In the category frequently asked and answered. The question: Can we create indexes on Global Temporary tables (GTT) on the standby Database? The answer is yes, but as always: it depends. I will just answer this with an example. Everything is done on the Read-only Active Data Guard standby database. So, when you create a temporary table SQL> CREATE GLOBAL TEMPORARY TABLE tab2(c1 number, c2 varchar(10)) ON COMMIT PRESERVE ROWS; Table created. SQL> That works as expected, but when you try to add a user index: SQL> create index idx_gtt_tab2 on tab2(c1); create index idx_gtt_tab2 on ..read more

Often asked, well documented but a summary is always good. What are the conditions for the Observer to trigger a fast-start Failover and where do we have to place the observers? As with 19c, you might have noticed that there are less white papers published and however a pdf is easy to read, it is difficult to maintain. The world is evolving rapidly and we want to be able to provide the best and most accurate information regarding best practices possible. That is why we decided to have these good habits in the Oracle Documentation as well! Great isn’t it? The advantage is, that we can update ..read more

The longer Autonomous Data Guard is available, the better it gets and the better it gets, the more questions come up. Some question which hits my mailbox regularly is: This autonomous Data Guard on ADB-S, when you move it to the other side what do we need to change in our connect string. Well, the answer is simple: You do not need to change anything. How does that work? In my earlier post on how to enable Autonomous Data Guard, I have explained on how easy it is to get started with it and we will use this same setup to take it a step further. The first step is to make sure that Autonomous Da ..read more

A common question that often arrives in my mailbox is that redo apply on an Active Data Guard standby database is significantly slower than on the mounted standby. A famous wise man once said: “If the primary can generate it, the standby can apply it”. I totally agree. If the primary can generate it, the standby can apply it. Larry M. Carpenter Let’s start by assuming that the redo apply best practices have been followed and the synchronous best practices or asynchronous best practices, depending on the transport method of choice, have been applied. Following these best practices often solves ..read more

This will be a very short blogpost. It started with an internal question and looking into the documentation, I have noticed that in the VALID_FOR specification for configuration a Log Archive Dest (LAD ), there was some confusion about how you need to specify this. So after a bit of research, Oracle Data Guard accepts these keywords in the VALID_FOR clause: "ONLINE_LOGFILE", "STANDBY_LOGFILE", "ALL_LOGFILES", "PRIMARY_ROLE", "STANDBY_ROLE", "ALL_ROLES", "ONLINE_LOGFILES", "STANDBY_LOGFILES", "ALL_LOGFILES", "PRIMARY_ROLES", "STANDBY_ROLES", "ALL_ROLES" Take into account, that this might chan ..read more

Recently we have announced a new member in the Autonomous family: Autonomous Data Guard. Yes it is really autonomous! All is automatic and it is very easy to use. Here are the first steps on how to use it. The GUI way Create your ADB-S Database. You can do this by clicking the “Create autonomous Database” button. Fill in some basic information Make sure you select a 19c database And of course you will need a good password. For Demo purposes (I will destroy it afterwards anyhow) I took network settings to be available from everywhere, but if you want to deploy it for production use, please ..read more

As pointed out earlier, Oracle Active Data Guard (ADG) is a lot more than just the read-only standby database. One of the technologies no other product beats us on in regards to disaster recovery is the automatic block media recovery, which is part of the Active Data Guard license. This gets automatically enabled when you open the standby database read-only with redo apply enabled. You do not need to do something specific for it, it is just there. In spite of how critical it is to prevent data corruption from the perspective of most DBAs, this is ironically a pretty underestimated feature. It ..read more

Active Data Guard is a lot more than the read-only standby database. Let’s focus on this part a bit. Read-only workloads are select workloads and are just queries. Working on a read-only database where redo apply is running results in a complex mechanism of keeping data up to date and combining it with user queries. From time to time, you can’t help but question the performance of the queries or how the overall standby database is performing. What could possibly be impacting the performance of these queries? We have a very good MOS-note (2409808.1) describing how to gather AWR data in regards ..read more

The OCI tool is easy to use. I had a very interesting conversation with Simon Haslam ( here on Twitter @simon_haslam ) about this. In this blogpost we will highlight the cause (and the solution) of this particular case and in a second part, there is a general workflow which did not let me down for my last deployments. 404 NotAuthorizedOrNotFound Simon and his colleagues are working with ansible and Terraform for automatic provisioning of their full environment which at a certain point in time failed with a 404 error like this ServiceError: { "code": "NotAuthorizedOrNotFound", "message": "Au ..read more

Far Sync is a great technology. When implementing a Disaster Recovery (DR) scenario, the first remark is usually “We want zero Data Loss”. This is exactly what Data Guard is meant for in Synchronous mode. Together with that usually comes “But our second site is really far away”. Those two requirements, don’t mix very well, that is where Far Sync comes into play. Recently I received a question: “but what happens if the network on the Far Sync location is unstable”? Well, we can solve that by adding an alternate Far Sync instance and adding Redo Routes and, as of 12.2, priorities (and eventually ..read more