Create tablespace command in oracle 12c,pvc pipe stand for laptop,woodworking plans for a corner shelf,build shelf supports 5mm - Test Out

28.07.2013
The Oracle create tablespace statement can be quite complex if you look at it in the Oracle documentation. We will be looking at all three types of Oracle tablespace later on in this article, but first let’s cover some basics.
Top Tip: If you are going to have a large tablespace in your database try to have fewer physical datafiles which make the tablespace because when Oracle does a checkpoint, among other operations, it has to update each datafile header. DATAFILE – This next section lists out all of the physical datafiles you will be creating.
Note: Autoextend can actually cause tablespace to grow by up to 10% of the total size of the tablespace! I would like to go into a little more detail for the extent management, uniform size and segment space management clauses which I will do in the next sections. Extents are created as the segment grows and can span multiple datafiles but all extents for the same segment must be in the same tablespace. In a locally managed tablespace, free and used blocks are managed by something called a bitmap in the datafile header. Note: In general, the only time that a used extent will be given back to the tablespace for use by another segment will be if the original segment is dropped.
Uniform size means that each extent will be the same size, like when building a house each brick will be the same size so will fit together nicely with no wasted space. Auto allocated extents, on the other hand, will usually start small and an internal algorithm will determine how large to make the next extent, and the one after that, etc. This type of extent is like a house made of odd shaped bricks – there will be gaps and finding a space to fit an odd shaped brick will be difficult!
With automatic segment space management (the default for locally managed tablespace) free space in each segment is managed very much in the same way that the extent management is; using bitmaps, but for the segment this information is kept in the first block allocated to the segment at creation time. When using manual segment space management the free and used blocks are managed using free lists, which require more management when inserts, updates and deletes are run against the segment.
Note: When using automatic segment space management, only the PCTFREE storage parameter is valid when creating a segment.
Traditionally, Oracle only had one type of tablespace, which is now what is called a smallfile tablespace. Note: Unless you have changed the database default all of your tablespaces will be created as smallfile ones, but you can explicitly create bigfile tablespaces. Temporary tablespaces are very important for ensuring that sorts, like index creations and SQL queries, can complete if they run out of PGA to sort the results in. I have written another article about UNDO, what it is, how to monitor it, etc so have a read of that first if you are not familiar with the basic concepts. If you used the DBCA to create your database it should have automatically created an UNDO tablespace for you, if you created an 11g database. If you didn’t use the DBCA and ran the CREATE DATABASE statement manually, the UNDO tablespace would have been created automatically if the UNDO_MANAGEMENT = AUTO parameter was configured.
I hope that the information I have provided in the article has been of use to you, and as always please leave a comment if you have anything to say.
Use the CREATE TABLESPACE statement to create a tablespace, which is an allocation of space in the database that can contain schema objects.
An undo tablespace is a type of permanent tablespace used by Oracle Database to manage undo data if you are running your database in automatic undo management mode. Before you can create a tablespace, you must create a database to contain it, and the database must be open.
If you are running the database in automatic undo management mode, then at least one UNDO tablespace must be online. If you are running the database in manual undo management mode, then at least one rollback segment other than the SYSTEM rollback segment must be online. A bigfile tablespace contains only one datafile or tempfile, which can contain up to approximately 4 billion (232) blocks. A smallfile tablespace is a traditional Oracle tablespace, which can contain 1022 datafiles or tempfiles, each of which can contain up to approximately 4 million (222) blocks. If you omit this clause, then Oracle Database uses the current default tablespace type of permanent or temporary tablespace set for the database. You can specify only one datafile in the DATAFILE clause or one tempfile in the TEMPFILE clause. You must specify EXTENT MANAGEMENT LOCAL and SEGMENT SPACE MANAGEMENT AUTO for the SYSAUX tablespace. Restrictions on the SYSAUX Tablespace You cannot specify OFFLINE or TEMPORARY for the SYSAUX tablespace.
Specify the datafiles to make up the permanent tablespace or the tempfiles to make up the temporary tablespace. For operating systems that support raw devices, the REUSE keyword of datafile_tempfile_spec has no meaning when specifying a raw device as a datafile.
You can create a tablespace within an Automatic Storage Management disk group by providing only the disk group name in the datafile_tempfile_spec. If you use one of the reference forms of the ASM_filename, which refers to an existing file, then you must also specify REUSE.
On some operating systems, Oracle does not allocate space for a tempfile until the tempfile blocks are actually accessed.
Restriction on BLOCKSIZE You cannot specify nonstandard block sizes for a temporary tablespace or if you intend to assign this tablespace as the temporary tablespace for any users. Specify the default logging attributes of all tables, indexes, materialized views, materialized view logs, and partitions within the tablespace. The tablespace-level logging attribute can be overridden by logging specifications at the table, index, materialized view, materialized view log, and partition levels.
Restriction on Forced Logging You cannot specify FORCE LOGGING for an undo or temporary tablespace. This clause lets you specify default storage parameters for all objects created in the tablespace and default compression of data for all tables created in the tablespace.
ONLINE  Specify ONLINE to make the tablespace available immediately after creation to users who have been granted access to the tablespace. OFFLINE  Specify OFFLINE to make the tablespace unavailable immediately after creation. The data dictionary view DBA_TABLESPACES indicates whether each tablespace is online or offline. In earlier releases, you could specify the TEMPORARY keyword after specifying the tablespace name to create a temporary tablespace.
Oracle strongly recommends that you create locally managed temporary tablespaces containing tempfiles by using the temporary_tablespace_clause. The extent_management_clause lets you specify how the extents of the tablespace will be managed.
After you have specified extent management with this clause, you can change extent management only by migrating the tablespace. UNIFORM specifies that the tablespace is managed with uniform extents of SIZE bytes.The default SIZE is 1 megabyte.
Restriction on Dictionary-managed Tablespaces You cannot specify DICTIONARY if the SYSTEM tablespace of the database is locally managed or if you have specified the temporary_tablespace_clause. If you do not specify the extent_management_clause, then Oracle Database interprets the MINIMUM EXTENT clause and the DEFAULT storage_clause to determine extent management.
If you do not specify the DEFAULT storage_clause, then the database creates a locally managed autoallocated tablespace.
If you specified the MINIMUM EXTENT clause, then the database evaluates whether the values of MINIMUM EXTENT, INITIAL, and NEXT are equal and the value of PCTINCREASE is 0.


If you did not specify MINIMUM EXTENT clause, then the database evaluates only whether the storage values of INITIAL and NEXT are equal and PCTINCREASE is 0. If you specify LOCAL, then you cannot specify DEFAULT storage_clause, MINIMUM EXTENT, or the temporary_tablespace_clause. AUTO  Specify AUTO if you want the database to manage the free space of segments in the tablespace using a bitmap.
MANUAL Specify MANUAL if you want the database to manage the free space of segments in the tablespace using free lists. If you set extent management to LOCAL UNIFORM, then you must ensure that each extent contains at least 5 database blocks. If you set extent management to LOCAL AUTOALLOCATE, and if the database block size is 16K or greater, then Oracle manages segment space by creating extents with a minimum size of 5 blocks rounded up to 64K.
Use this clause in conjunction with the ALTER DATABASE FLASHBACK clause to specify whether the tablespace can participate in FLASHBACK DATABASE operations.
The FLASHBACK mode of a tablespace is independent of the FLASHBACK mode of an individual table.
Use this clause to create a locally managed temporary tablespace, which is an allocation of space in the database that can contain transient data that persists only for the duration of a session.
The transient data can be user-generated schema objects such as temporary tables or system-generated data such as temp space used by hash joins and sort operations. Specify an empty string (' ') to indicate that tablespace is not a member of any tablespace group. Restrictions on Temporary Tablespaces The data stored in temporary tablespaces persists only for the duration of a session. Oracle Database always assigns an undo tablespace when you start up the database in automatic undo management mode. RETENTION GUARANTEE specifies that Oracle Database should preserve unexpired undo data in all undo segments of tablespace even if doing so forces the failure of ongoing operations that need undo space in those segments. The only clauses you can specify for an undo tablespace are the DATAFILE clause and the extent_management_clause to specify local extent management. If we assume that the default database block size is 2K, and that each bit in the map represents one extent, then each bit maps 2,500 blocks. The following example sets the default location for datafile creation and then creates a tablespace with an Oracle-managed tempfile in the default location.
This statement creates a locally managed tablespace in which every extent is 128K and each bit in the bit map describes 64 blocks. Scripting on this page enhances content navigation, but does not change the content in any way.
MINEXTENTS - controls free space fragmentation ensuring that every used and free extent size is at least as large as and is a multiple of MINEXTENTS.
NEXT - disk space to be allocated to the datafile in the current tablespace when more space is required. MAXSIZE - maximum disk space allowed for automatic extension allocation to the datafile within the tablespace. NOLOGGING - no undo and redo logs are generated for operations that support the NOLOGGING option on tables, indexes and partitions in the tablespace.
LOCAL - a locally managed tablespace manages its own extents and particularly the addition of new extents when the tablespace size is increased.
Tablespaces can be altered to add datafiles, change online status, recoverability, backup status and tablespace default storage characteristics. ONLINE - attempting to put a tablespace ONLINE when previously not taken OFFLINE cleanly requires media recovery on the tablespace. For a dictionary-managed tablespace, the only storage parameter you can specify with this clause is COMPRESS. Assuming that the default database block size is 2K, and that each bit in the map represents one extent, then each bit maps 2,500 blocks. In this article I would like to try and break down the create tablespace command in to simpler terminology. There are a lot of options you have to consider when creating an Oracle tablespace, but let’s just use an example of how I would normally create one and then look at the statements in a little more detail.
This is like a map of all blocks in the datafile, conceptually, it has a value of 1 if the block is used and a 0 if it is empty. The datafile bitmap will be scanned to see if there is a large enough chunk of disk space to create the new extent. Just deleting all rows in a segment will not release the extent back for use by another segment. They will most likely be larger each time if the segment is growing rapidly and smaller if it is not. It is also a single point of contention, so automatic management is generally accepted as the more efficient method to use. This is what percentage of free space should be left in each block for subsequent updates to existing rows.
In an ideal world all the sorting would be done in memory because it’s much more efficient but the TEMP tablespace acts as an overspill area.
The UNDO tablespace is so fundamental to the smooth operation of the database that it should definitely not be overlooked. Oracle strongly recommends that you use automatic undo management mode rather than using rollback segments for undo. You can subsequently use the ALTER TABLESPACE statement to take the tablespace offline or online, add datafiles or tempfiles to it, or make it a read-only tablespace. If you specify BIGFILE for a permanent tablespace, then the database by default creates a locally managed tablespace with automatic segment-space management. You must use the CREATE TABLESPACE statement to create the SYSAUX tablespace if you are upgrading from a release prior to Oracle Database 10g. Use the datafile_tempfile_spec form of file_specification to create regular datafiles and tempfiles in an operating system file system or to create Automatic Storage Management disk group files. For Automatic Storage Management diskgroup files, the parameter must be set to a multiple file creation form of Automatic Storage Management filenames. In this case, Automatic Storage Management creates a datafile in the specified disk group with a system-generated filename. This delay in space allocation results in faster creation and resizing of tempfiles, but it requires that sufficient disk space is available when the tempfiles are later used. Oracle Database will log all changes to all objects in the tablespace except changes to temporary segments, overriding any NOLOGGING setting for individual objects. Please refer to Oracle Database Administrator's Guide for information on when to use this setting. Oracle strongly recommends that you create tablespaces that are locally managed rather than dictionary managed.
All extents of temporary tablespaces are of uniform size, so this keyword is optional for a temporary tablespace. Locally managed tablespaces are much more efficiently managed than dictionary-managed tablespaces.
If they are equal, then the database creates a locally managed uniform tablespace with extent size = INITIAL. If you need a locally managed tablespace to store temporary objects, for example, if you will assign it as a user's temporary tablespace, then use the temporary_tablespace_clause. It lets you specify whether Oracle Database should track the used and free space in the segments in the tablespace using free lists or bitmaps.
If you specify AUTO, then the database ignores any specification for PCTUSED, FREELIST, and FREELIST GROUPS in subsequent storage specifications for objects in this tablespace.


Oracle strongly recommends that you do not use this setting and that you create tablespaces with automatic segment-space management. This clause is useful if you have the database in FLASHBACK mode but you do not want Oracle Database to maintain Flashback log data for this tablespace. Oracle Database will save Flashback log data for this tablespace and the tablespace can participate in a FLASHBACK DATABASE operation.
When a temporary tablespace, or a tablespace group of which this tablespace is a member, is assigned to a particular user, then Oracle Database uses the tablespace for sorting operations in transactions initiated by that user. Therefore, only a subset of the CREATE TABLESPACE clauses are relevant for temporary tablespaces. When you run the database in automatic undo management mode, Oracle Database manages undo space using the undo tablespace instead of rollback segments. If no undo tablespace has been assigned to this instance, then the database uses the SYSTEM rollback segment. This setting is useful if you need to issue an Oracle Flashback Query or an Oracle Flashback Transaction Query to diagnose and correct a problem with the data.
Space occupied by unexpired undo data in undo segments can be consumed if necessary by ongoing transactions.
This can use up large amounts of disk space since when records are deleted from datafiles already allocated extended space that is not reclaimed by the operating system or released by Oracle.
The tablespace-level logging attribute can be over-ridden by logging specifications at the table, index and partition levels.
The uniform size parameter should be set to an exact multiple of the SORT_AREA_SIZE parameter size for in-memory sorting in the SGA.
Can be done with tablespace online or offline as long as datafile not in use by another database. You must use the CREATE TABLESPACE statement to create the SYSAUX tablespace if you are upgrading from a release prior to Oracle Database 11g. For Automatic Storage Management disk group files, the parameter must be set to a multiple file creation form of Automatic Storage Management filenames.
You must create an unencrypted tablespace and re-create the database objects in the unencrypted tablespace.
The only clause of encryption_spec that is relevant for tablespace encryption is the USING clause. Oracle Database determines the size of each extent and the total number of extents allocated to satisfy the initial segment size. I’d recommend something like using the database name, the user who will have objects in it and the extent size. This is one of the advantages of using locally managed tablespaces; the block management is done efficiently, and all blocks which are next to one another and free can be used. When it finds which blocks to use for the new extent, the bitmap is updated to indicate that the blocks are now used and the segment will have some free space to use.
With the increasing size of modern day databases, Oracle decided to add a bigfile tablespace to the mix.
Have a read about it in my article on monitoring TEMP space as it will give you some useful queries and tips.
You must have the SYSDBA system privilege to specify this clause, and you must have opened the database in MIGRATE mode. If this parameter is set, then the database creates a system-named 100 MB file in the default file destination specified in the parameter.
The datafile is auto-extensible with an unlimited maximum size and a default size of 100 MB. To avoid potential problems, before you create or resize a tempfile, ensure that the available disk space exceeds the size of the new tempfile or the increased size of a resized tempfile.
This clause lets you control free space fragmentation in the tablespace by ensuring that the size of every used or free extent in a tablespace is at least as large as, and is a multiple of, the value specified in the size_clause.
In this case, NOLOGGING is the default logging mode for objects subsequently created in the tablespace, but the database ignores this default as long as the tablespace or the database is in FORCE LOGGING mode. It is still supported in case you are using dictionary-managed tablespaces, which are not supported by the CREATE TEMPORARY TABLESPACE syntax. If the MINIMUM EXTENT, INITIAL, and NEXT parameters are not equal, or if PCTINCREASE is not 0, then the database ignores any extent storage parameters you may specify and creates a locally managed, autoallocated tablespace. You must take the datafiles in this tablespace offline or drop them prior to any subsequent FLASHBACK DATABASE operation. A tablespace group lets you assign multiple temporary tablespaces to a single user and increases the addressability of temporary tablespaces. If the tablespace group already exists, then Oracle Database adds the new tablespace to that group. The only clauses you can specify for a temporary tablespace are the TEMPFILE clause, the tablespace_group_clause, and the extent_management_clause. This clause is useful if you are now running in automatic undo management mode but your database was not created in automatic undo management mode. You can avoid this by creating an undo tablespace, which the database will implicitly assign to the instance if no other undo tablespace is currently assigned.
BEGIN BACKUP can not be used on a read-only tablespace and can only be used in ARCHIVELOG mode. A tablespace left in BACKUP mode will make the database think it requires recovery on shut down and may become unrecoverable on restart.
You must also specify the ENCRYPT keyword as part of the DEFAULT storage_clause in this statement in order for the tablespace to be encrypted. This is ideal for allowing the database objects to grow without having to always manually add space. Each extent can vary in size or can be of uniform size, depending on how you have created the tablespace. The excess space should allow for anticipated increases in disk space use by unrelated operations as well.
If you subsequently take the tablespace out of FORCE LOGGING mode, then the NOLOGGING default is once again enforced. If you do use this syntax, you cannot specify the EXTENT MANAGEMENT LOCAL clause or the BLOCKSIZE clause. If the tablespace group does not exist, then the database creates the group and adds the new tablespace to that group. The BEGIN BACKUP command suspends updates to the header block of the datafiles for the referenced tablespace and places the redo logs into block mode where entire changed blocks instead of just the transactions are recorded.
END BACKUP can not be used on a read-only tablespace and can only be used in ARCHIVELOG mode. This will mean that each datafile will be listed on disk in order for any datafile from 001 to 999.
The statement also allows assign the ownership of tablespace to another user specified in the ONWER clause.The directory_path is the absolute path to an empty directory used for the tablespace. Move the datafiles in the operating and then use the ALTER TABLESPACE RENAME command to alter the pointers to those files in the database. If the tablespace will be offline for an extended period users can be reassigned to other tablespaces using the ALTER USER command. SET ENCRYPTION WALLET clause to load information from the server wallet into memory for database access.



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