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).
How many types of segments are there in Oracle?
There are four types of segments used in Oracle databases: data segments.
What is pct in database?
What is PCT increase parameter in segment? PCTFREE is a parameter used to find how much space should be left in a database block for future updates. This means that if the PCTFREE = 20, new rows will be added in the block until it is 80% full.
What is ITL wait events in Oracle?
What is an ITL Wait. If a block is so packed that the the ITL cannot grow to create a free slot, then the transaction that needs to lock a row waits, till a slot becomes available. This wait is termed as ITL waits and can be seen when from v$session_wait is the session is waiting.
What is ENQ allocate ITL entry?
Answer: The event “enq: TX – allocate ITL entry” indicates “enqueues” (locks) that are waiting for serial access to Oracle resources, in this case the transaction is waiting for a lock that is held by a competing session.
What is high level watermark?
A high-water mark is the highest level in value an investment account or fund has reached. A high-water mark is often used as a demarcation point in determining performance fees that an investor must pay.
What is row chaining in Oracle?
Row chaining occurs when a row can’t physically fit into an Oracle block. Another block is required to store the remainder of the row. Chaining can cause serious performance problems and is especially prevalent with those storing multimedia data or large binary objects (blobs).
What is SGA and PGA memory?
Basic Memory Structures All server and background processes share the SGA. Examples of data stored in the SGA include cached data blocks and shared SQL areas. Program global area (PGA) A PGA is a nonshared memory region that contains data and control information exclusively for use by an Oracle process.
Which three are types of segments in an Oracle database?
Explain different types of segment.
- Data Segments : There is a single data segment to hold all the data of every non clustered table in an oracle database.
- Index Segments : Every index in an Oracle database has a single index segment to hold all of its data.
- Rollback Segments :
- Types of rollbacks :
- Temporary Segments :
What is Oracle PCT?
From Oracle FAQ. 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. This leaves 10% for future updates (row expansion).
What is block ID in Oracle?
BLOCK_ID NUMBER Starting block number of the extent — example 1001. BYTES NUMBER Size of the extent in bytes. BLOCKS NUMBER Size of the extent in Oracle blocks —size in terms of blocks – that is extent size – add all to the inital extent and – 1 => you will last block id. 1001 + 100 = 1101 – 1= 1100 = last block.