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dbs/db4/parallel_alter_tables - Allow ALTER TABLE while INSERTS occur in parallel
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| Parameter: dbs/db4/parallel_alter_tables |
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| Short description: Allow ALTER TABLE while INSERTS occur in parallel |
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| Parameter description: |
| ---------------------- |
| |
| See SAP Note 960392 for full details. The following is an excerpt |
| from the SAP note. |
| |
| ALTER TABLE may require exclusive locks on a TABLE. Continual |
| activity on the TABLE may starve the ALTER TABLE request. For |
| example, ALTER activity may be frequent on Partitioned Tables in |
| which partitions are added and dropped. |
| |
| The Parallel Alter feature actively monitors a definable set of |
| tables that need coordination; then intelligently schedules read, |
| write and alter operations to prevent alter starvation. |
| |
| ----- |
| Setup |
| ----- |
| |
| o Specify the profile parameter in the DEFAULT.PFL (see below) |
| |
| o End ALL Application Server Instances of the SAP System |
| |
| o Delete SQL Packages |
| |
| ------------------------------ |
| Building the Profile Parameter |
| ------------------------------ |
| |
| +------------------------------------------------------------+ |
| |Note: Allow us to help you! | |
| |--------------------------- | |
| | | |
| | If you are considering using this feature, feel free to | |
| | open a OSS message to the BC-DB-DB4 queue and we'll work | |
| | with you to build an appropriate monitoring string. | |
| +------------------------------------------------------------+ |
| |
| The table(s) that need to be coordinated by must be specified via |
| profile parameter in: |
| |
| o /usr/sap/<SID>/sys/profile/DEFAULT.PFL |
| |
| The profile parameter has the following format: |
| |
| o dbs/db4/parallel_alter_tables = <LockGroup> = <TableName>, et
| |
| Where: <TableName> is the name of the table or view to be monitored |
| for coordination. <TableName> can contain wildcards ? and *. Where ?|
| matches any ONE single character, and * matches many. LeTeR cAsE iS |
| iGnOrEd. |
| |
| Where: <LockGroup> is an arbitrary name that specifies the name of |
| the lock. Multiple tables or views that resolve to the same |
| <LockGroup> are coordinated together. <LockGroup> can contain
| variables %n that correspond to the respective wildcard in |
| <TableName>. |
| |
| Example: |
| |
| - dbs/db4/parallel_alter_tables = MYLOCK=MY*, YOURLOCK=YOUR* |
| |
| Would coordinate all of "MY" tables as one group, and all of |
| "YOUR" tables as another. |
| |
| Example: |
| |
| - dbs/db4/parallel_alter_tables = Lock_%0 = ?* |
| |
| Would coordinate all tables on the system, using a <LockGroup> |
| equal to the first character of every table. So tables SFLIGHT |
| and SVERS would both resolve to Lock_S. |
| |
| Table Views complicate the specification. Because the LIB_DBSL only |
| "sees" SQL Text, views that reference "coordinated tables" must also |
| be listed in the profile parameter. |
| |
| - dbs/db4/parallel_alter_tables = LOCK_%0=*TABLE, LOCK_%0=*VIEW |
| |
| Would put all tables and views that start with the same prefix |
| and that end either on TABLE or on VIEW into the same lock |
| group. So MYAPPTABLE and MYAPPVIEW are coordinated together |
| because they have a lock name of LOCK_MYAPP. |
| |
| When active, the developer trace shows (for example): |
| |
| C parallel_alter_tables = LOCK_%0=*TABLE |
| C = LOCK_%0=*VIEW |
| |
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| Application area: Database |
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| Unit: |
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| Default value: '' |
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| Person(s) allowed to make changes: |
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| Limitations for the operating systems: |
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| Limitations for database systems: DB2/400 |
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| Are other parameters affected or dependent: |
| |
| dbs/db4/parallel_alter_instance |
| |
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| Valid entries, formats, areas: |
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| Short Description : Allow ALTER TABLE while INSERTS occur in parallel
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| Applications Area : Database
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| Parameter Type : S
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| Changes allowed : X
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| Valid for Operating System : *
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| Dynamic switchable :
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| Same on all Servers : X
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This documentation is copyright by SAP AG.
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