MTU size
A real life TCP/IP troubleshooting scenario Continue Reading
Author: Nenad Noveljic
Index Organized Table vs. Clustered Index
Comparing efficiency of IOT in Oracle with Clustered Index in SQL Server. Continue Reading
Rescuing Data from Corrupted Tables
This blog post describes how to partially rescue data from corrupted table segments if you find yourself in a miserable position of not having a valid backup at your disposal. Continue Reading
Tables Containing “Current” and “Historical” Rows
If your data model forsees storing “current” and “historical” rows in the same table, there is a chance that there will be queries doing self-joins drived by the “current” rows. This model can give rise to wrong join cardinality estimates applied on skewed data distributions. The more emphasized the skew is, the larger is the error. Table partitioning turns out to be a good solution in such cases. Continue Reading
Density Calculation with Hybrid Histograms
This blog post describes how the calculation of new density has modified with the introduction of hybrid histograms in Oracle 12c. Continue Reading
SPN for SSRS
Troubleshooting Kerberos authentication in SSRS due to SPN Continue Reading
Gathering Statistics with Option ‘gather auto’
In 12c the parameter options was introduced in gather_table_stats. Unfortunately, it doesn’t work as expected. Continue Reading
Disjunctive Subquery Optimization
Disjunctive subqueries are the subqueries which are applied to the or operator. Alternatively, these queries can be rewritten to use the union all operator which may be a more efficient way to retrieve the records from the database. This blog post compares the efficiency of SQL Server and Oracle optimizer when dealing with the transformations of disjunctive subqueries.
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Table Spool Performance Problem
Table Spool can degrade SQL Server performance. Continue Reading
Nested Loop Join Heuristics
Not always the cheapest execution plan gets chosen. This blog post describes such an edge case in SQL Server and Oracle. Continue Reading