More on Partial Indexes to come soon in Part.
If we look at a partial 11g global index block dump after dropping a table partition (eg.
SQL exec tabname 'pink_floyd estimate_percent null, cascade true, method_opt 'FOR ALL columns size 1 FOR columns status size 5 PL/SQL procedure successfully completed.
So its therefore now very quick and very cheap to update these global indexes on the fly.Thats potentially 95 of wasted resources, 95 of wasted effort.The indexing clause determines whether or not the partition is to be indexed.PUT_line alter table 'P_table_name' ADD partition ' V_partition_name ' values less than V_limit execute immediate 'alter table 'P_table_name' ADD partition ' V_partition_name ' values less than V_limit N_counter : N_counter 1; END loop; END; Call this procedure from SQL prompt by passing name of the.Data Conversions When mapping columns, you can convert data types, with some restrictions.I look at a number of different techniques we can use in Part.Elapsed: 00:03:56.52 Execution Plan Plan hash value: Id Operation Name Rows Cost (CPU) Time insert statement 1 2 (0) 00:00:01 1 load table conventional muse 2 count connect BY without filtering 4 fast dual 1 2 (0) 00:00: Predicate Information (identified by operation id filter(level.So how decathlon echange et retour we actually get rid of these orphaned index entries?This time, well create a Local Partial Index: SQL create index pink_floyd_status_i on pink_floyd(status) local indexing partial; Index created.There are lots of great new features introduced with Oracle Database 12c R2, but sometimes its these lesser know features that can so terribly useful.There is one scenario in which the creation of a Partial Index is not permitted, that is in the creation of a Unique Index or a Non-Unique Index to police a Primary Key or Unique Key constraint.SQL select index_name, num_rows,.blocks, leaf_blocks, status, orphaned_entries from dba_indexes i, dba_segments s where dex_name gment_name and table_name'muse index_name NUM_rows blocks leaf_blocks status ORP muse_ID_I valid YES SQL analyze index muse_id_i validate structure; Index analyzed.You can discover if errors occurred while copying dependent objects by checking the num_errors output argument.Wouldnt it be nice if somehow we could get the benefits of performing a FTS (multiblock reads, reading a specific block just the once, etc.) but only read the say 5 of the data that we were actually interested in (or something significantly less than the.So, here is how it all worked out.Basically, when a table partition is dropped/truncated with the update global indexes clause, Oracle simply keeps track of the object numbers of those table partitions and ignores any corresponding rowids within the index during subsequent index scans.The job that been running and loading data just fine, suddenly becomes too slow and becomes a bottleneck.For example, when manually creating a materialized view log on the interim table, you can log different columns.This provides us with the flexibility to say only create partitions with data that would make sense to index, to not index current partitions where perhaps data insert performance is paramount, etc.To illustrate, a simple little demo as usual Firstly, Ill create a partitioned table with the new indexing clause: SQL create table pink_floyd (id number, status varchar2(6 echange steam bug name varchar2(30) indexing OFF partition by range (id) (partition pf1 values less than (1000001 partition pf2 values less.The Cost based Optimizer (CBO) can automatically take advantage of partition pruning and only needs to access the partition or those partitions that only can contain the data of interest.
This in the end means accessing more index blocks, potentially performing more block splits, more newer blocks having to be generated and overall more work having to be performed than would have been necessary if they had just been plain deleted index entries.
It actually makes a lot of sense to do this.