What is Oracle Initrans value?
INITRANS specifies the number of DML transaction entries for which space is initially reserved in the data block header. Space is reserved in the headers of all data blocks in the associated segment.
What is PCTFREE?
PCTFREE is a block storage parameter used to specify how much space should be left in a database block for future updates. For example, for PCTFREE=10, Oracle will keep on adding new rows to a block until it is 90% full.
What is a block in Oracle?
Oracle data blocks are the smallest units of storage that Oracle can use or allocate. In contrast, all data at the physical, operating system level is stored in bytes. Each operating system has what is called a block size. Oracle requests data in multiples of Oracle blocks, not operating system blocks.
What is Initrans and Maxtrans?
The INITRANS setting controls Initial Transaction Slots (ITLs). A transaction slot is required for any session that needs to modify a block in an object. For tables INITRANS defaults to 1 for indexes, 2. The MAXTRANS setting controls the maximum number of ITLs that a block can allocate (usually defaults to 255).
What is high water mark in Oracle?
High water mark is the maximum amount of database blocks used so far by a segment. This mark cannot be reset by delete operations.
What is Pctfree in db2?
The PCTFREE clause specifies the percentage of each data page in a table space that is left free when loading or reorganizing the data. For example, the default value for table spaces PCTFREE 5, which means that 5% of each data page is kept free when you load or reorganize the data.
How does Oracle store internal data?
At the finest level of granularity, Oracle Database stores data in data blocks. One logical data block corresponds to a specific number of bytes of physical disk space, for example, 2 KB. Data blocks are the smallest units of storage that Oracle Database can use or allocate.
How big is an Oracle block?
DB_BLOCK_SIZE specifies (in bytes) the size of Oracle database blocks. Typical values are 4096 and 8192 .
What is logging and Nologging in Oracle?
LOGGING/NOLOGGING helps manage enabling direct path writes in order to reduce the generation of REDO and UNDO. It is one of several ways to control the delicate balance between recoverability and performance. Oracle Architecture Background Information. REDO is how Oracle provides durability, the “D” in ACID.
How do I reset my high water mark?
The High Water Mark is the maximum number of blocks which have ever contained data. Deleting records from a table frees up the space but does not move the HWM. In order to reset the High Water Mark we have to drop and recreate the table, or just truncate it.
What is high water mark programming?
The high-water mark is an index into the log file that records the last log entry that is known to have successfully replicated to a Quorum of followers. The leader also passes on the high-water mark to its followers during its replication.
What is Freepage in Db2?
Use the FREEPAGE clause to specify how often Db2 leaves a full page of free space when loading data or when reorganizing data. For example, if you specify FREEPAGE 10, Db2 leaves every tenth page free.