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Articles on Trending Technologies
Technical articles with clear explanations and examples
Semaphore in Java
A semaphore is used to control access to a shared resource when a process is being executed. This is done with the help of a counter. When this counter value is greater than 0, access to share resource is provided. On the other hand, if the value of counter is zero, then access to shared resources is denied. The counter basically keeps a count of the number of permissions it has given to the shared resource. This means, a semaphore provides access to a shared resource for a thread.Semaphores are present in the java.util.concurrent package. The concept of semaphore is ...
Read MoreMultiMap in Java
Multimap is a general method to bind the keys with random multiple values. The Multimap framework in Guava has methods that help in dealing with mapping keys to multiple values. Multimap can be visualized as a framework that −Is a collection of mapping from one key to one specific valueIs a collection of mapping from unique key to multiple values, i.e. collection of values.It can be implemented in places that use Map.Advantages of MultimapAn empty collection need not be populated before added a key value pair with the help of the function ‘put’.The ‘get’ method doesn’t return a null, except ...
Read MoreGive the panel command to start a specific tablespace within a DB2 database.
To start a specific tablespace within a DB2 database we can use below panel command.START DATABASE (DSNDB01) SPACENAM(TABSPAC1)Using the START DATABASE command, we can also start database and indexspace.
Read MoreGive and explain the panel command to display all the components of DB2 database DSNDB01 along with their status?
A database contains multiple components like tablespace, indexspace, index, tables, etc. We can find out all the components within the database using the below panel command.DIS DB(DSNDB01)
Read MoreWhat are the ways to calculate DB2 database size using DB2 utility and other methods?
There are multiple ways in which we can estimate the size of the DB2 database. Few of them are listed below−By using inbuilt get_dbsize_info function.By using DB2 active transaction logs.The size of the dataset which was used with UNLOAD utility can be checked.Table/Index dataUsing STOSPACE utility in JCL as below//STEP1 EXEC DSNUPROC //SYSIN DD * STOSPACE DATABASE DSNDB01 //*
Read MoreHow to repair a pending state of an index IDX1?
The pending state is set when the image copy is required for the table space or when the INDEX is in rebuild status. In this case a COPY PENDING/ REBUILD PENDING flag is set. We can repair this state by using the below JCL step.//STEP010 EXEC DSNUPROC REPAIR SET INDEX IDX1 NORBDPENDThis utility can also be used to repair the tablespace. For this we can use the REPAIR SET TABLESPACE statement. This is followed by the name of index or tablespace.
Read MoreHow to reorganize the DB2 tablespace TABSPAC1 to reclaim fragmented space?
The tablespace reorganization is used to reorganize the data present in the system in order to reclaim the free space. This free space can be utilized to store the new data and therefore reorganization is very useful from a memory utilization point of view. We can reorganize any tablespace using DB2 REORG utility in JCL step as below.//STEP1 EXEC DSNUPROC,UID='IUJLU101.REORG', //UTPRINT DD SYSOUT=* //SYSIN DD * REORG TABLESPACE (DBSET1.TABSPAC1) //*The REORG TABLESPACE statement is followed by the name of the tablespace which needs to be reorganized qualified by dabasebase.
Read MoreUpdating and sampling of catalog statistics for DB2 tablespace
The DB2 RUNSTAT utility records the details of tablespace, table, index, etc in the system catalog. The RUNSTAT generates the data like space available in table space, indexes, access paths, etc. We can use the below JCL step to update the catalog statistics of DB2 tablespace TABSPAC2 and to sample 25% of the rows.//STEP1 EXEC DSNUPROC //UTPRINT DD SYSOUT=* //SYSIN DD * RUNSTATS TABLESPACE DBSET1.TABSPAC1 TABLE(ALL) SAMPLE 25 INDEX(ALL)The SYSIN parameter can be used with RUNSTATS TABLESPACE statement followed by tablespace name qualified by database name.
Read MoreHow to start a DB2 database DSNDB001 using the command panel?
We can start the DB2 database by giving below command in panelDB2 ACTIVATE DSNDB001The DB2 ACTIVATE is followed by the name of the database which needs to be started.
Read MoreHow to recover a DB2 table space TABSPC1 using the image copy TOLASTCOPY?
The DB2 provides an utility RECOVER which is used to restore the tablespace. This utility uses image copy and DB2 logs to restore the changes. The following command can be used to recover the tablespace to the last image copy that was taken.RECOVER TABLESPACE DBSET1.TABSPAC1 TOLASTCOPYThe RECOVER TABLESPACE is followed by the name of tablespace qualified by the database in which it resides. The TOLASTCOPY parameter will restore the image copy in the following way. If the most recent image copy is full image copy, then the full image copy is restored in the tablespace. If the most recent image ...
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