What is All_rows hint in Oracle?
The ALL_ROWS hint explicitly chooses the cost-based approach to optimize a statement block with a goal of best throughput (that is, minimum total resource consumption).
Can we avoid index by using hint in Oracle?
Table Hints. Suppose you want to use a specific index for your query to avoid a table scan, we can use table hints. One of the popular table hints is WITH(NOLOCK) to avoid default transaction isolation level and avoid locking issues in Select statements.
How many types of hints are there in Oracle?
1 Types of Hints. Single-table hints are specified on one table or view. INDEX and USE_NL are examples of single-table hints. Multi-table hints are like single-table hints, except that the hint can specify one or more tables or views.
How do you use parallel hint in select statement?
Example# Statement-level parallel hints are the easiest: SELECT /*+ PARALLEL(8) */ first_name, last_name FROM employee emp; Object-level parallel hints give more control but are more prone to errors; developers often forget to use the alias instead of the object name, or they forget to include some objects.
How do I use index hint?
Use the INDEX hint for function-based, domain, B-tree, bitmap, and bitmap join indexes. When working with tables containing ST_Geometry attributes and a st_spatial_index, specify the Oracle INDEX hint and the name of the st_spatial_index to instruct the optimizer to access the data by way of the index.
What is an index hint?
Index hints are used to force a query to use a specific index, instead of allowing SQL Server’s Query Optimizer to choose what it deems the best index. In some cases you may gain benefits by specifying the index a query must use.
How can I get distinct values for a particular column in SQL?
To get unique or distinct values of a column in MySQL Table, use the following SQL Query. SELECT DISTINCT(column_name) FROM your_table_name; You can select distinct values for one or more columns. The column names has to be separated with comma.
Can you SELECT multiple distinct columns in SQL?
Answer. Yes, the DISTINCT clause can be applied to any valid SELECT query. It is important to note that DISTINCT will filter out all rows that are not unique in terms of all selected columns. Feel free to test this out in the editor to see what happens!