SQL Parser

Question : In my application, I am receiving SQL from other application. I want to validate that SQL text on my client. I don’t want to add the performance overhead to the database , what options are available? Answer: Parsing SQL code is an important part of code development . Parsing is the process of analysing a string of symbols , based on the syntax rules. There a number of options available and will depend on your circumstances. Option 1 – Make a DB2 call and allow the database to validate the SQL code. If you don’t want the overhead... Read more →

SQL1042C An unexpected system error occurred. SQLSTATE=58004

An application owner reported an error on a DB2 database connection attempt. A query on db2diag.log returned this message ADM1710C The database is not accessible because the DB2 database manager cannot write to the log control file "SQLOGCTL.LFH.2" on database partition "0". Possible reasons for this include: the file does not exist; the file is not accessible to the database manager because of network, file system, or OS problems; or incorrect file permissions are preventing the database manager from writing to the file. Ensure that the file is accessible to the database manager and that the file system is functioning... Read more →

Commands to check for read only Linux file system

Checking for read only on the Linux file system is required when investigating certain DB2 problems especially disk errors For example, I saw an error : --from db2diag.log SQL1042C An unexpected system error occurred. SQLSTATE=58004 . --from linux logs Dec 19 08:02:05 server1 kernel: Buffer I/O error on device dm-18, logical block 1562696 Dec 19 08:02:05 server1 kernel: lost page write due to I/O error on dm-18 Dec 19 08:02:05 server1 kernel: SCSI error : <0 0 2 0> return code = 0x20000 Dec 19 08:02:05 server1 kernel: end_request: I/O error, dev sdc, sector 12503752 Some root cause analysis highlighted... Read more →

Deciding to reorg DB2 tables with overflow value

As table data changes , logically sequential data may be on non-sequential physical pages. The database needs to perform added reads . Table Fragmentation leads to a slower response time. DB2 has an option to commit automatic reorganization. They can also be defragmented manually with the REORG command. An example: REORG TABLE user1.”myTable” inplace; The inplace keywords maintains an asynchronous reorganization, allowing write access to the tables during reorgnization. When to commit a REORG? One method is to check the SYSSTAT.TABLES view and watch the overflow value. The overflow value represents row numbers that don’t fit on the original pages... Read more →