Dear Colleagues, if I remember correctly, then the directory structure of PDSEs was designed to speed up finding specific members as opposed to listing the entire directory.
To my best of knowledge the directory structure of PDSs is sequential (ordered list) while for PDSEs it is hierarchical (tree-based). Theoretically, finding a specific member should therefore result in linear (O(n)) effort for PDSs and logarithmic effort (O(log n)) for PDSEs. Does anybody have any measurements on that and would like to share it with us? I guess the main purpose of PDSEs is to serve as program libraries and in many cases doing this in library concatenations, which are searched for specific programs by the loader. On the contrary it is not obvious for me, which use case requires listing a directory of 25K to 30K members efficiently, but maybe you can update me on that. The bad directory listing performance probably stems from the index pages being scattered across the entire PDSE instead of being nicely ordered at the beginning of the dataset. Does copying and thus defragmenting the library also reorganize the index pages? Kind regards Gerald Scharitzer ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
