Technology Questions

Oracle supports 3 transaction isolation levels: 

- Read committed (default)

- Serializable transactions

- Read only

unlink()-deletes the given file from the file system.
unset() -makes a variable undefined.

The classloader is a subsystem of JVM that is used to load classes and interfaces.There are many types of classloaders e.g. Bootstrap classloader, Extension classloader, System classloader, Plugin classloader etc.

- A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index.

- A non clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a non clustered index does not consist of the data pages. Instead, the leaf nodes contain index rows.

Basically there are many standards of Wi-Fi in the industry but some popular of them are 802.11a, 802.11b, 802.11g/n. With the support of these Wi-Fi protocols we can communicate/interact among the devices at the speed of 5Ghz to 2.4Ghz dual band communication.

If we have Wi-Fi nic card so firstly we have to install their drivers and after installation if we have Wi-Fi access point then we can see the signal strength in the right corner below just open that and find the access point to connect, if access point is configured with the security, type the key to connect and enjoy the service.

Wi-Fi is technically referred to as the 802.11 protocol. Over time, Wi-Fi has improved, giving rise to different variations of the protocol.

802.11a – This version operates at 54Mbps. It is considered as the favorite wireless LAN protocol for IP telephony.

- A status occurs when image copy on a table needs to be taken

- The table is available only for queries and can not be updated

- COPY PENDING status can be removed by taking away the image copy or by using REPAIR utility

AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.

The number of distinct values for a column is called index cardinality. DB2's RUNSTATS utility analyzes column value redundancy to determine whether to use a tablespace or index scan to search for data.