose
a large value (such as 32K) for DB_BLOCK_SIZE
a large value (such as 32K) for DB_BLOCK_SIZE
.
For an OLTP type of
application, choose a lower value (such as, 2K or 4K)
.
The larger the DB_
BLOCK_SIZE, the more serious the impact on single-row lookups.
2.
Configure the size of the Oracle buffer cache such that it will provide the best
possible cache hit ratio without affecting memory requirements of other Oracle
and system processes.
possible cache hit ratio without affecting memory requirements of other Oracle
and system processes.
For example, for a 3 GB buffer cache, with DB_BLOCK_SIZE=8192, set DB_
BLOCK_BUFFERS=400000.
BLOCK_BUFFERS=400000.
3.
To enable Cost Based Optimizer (CBO), set:
optimizer_mode = choose
To use CBO, make sure all the tables and indexes are analyzed so that the
statistics are up-to-date
statistics are up-to-date
.
Use the SQL*Plus commands "analyze ...estimate" for
large tables and "analyze index ... compute statistics" for indexes.
4.
Set the SORT_AREA_SIZE parameter with care
.
SORT_AREA_SIZE is the
space used in Program Global Area (PGA) for each sort executed by each Oracle
process
process
.
If the value is too high, the PGA will use excessive memory when
sorting
.
The default value (512 K) is usually sufficient.
Note:
When no statistics are gathered or available, the Rule-based
Optimizer (RBO) is used.
Note:
Ensure the query does not use the rule hint (/*+ rule */)
.
Otherwise the CBO will be disabled.