Category Archives: Databases

It looks like the Microsoft SQL Database Mirroring a feature I used a lot and for which posted a step by step tutorial that proved to be very popular was deprecated by Microsoft. In a news article on Microsoft site the alternative is presented “Basic Availability Groups (Always On Availability Groups)”. I will summarize in… Read More: #Microsoft SQL Server: Database #Replication (Mirroring) deprecated and replaced by… »

DELETE operations are much faster in case we disable constraints. This is because not all foreign keys affected by the DELETE are indexed. We have to detect all the foreign keys that point to the table from where you delete data. The we can create temporary indices to help speed up the delete. STEP 1.… Read More: Using temporary indices to optimize DELETE operations on big tables… »

Deletes go very slow if the log buffer size is too small and we delete lots of data from big tables. It is very important to have the right settings for log buffer size to avoid having to frequent writes to the disk, writes that cause a high IO traffic that will slow down the… Read More: Optimizing DELETE operations on big tables in #DB2 »

After migrating my full DB2 backup (binaries and data) to a new server I got into several issue. One was already described in the previous post here. ISSUE: Even after fixing that start issue I was still not OK. My WebSphere data source that linked to the DB2 instance was not responding. Trying to ping… Read More: Fix #DB2 SQL1639N ( SQLCODE=-1639, SQLSTATE=08001, SQLERRMC=null) authentication issue »

I moved my DB2 installation to a new server from a full back-up. After performing all the necessary steps: 1. Recreate the necessary users: db2inst1, db2fenc1, db2das1 2. Give ownership to their home directories ISSUE: I tried to start the instance. I logged in to the db2inst1 user and started the database. This was the… Read More: Fix #DB2 Communication protocol failed to start issue: SQL5043N »

“Invisible columns”: This is a new feature introduced in Oracle 12c that got me all excited.In short you can now have hidden columns in a table that are not visible to the standard SELECT, INSERT clauses if you do not want to. Some usage for this: Legacy application queries I hate how you have to… Read More: #Oracle 12c invisible columns »