1. About YottaDB¶
YottaDB® is a high-end performance database application development and deployment platform from YottaDB LLC. YottaDB provides an M language subsystem, a database engine, and a complete set of utilities for administration and operation. One can install and manage YottaDB using the utilities described in this manual and standard operating system tools. This chapter provides an overview of the YottaDB system environment and utilities.
Hardware/ Operating System Environment¶
YottaDB runs on a variety of UNIX/Linux implementations. Consult YottaDB for currently supported versions. Each YottaDB release is extensively tested by YottaDB on a set of specific versions of operating systems on specific hardware architectures (the combination of operating system and hardware architecture is referred to as a platform). This set of specific versions is considered “supported”. There will be other versions of the same operating systems on which a release may not have been tested, but on which the support team knows of no reason why YottaDB would not work. This larger set of versions is considered “supportable”. There is an even larger set of platforms on which YottaDB may well run satisfactorily, but where the support team lacks the knowledge to determine whether YottaDB is supportable. These are considered “unsupported”. Contact YottaDB Support with inquiries about your preferred platform.
System requirements vary widely depending on application needs, and should be empirically determined for each situation.
The 32-bit version of YottaDB is compiled to require the 586 (“Pentium compatible”) instruction set.
YottaDB installation is semi-automatic, using the ydbinstall script provided with the product. The installation procedure is described in Chapter 2: “Installing YottaDB”.
Users require no special privileges to run YottaDB beyond standard system access and suitable access to relevant application and database files. All standard UNIX security features are available to protect YottaDB resources.
YottaDB strongly recommends a security design where each user has no more authorizations than they require to do their assigned roles and each user’s actions are distinguishable in an audit.
Root or superuser access is required to install YottaDB, but not to use it. YottaDB recommends against routine use of the root userid to run YottaDB.
Program Development Environment¶
YottaDB provides a compiler and run-time environment for the M language. Program development uses standard editors and utility programs.
YottaDB requires minimal administrative effort.
M routines are stored as text files and object files in the native file system. Compilation of source text into object code is typically automatic, but may be invoked explicitly. A user may store routines in multiple libraries and/or directories organized into search hierarchies, and change the search paths as needed.
For more information on the YottaDB language and programming environment, see the Programmer’s Guide.
The YottaDB database subsystem consists of a run-time library and a set of utilities which operate on one or more user-specified Global Directories (GD) and database files. YottaDB stores M global variables in database files, which are ordinary UNIX files. Internally, the UNIX files are organized as balanced trees (B-trees) in YottaDB Data Structures (GDS). See the “YottaDB Database Structure” chapter for more information on B-trees and the GDS file structure.
A directory maps global names to a database file. YottaDB processes use this mapping when storing and retrieving globals from the database. Multiple global directories can reference a single database file, and a database file can be referenced in multiple global directories, with some exceptions, as discussed in Chapter 4: “Global Directory Editor”. Use the Global Directory Editor (GDE) to create and maintain global directories.
In addition to mapping global variables to database files, global directories also store initial parameters used by the MUPIP CREATE command when creating new database files. YottaDB uses environment variables to locate the global directory or, optionally database files.
YottaDB Utility Programs¶
YottaDB provides utility programs to administer the system. Each utility is summarized below, and described later in this manual.
The Global Directory Editor (GDE) is a YottaDB utility program that creates and maintains global directories. GDE provides commands for operating on the global directory.
MUPIP (M Peripheral Interchange Program) is the YottaDB utility program for general database operations, YottaDB Journaling, Multi-site Database Replication, and some non-database operations.
The M Lock Utility (LKE) is the YottaDB utility program that examines and modifies the lock space where YottaDB maintains the current M LOCK state. LKE can monitor the locking mechanism and remove locks. See Chapter 8: “M Lock Utility (LKE)” for more information.
The Database Structure Editor (DSE) is the YottaDB utility program to examine and alter the internal database structures. DSE edits YottaDB Database Structure (GDS) files. It provides an extensive database “patch” facility (including block integrity checks), searches for block numbers and nodes, and provides symbolic examination and manipulation facilities. See Chapter 10: “Database Structure Editor” for more information.
5. Command Qualifiers¶
Each utility program has its own set of commands. Qualifiers are used as arguments for a command. A qualifier is always prefixed with a hyphen (-). Some qualifier allow assigning values with an equal (=) sign where as some allow the use of sub-qualifiers as their arguments. If you specify the same qualifier more than once, MUPIP, DSE, and LKE acts upon the qualifier that appears latest. However, you cannot specify qualifiers that have sub-qualifiers more than once. With GDE, specifying the same qualifier more than once produces an error.
YottaDB tools verify and maintain database integrity. As described in Chapter 11: “Maintaining Database Integrity”, database integrity refers to a state of logical and physical consistency in the database when all of the globals and pointers are correct, thereby making all data accessible. Chapter 11 describes how to use the MUPIP INTEG command and the DSE utility to detect and repair integrity problems, and supplies procedures for avoiding such problems.
YottaDB uses UNIX Interprocess Communication (IPC) resources to coordinate access to the database. Additionally, YottaDB includes a daemon process gtmsecshr that implements process wake-up for M locks and clean-up of IPC resources after certain types of abnormal process termination. See Appendix A: “YottaDB’s IPC Resource Usage” for more information.