Oracle Query Large Table Performance

What are some things i can do to improve query performance of an oracle query without creating indexes.

Oracle query large table performance. Changing the selected columns is of course a change to the query and hence the optimizer may come up with a different means to run it eg sql create table t as select from dba objects. Partitioning can also improve the performance of multi table joins by using a technique known as partition wise joins. Partition wise joins can be applied when two tables are being joined and both tables are partitioned on the join key or when a reference partitioned table is joined with its parent table. I have a critical performance issue due to the large volume of data for a specific customer in a table.

In the upper reaches of the table the queries take quite a while to return over a minute. Whenever that customer s data is fetched the query takes about half an hour to execute whereas it fetches the data in seconds for the other customers. For the sake of completeness to the question how to improve performance on a large table for ad hoc queries it should be noted that while it will not help for this specific case if someone is using sql server 2012 or newer when that time comes and if the table is not being updated then using columnstore indexes is an option. The table s data is displayed in pages to the user.

And that is mostly true when accessing multiple bitmap indexes on the same table. We have a large table 9 million rows that can be searched and sorted at will from a variety of criteria and columns. I may be the millionth customer trying to retrieve data from the same table at the same time the traditional way of table tuning partitioning indexing separate tablespace datafiles for index and table partition level indexing sub partitioning also considering the statistics are not stale does not look like of much help rather i would say the amount of data involved is too large here. 32 tips for oracle sql query writing and performance tuning view larger image i am working with oracle sql from day when i joined it industry and i have been fascinated by number of things i have learned about sql different databases and its usage over the years.

Select c claimnumber a itemdate c dtn b filepath from items a itempages b keygroupdata c where a itemtype in 112 115 189 241 and a itemnum b itemnum and b itemnum c itemnum order by a datestored desc. 7 4 tracing oracle text includes a tracing facility that enables you to identify bottlenecks in indexing and querying. Sql sql create index ix on t object id. 1 that highlights the real reason bitmap indexes can provide significant performance increases.

How are you fetching the rows. Oracle can do a large number of and or xor stuff to get a targeted set of rowids with only one block visit.