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Dropping an Informix database in use2021-12-21T12:22:25+00:00

Abstract

Scripts are often created to refresh test databases – either scheduled overnight or on demand – so that QA or development teams can validate or debug schema and application changes against the latest realistic data. An easy solution is to run a full instance restore using ontape or onbar from the last production archive, but sometimes many copies of the database are required for different projects or testing stages running in parallel, and avoiding the overhead of a separate instance each can be desirable. This means that, before any database can be restored using dbimport or similar, it first needs to be dropped, which is impossible when in use, as an exclusive database lock must be applied. This article provides a script to achieve that, even if there are continual concurrent connection attempts by applications.

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How to list temp dbspace contents2021-11-26T14:22:48+00:00

Updated November 2021

Abstract

If an Informix instance warns that one of your temp dbspaces is full, it is useful to have SQL quickly to list what it contains, or to be run automatically if dbspace usage goes over a maximum acceptable percentage. Such a “sysmaster” query is provided in this article.

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Informix Table Restore2021-11-19T15:09:26+00:00

Abstract

However you back up your Informix Dynamic Server (IDS) instance, a long-standing method exists to restore a single table as at a given point in time. This is described elsewhere, but some awkward coding is required. If someone has accidentally emptied a production table, you would want a very fast way to reinstate it with minimal manual steps. This article provides a script to help achieve that, together with setup and example usage.

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Informix assert file lock analysis2021-11-23T14:02:16+00:00

Abstract

This article provides a script to analyse what database objects were locked when IBM Informix Dynamic Server (IDS) “asserts” (saves an evidence file) including what sessions were waiting on another, which is particularly useful to diagnose deadlocks.

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InformixHQ Startup Sensor2021-11-23T14:01:42+00:00

Abstract

This article provides a stored procedure to run InformixHQ (HQ) Java processes automatically whenever IBM Informix Dynamic Server (IDS) has been restarted, as originally posted on the community forum here. It follows on from the previous article InformixHQ Setup and uses the shell script “informix-control.sh” it contains which starts or stops HQ.

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Revalidating Informix foreign key data2021-11-23T14:01:23+00:00

Abstract

When testing a database migration to a new platform that is not compatible, for example with a different OS or locale, you cannot restore from a level 0 archive on the new server. Data must be copied either via flat files or directly using SQL tools. If this is from a live database that is being updated and cannot be exclusively locked (which rules out dbexport), you cannot guarantee consistency of the data being reloaded, so NOVALIDATE must be set to ensure foreign keys can be reapplied. This article provides stored procedure language (SPL) code to identify and delete any resulting invalid data.

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Informix replication to SPL routine2021-12-16T13:14:33+00:00

Updated December 2021

Abstract

This new feature, documented here, was introduced with IBM Informix Dynamic Server (IDS) version 14.10. It is an enhancement to Enterprise Replication (ER) allowing for data changes to be handled by a stored procedure rather than being applied directly to a replica table. It is very likely to be used in a Loopback Replication arrangement, so that the stored procedure fired is contained in the same database as the source table. Such a replicate is also known as an “asynchronous post-commit trigger”. This is because, unlike a conventional trigger, it runs in background with respect to the calling application and occurs after the transaction has been committed. ER infrastructure should ensure reliable buffering and delivery should a backlog build up or if the server is restarted. This article gives an example of how this might be useful to perform whatever type of action you wish when data changes have been committed.

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Informix loopback replication2021-06-18T15:50:44+01:00

Abstract

This relatively new feature, documented here, was introduced with IBM Informix Dynamic Server (IDS) version 12.10.xC11 in March 2018, enabling replication of tables within the same database or instance. It is an enhancement to Enterprise Replication (ER) which was previously only supported between different instances. This article gives an example of how it can reduce downtime when slow schema changes are required on large tables in continuous use.

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Informix “cdr migrate server”2021-06-08T09:37:18+01:00

Abstract

This new command, documented here, was introduced with IBM Informix Dynamic Server (IDS) version 14.10.xC2 in September 2019. In theory, it reduces the effort involved in creating a new active-active replica instance to a single command. It uses Enterprise Replication (ER) which supports participating servers being on different Informix versions or operating systems, providing a unique route for platform migration with almost zero downtime. The complex work to achieve this with ER was previously a major disincentive. This article looks at the current reality of “cdr migrate server” (CMS), showing that it can achieve its goal if some pitfalls are avoided. CMS should not be confused with the earlier ifxclone command to automate the creation of another node in a high-availability cluster, which must be on the same platform and version as the source server.

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Genero 3.20 Remote Development2021-06-07T17:07:49+01:00

Abstract

With the popularity of home and coworking space working arrangements, along with company BYOD policies, being able to develop Genero applications from any location, and on different devices is becoming a must. Genero Studio has had a client/server development model for a while; however, up until now, this has worked best in a LAN environment.  Previously this relied on the client sharing a filesystem on the server, which required a fast and solid network connection between the two to be practical.  Technologies such as SMB were not designed to run over the Internet, and doing so can be cumbersome and insecure. Previously, the only work-around for this was to use a remote desktop solution, which could still be slow and impractical, especially when designing forms and reports.  This also negates many of the benefits of having a modern workstation with fast processor and high-density display that can make Studio a joy to use. Genero 3.20 introduced a new server synchronisation mode, where code is kept in sync between the local Studio installation and the server.  This makes local development much more efficient.  Also, by utilising the development licenses on the server, there is no need to worry about licensing individual workstations. This article explores several options to aid setting up a portable, productive and secure remote development environment using Genero 3.20, suitable for using over a WAN.

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Informix Forest of Trees Indexes2021-06-07T17:08:01+01:00

Abstract

The IBM Informix Dynamic Server (IDS) documentation page here gives this introduction: “A forest of trees index is like a B-tree index, but it has multiple root nodes and potentially fewer levels. Multiple root nodes can alleviate root node contention, because more concurrent users can access the index. A forest of trees index can also improve the performance of a query by reducing the number of levels involved in buffer read operations.” If your system has any indexes accessed by large numbers of users simultaneously, and if CPU usage is higher than expected, you might try replacing those most affected with FOT indexes. There are defects and caveats, so this should only be done when essential and after careful analysis.

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Informix Partition Defragmentation2021-06-07T17:11:42+01:00

Abstract

From Informix Dynamic Server (IDS) 11.70, syntax exists to merge extents for any table or index, even system catalog tables for which there was previously no solution. This article examines why it matters and provides methods to defragment any number of them in one run.

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Informix Upgrades and “oncheck”2021-06-07T17:12:07+01:00

Abstract

There is a standard recommendation to scan tables and indexes using the Informix “oncheck” tool for any integrity issues before an in-place database server upgrade that might otherwise make it fail. What is less well known is that it should be run afterwards in case problems have been caused by the upgrade. This article covers a specific scenario where this is necessary and how it can be more easily resolved.

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Informix Connection Logging2021-02-16T15:58:43+00:00

Abstract

There is no built-in way to view the history of connections to an IBM Informix Dynamic Server (IDS) database once they have terminated. Doing so can be the key to solving questions such as where a user is located or who has been performing particular SQL actions, whether it be for auditing, application improvement, or user training. This article outlines a simple solution that can be implemented to append connection details to an external text file as a permanent record, and goes further to describe how that can then be maintained and accessed with SQL.

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Informix 14.10 Manage Shared Memory Dumps2020-08-18T10:30:40+01:00

Abstract

Informix Dynamic Server (IDS) can be configured to save the contents of shared memory (as well as readable evidence in an “assert file” and stack trace) either when a critical error occurs or a trap is in place for specific error numbers. This can help IBM diagnose a problem by running “onstat” commands off-line to examine the state at time of error. However, if dumps happen repeatedly before the DBA can intervene, the file system nominated to store them may well fill. Saving a memory dump is also slow, intensive, and exclusive, so excessive repeats will further impede the instance, assuming it has stayed running, and if not will hinder any restart attempts until the dump has finished. Managed Shared memory dumps is the latest configuration parameter settings in IDS 14.10.FC4 that enable limiting the number and/or frequency of such dumps. These enhancements are described in the updated documentation pages for DUMPSHMEM and DUMPCNT in the IBM Knowledge Center, but are missing from What’s New in IDS 14.10 so may not be as well known.

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