Replication is one of the basic and most essential feature available in MySQL. Replication allows you to maintain additional copy of database on another server and keep itself updated with latest changes in master databases. Having another copy of data (other than backup) is always a good option. In case of any issues on master server we can always failover to slave and make it a master. This provides high availability. You can have (more...)
Not a new thing right now since 11.2 is out from some time already.A very common question that I get is that GSD (Group Service Daemon) is offline in 11.2 RAC. That’s not something to be worried about as it’s officially documented in MOS doc# 429966.1. Only if you have 9i database, it would be available but the point is why in 2014, you are still planning to run a 9i (more...)
A recent question on an internal forum asked whether an index on a Foreign Key (FK) constraint designed to avoid locking issues associated with deletes on the parent tables needs to precisely match the columns in the FK. Could the columns in the index potentially be a different order or be appended with additional columns ? The answer is […]
FOR IMMEDIATE RELEASE Cupcake Wars at NoCOUG Spring Conference on May 15 at UCSC Extension Silicon Valley SILICON VALLEY (APRIL 1, 2014) – In a bold experiment aimed at increasing attendance at its awesome educational conferences, the Northern California Oracle Users Group (NoCOUG) is considering changing the format of its spring conference to that of […]
While investigating a question on returing unmatched rows between two tables I set up an example where both tables had indexes which could be used to speed up the query and hopefully return the result set in less time than required for a full table scan. To my surprise when the index was used on the table with the missing record the query returned no rows. Not understanding this behavior (as I KNEW there was (more...)
The Chicago Oracle Users Group (COUG) is finally in its reboot mode. Thanks to Alfredo Abate for taking on the responsibility and bringing the enthusiasm to bring the community back together. Jeremy Schneider has blogged about this here . There is a Linked in Group now open for business and i would recommend every one to contribute and lets make this reboot a success.
I am also going to be presenting at the Ohio (more...)
Funny that oracle can easily cast ‘nan’,'inf’,'infinity’,'-inf’,'-infinity’ to corresponding binary_float_infinity,binary_double_nan, but there is no any format models for to_char(binary_float_infinity,format) or to_binary_***(text_expr,format) that can output the same as to_char(binary_float_infinity)/to_binary_float(‘inf’) without format parameter:
If a BINARY_FLOAT or BINARY_DOUBLE value is converted to CHAR or NCHAR, and the input is either infinity or NaN (not a number), then Oracle always returns the pound signs to replace the value.
SQL> select to_binary_float('inf') from dual;
One of the worst documented areas in OAM; customizing pages with DCC. One revelation: you must use login.pl when you want logout.pl to work, as login.pl seems to build the "Callback URL" list, that logout.pl uses to destroy the session cookies.
As I mentioned in a previous post, Christian Antognini will be the speaker for both the sessions this time. He’ll be covering “12c Adaptive Query Optimization” and “Row Chaining and Row Migration Internals”.
Red Gate Software have kindly offered to sponsor the event again, so registration is free!
I’ve already registered. Please make the effort to come along and support the (more...)
I got email about MapR Sandbox, that is a fully functional Hadoop cluster running on a virtual machine (CentOS 6.5) that provides an intuitive web interface for both developers and administrators to get started with Hadoop. I belief it's a good idea to learn about Hadoop and its ecosystem. Users can download for VMware VM or VirtualBox. I downloaded for VirtualBox and imported it. I changed about network to use "Bridged Adapter". After started... (more...)
Yes that is true, i said it, cellcli can lie to you there are some special cases were the output of cellcli is not the reality and you should double check it’s output with your standard OS tools. So this the output if dcli calling cellcli on an Exadata rack from an client:
In previous posts about caching mechanism of determinstic functions I wrote that cached results are kept only between fetch calls, but there is one exception from this rule: if all function parameters are literals, cached result will not be flushed every fetch call.
Little example with difference:
SQL> create or replace function f_deterministic(p varchar2)
2 return varchar2
7 return p;
SQL> set (more...)
Prior to Oracle 12c truncating tables with dependent children was a pain. We had to disable the constraint before truncating the parent table followed by enabling the constraint. The performance gain achieved using TRUNCATE instead of DELETE almost disappeared if the constraints were enabled with VALIDATE option. If enabling the constraint with NOVALIDATE option was not acceptable, then DELETE seemed to be the only way to go.
Starting with Oracle 12c , Oracle supports truncating (more...)
I discovered a new error today. I was using Data Pump to copy a database from Sun SPARC to X86 and from Oracle 18.104.22.168.0 to 22.214.171.124.0 for testing purposes. I extracted the tablespace creation SQL from the old database like this. (This is only some of it.):
My feelings on this were a bit of a mixed bag. I was not the biggest fan of the original 300 movie at the cinema, but I have subsequently warmed to it. This film adds a bit more story about the lead up to the first film and fills in more details about what happened after, so it is kind-of like a combined prequel-sequel. (more...)
Starting with ASM version 11.2, the ASM spfile can be stored in an ASM disk group. Indeed, during a new ASM installation, the Oracle Universal Installer (OUI) will place the ASM spfile in the disk group that gets created during the installation. This is true for both Oracle Restart (single instance environments) and Cluster installations.
The ASM spfile stored in the disk group, is a registry file, and will always be the ASM metadata (more...)