Informix 12 new features.

https://www.ibm.com/developerworks/community/blogs/idsteam/entry/restoring_critical_administrative_files_with_onbar_utility?lang=en

Starting with Informix vesion 12.10.xC2, you can restore the critical files that you backed up with onbar utility. Onbar cold restore has an option now to restore these files or you can only restore these file without perform the storate space restore.

Use ‘onbar -r -cf yes’ to restore critical file during cold restore. Alternatively, you can use ‘onbar -r -cf only’ to extract critical files while Informix server is offline.

https://www.ibm.com/developerworks/community/blogs/idsteam/entry/monitor_resource_contention?lang=en

Two new onstat commands introduced in 12.10.xC2 to view the dependencies between blocking and waiting threads.

Now, you can use the ‘onstat -g bth’ command to display the dependencies between blocking and waiting threads. Next, use the ‘onstat -g BTH’ command to display session and stack information for the blocking threads.

https://www.ibm.com/developerworks/community/blogs/idsteam/entry/after_an_upgrade_query_running_slow?lang=en

A newer costing functionality was added in 11.70.FC3 and higher in the 11.70 family. This functionality was added to account for the seek time required to traverse an index (especially large indexes). There were situations where queries using an index would take longer to return than a sequential scan because of all the I/O involved.

You can control the new costing functionality using the OPT_SEEK_FACTOR configuration parameter. This parameter allows to set the “weight” of an I/O seek cost. The range is 0 to 25 and default is 6. Making it lower causes the seek cost to be lower which lowers the estimated cost of using an index path.

You can revert to the old costing method by setting OPT_SEEK_FACTOR to 0 in the ONCONFIG file.

https://www.ibm.com/developerworks/community/blogs/idsteam/entry/why_dbaccess_always_query_dns_server_while_connecting_to_a_database?lang=en

Traditionally, hostname and service name resolution were performed by functions such as gethostbyname(), getservbyname() etc. These traditional lookup functions are still available, however those are not forward compatible to IPv6. Instead, the IPv6 socket API provides new lookup functions that consolidate the functionality of several traditional functions. These new lookup functions are also backward compatible with IPv4, so a programmer can use the same translation algorithm in an application for both the IPv4 and Ipv6. The getaddrinfo() is the new primary lookup function and a connection request from the dbaccess ultimately calls this socket API. You can pass several parameters to the getaddrinfo(), one of those parameter is addrinfo structure. By default, dbaccess passes value “AF_INET6” for addrinfo.ai_family. The ai_family field indicates the protocol family associated with the request, and will be PF_INET6 for IPv6 or PF_INET for IPv4.

If the ai_family set to AF_INET6 (IPv6) the getaddrinfo() will search the DNS everytime. If the ai_family set to AF_INET, then it don’t query the DNS server. You can consult the ‘man’ page for getaddrinfo() for detailed information.

Beginning with Informix 10.00.xC4 and Client SDK 2.90.xC4, the database server checks, on startup, whether IPv6 is supported in the underlying operating system. If IPv6 is supported it is used. If the underlying operating system does not support IPv6, the IPv4 address is used.

In case of a problem with DNS lookup and encountering slow connection to databse, you may use the environment variable IFX_DISABLE_IPV6 (IFX_DISABLE_IPV6=1) to disable Ipv6 and this will set the ai_family to AF_INET only and will not do subsiquent query to the DNS server.

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