Three questions on Partitioning

Question

11.2.0.3 on Solaris 10
Question 1.
For RANGE partitioning or LIST partitioning or a composite of RANGE and LIST partitioning is it recommended to have global Indexes ?
Question 2.
For the below table we have created an index named IDX_NVH_CRTN_CLT_DTL_P as shown below in the CREATE INDEX statement.
This is called "Local index" because for each table partition an Index segment will be created. Right?
Question 3.
In table's DDL (extracted using Toad) , I can see that the first partition is user defined because of its naming (NVH_CRTN_CLT_DTL_P1 ) . The next partition names seems to system generated names like SYS_ . Why is that ?
-- Table with Range partitioning based on Month_id Column
create table NVH_CRTN_CLT_DTL_P
  month_id                 NUMBER(6),
  client_id                VARCHAR2(400 CHAR),
  client_subprofile_id     NUMBER(15),
  client_mgmt_country_code VARCHAR2(5 CHAR),
  product_area_code        VARCHAR2(25 CHAR),
  rolling_rvn_amt          NUMBER(20,10),
  avg_rwa_amt              NUMBER(20,10),
  group_id                 VARCHAR2(25 CHAR),
  csb_id                   VARCHAR2(400 CHAR),
  nvh_rgn_cde              VARCHAR2(8 CHAR)
partition by range (MONTH_ID)
  partition NVH_CRTN_CLT_DTL_P1 values less than (201101)
    tablespace WMNH_TBS
    pctfree 10
    initrans 1
    maxtrans 255
    storage
      initial 64K
      next 1M
      minextents 1
      maxextents unlimited
  partition SYS_P4592 values less than (201102)
    tablespace WMNH_TBS
    pctfree 10
    initrans 1
    maxtrans 255
    storage
      initial 64K
      next 1M
      minextents 1
      maxextents unlimited
  partition SYS_P4590 values less than (201103)
    tablespace WMNH_TBS
    pctfree 10
    initrans 1
    maxtrans 255
    storage
      initial 64K
      next 1M
      minextents 1
      maxextents unlimited
--- Index is based on MONTH_ID and GROUP_ID columns
create index IDX_NVH_CRTN_CLT_DTL_P on NVH_CRTN_CLT_DTL_P (MONTH_ID, GROUP_ID) local;

Answer 1

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Question 1.
For RANGE partitioning or LIST partitioning or a composite of RANGE and LIST partitioning is it recommended to have global Indexes ?
>
Contrary to previous advice global indexes can be used for all table types, not just RANGE.
You should review the VLDB and Partitioning Guide for information about global and local indexes
http://docs.oracle.com/cd/B28359_01/server.111/b32024/partition.htm
See the Overview of Partitioned Indexes and the Local Partitioned Indexes sections
>
Question 2.
For the below table we have created an index named IDX_NVH_CRTN_CLT_DTL_P as shown below in the CREATE INDEX statement.
This is called "Local index" because for each table partition an Index segment will be created. Right?
>
Yes - this is explained in the Local Partitioned Indexes section I referred to above
>
Local partitioned indexes are easier to manage than other types of partitioned indexes. They also offer greater availability and are common in DSS environments. The reason for this is equipartitioning: each partition of a local index is associated with exactly one partition of the table. This enables Oracle to automatically keep the index partitions in sync with the table partitions, and makes each table-index pair independent. Any actions that make one partition's data invalid or unavailable only affect a single partition.
Local partitioned indexes support more availability when there are partition or subpartition maintenance operations on the table. A type of index called a local nonprefixed index is very useful for historical databases. In this type of index, the partitioning is not on the left prefix of the index columns.
>
Note the 'equipartition' mentioned in the third sentence: one table partition => one index partition
>
Question 3.
In table's DDL (extracted using Toad) , I can see that the first partition is user defined because of its naming (NVH_CRTN_CLT_DTL_P1 ) . The next partition names seems to system generated names like SYS_ . Why is that ?
>
If you create a partitioned table and do not provide names for some or all of the partitions they will be given system-generated names. If you split a partition and don't name the new partition it will also be given a system-generated name.
Odds are that your table was created using code similar to this example
create table NVH_CRTN_CLT_DTL_P
  month_id                 NUMBER(6),
  client_id                VARCHAR2(400 CHAR),
  client_subprofile_id     NUMBER(15),
  client_mgmt_country_code VARCHAR2(5 CHAR),
  product_area_code        VARCHAR2(25 CHAR),
  rolling_rvn_amt          NUMBER(20,10),
  avg_rwa_amt              NUMBER(20,10),
  group_id                 VARCHAR2(25 CHAR),
  csb_id                   VARCHAR2(400 CHAR),
  nvh_rgn_cde              VARCHAR2(8 CHAR)
partition by range (MONTH_ID)
  partition NVH_CRTN_CLT_DTL_P1 values less than (201101),
  partition values less than (201102),
  partition values less than (201103)
)Note that the last two partition clauses do not provide names so, on my system, they were named SYS_P910 and SYS_P911