vsam

the address directory is removed, and the space to delete the record cannot be rebuilt until the system function is used to reallocate the data set.Extended partitioned Datasets (Pdse: Partitioned Data Set Extended)Similar to the PDS DataSet, it is composed of multiple member, the only difference being that the size of the Pdse address directory is dynamic and does not require the number of directory blocks to be specified when it is created.Therefore, when adding or removing member, the system

must be consistent with the structure of the generating DB2 system, and the test environment must contain a considerable amount of data in order to ensure the accuracy of the test. Two kinds of data cloning technology In general, you can import data into the DB2 system for testing in the following two ways. 1. Use the Unload tool to unload data from the production DB2 system, and then mount the test DB2 environment using the load tool. The advantage of this method is that it is flexible and

also choose open-source database engines to save cost in the future. Developers have many different ways to deal with virtual storage access VSAM) dataset: some simulation VSAM clusters on distributed file systems, you can also convert VSAM file calls to SQL statements by providing some DBMS backend. Transaction processing simulator. Vendors usually provide a C

just talking about DB2 on large hosts. For example, do you know that the DB2 Connect workstation can execute a DB2 for z/OS database and Informix on the Windows database in the same transaction?®Distributed join between IDS. It can also use the built-in two-phase commit (two-phase commit, 2 PC) within the same commit range) to update these data sources. I mentioned that you will find some clever features. This is one of them! If it sounds like Federation, or more like WebSphere®Information Inte

? Ask your accountant what he thinks about the new browser-based accounting software: most commercial users want to use a more friendly Windows user interface.A perfect solution for communication between the client and the server is to use HTTP protocol. This is because any machine running a web browser is using the HTTP protocol. At the same time, many firewalls are configured to only allow HTTP connections.Many commercial applications face another problem: interoperability with other programs.

an open specification built on the ODBC function. ODBC is specially developed to access relational databases. ole db is used to access relational and non-relational information sources, such as the host isam/VSAM and hierarchical database, email and file system storage, text, graphics, and geographic data, as well as custom business objects. Ole db defines a set of COM interfaces, encapsulates various database management system services, and allows y

a data access platform. Here we are not just talking about DB2 on large hosts. For example, do you know that the DB2 Connect workstation can execute a distributed join between a DB2 for z/OS database and Informix IDS on a Windows database in the same transaction ), it can also use built-in support for two-phase commit (two-phase commit, 2 PC) In the same submission scope to update these data sources. I mentioned that you will find some clever features. This is one of them! If it sounds like Fed

the scope of the federated engine to include other relational data sources (Oracle, Microsoft®sql Server), non-relational data sources (Adabas, VSAM), OLE DB, XML, and any other data source in the enterprise. Unified access to heterogeneous distributed data sources You may know what the meaning of Unification (unified), distribution (distributed), and heterogeneous (heterogeneous) means, but it may not be clear how DB2 Connect implements these concep

several ways to do this: Database storage and some data types are proportional, and others are disproportionately growing: We add new data types and apply old (inappropriate) optimization techniques; We use the database in a different way, especially when using the new query pattern, which does not match the old data storage design; Other data stores competing for the same storage on the same disk cause the database to select suboptimal optimized storage. Over time, these tre

During the catalog backup recovery process, the import job terminates abnormally under certain conditions. At this point, catalog will be in a damaged state: The original catalog can not continue to use, import job can not continue. This article mainly introduces an example of such a scene, then restores and proposes how to avoid this anomaly. Catalog for the Zos system is self-evident, so we often need to back up catalog or in the reorganization (reorganize) catalog (because the

deadlocks, and the file system needs to avoid deadlocks. Contact point: Database systems often rely on file systems as their lowest-level storage, and may also implement some file system functions File systems can be specifically optimized for this particular application of the database. The file system can be used as a simple database (e.g. VSAM), and the database can also expose NFS (for example, Oracle) The file system ma

for managing data across the organization. OLE DB is an open specification built on top of the ODBC functionality. ODBC is specifically developed for accessing relational databases, and OLE DB is used to access relational and non-relational sources of information, such as host Isam/vsam and hierarchical databases, e-mail and file system storage, text, graphics and geographic data, and custom business objects.OLE DB defines a set of COM interfaces tha

privately published special diagrams in addition to publicly published ones in Asia, or those specially sent to friends. In addition, they do not want to or do not want to make CSV files, so the CSV files of their Gallery are often made by some senior predecessors in the graph community. In this case, there are usually several versions of CSV files in an gallery, and there is a lot of difference between each version. At this time, CSV is not only the basis for verifying the truth, but also a ho

what he thinks about the new browser-based accounting software: most commercial users want to use a more friendly Windows user interface. A perfect solution for communication between the client and the server is to use HTTP protocol. This is because any machine running a web browser is using the HTTP protocol. At the same time, many firewalls are configured to only allow HTTP connections. Many commercial applications face another problem: interoperability with other programs. If all application

unified data access interface. The "data" mentioned here is not only the data in standard relational databases, it also includes mail data, Web text or graphics, directory services, and IMS and VSAM data in the host system. The core content of the ole db standard requires that these various data storage (datastore) provide the same access interface, so that the data users (applications) you can access various data in the same way without considering

block cannot be placed, you can create an index on the index table, which is called a query table, a second query table, and a third query table. Multi-level indexes are classified into static indexes and dynamic indexes.The indexes at all levels of the static index are ordered, but the index needs to be restructured when it is modified. Therefore, when there are many changes, dynamic indexes are not suitable for static indexes.If the number of file records is small and the index table is not

: The database has much stronger support for transactions, and the file system can only ensure the consistency of metadata. Databases have different levels of consistency, which are reflected in isolation levels. The database can have REDO and UNDO logs. Generally, the file system only uses REDO logs. Database transactions can be very long, and file system transactions are very short. Transactions in the database cannot be determined in advance, but are input by the user. Transactions in t

the HTTP protocol. At the same time, many firewalls are configured to only allow HTTP connections. Many commercial applications face another problem: interoperability with other programs. If all applications are written in the com or. NET language and run on the Windows platform, the world is too peaceful. However, in fact, most commercial data is still stored on large hosts in the form of non-relational files (VSAM) and accessed by mainframe program

database for a long time. The transaction of the file system is very short. The transaction of the database cannot be determined in advance. The transaction of the file system can be determined in advance, A database of a specific type is implemented in the user mode, and a file system is generally implemented in the kernel mode. Therefore, the former is easier to achieve cross-OS platform database access interface is usually not procedural S [this article from the Internet (http://www.68idc.cn

block can hold is more. The more keywords you need to find when you read into memory at once. The number of Io reads and writes is correspondingly lower.For example, suppose that a disk block in a disc holds 16bytes, while a keyword of 2bytes, a keyword specific information pointer 2bytes. An internal node of a 9-order B-tree (a node with a maximum of 8 keywords) requires 2 disks fast. And the B+-tree internal node only needs 1 disks fast. When an internal node needs to be read into memory, the