JDBC driver and JDK compatibility issue caused MERGE to fail

Recently, one developer came to me complaining about error ORA-17410. They are using JDBC thin to connect to Oracle databaes. The error was interesting because the application was executing a MERGE statement, which was used to compute quarterly commission fee. Those data would already have been computed on a daily basis and the task would… Continue reading JDBC driver and JDK compatibility issue caused MERGE to fail

Diagnosing DB2 hot page issues

Abstract ________________________________________ Certain types of queries perform worse under increasing user load, due to hash bucket group latch contention caused by hot pages. Symptom ________________________________________ db2pd -latches shows excessive waiters on SQLB_HASH_BUCKET_GROUP_HEADER_groupLatch (“grouplatch”). db2pd -stacks shows excessive EDU waits in latch conflict routines (getConflictComplex) arising from bufferpool routines (sqlbfix, sqlbufix). Cause ________________________________________ There are numerous… Continue reading Diagnosing DB2 hot page issues

Troubleshooting link up/down and autonegotiation

http://etherealmind.com/ethernet-autonegotiation-works-why-how-standard-should-be-set/ http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/17053-46.html Recommended Port Configuration (Autonegotiation or Manual Configuration) There are many opinions on the subject of autonegotiation. Previously, many engineers advised customers not to use autonegotiation with any switch-connected device. However, improvements in the interoperation of autonegotiation and the maturity of the technology has recently changed the view of autonegotiation and its use. In… Continue reading Troubleshooting link up/down and autonegotiation

ORA-01555 encountered when fetch stage is extremely prolonged

We encountered the well-known ORA-1555 error recently : Fri Jun 23 21:07:02 2017 ORA-01555 caused by SQL statement below (SQL ID: a520vskru5tmy, Query Duration=3304 sec, SCN: 0x010a.b517cc1a): SELECT BOND_REPO_DEAL_F.BOND_REPO_DEAL_ID … Query Duration is 3304 seconds, wow! But when I checked the AWR report, it states the Elapsed time for the SQL is only 19.29 seconds.… Continue reading ORA-01555 encountered when fetch stage is extremely prolonged