- A relational database is a collection of data items with pre-defined relationships between them. These items are organized as a set of tables with columns and rows. Tables are used to hold information about the objects to be represented in the database.
- Database, any collection of data, or information, that is specially organized for rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval, modification, and deletion of data in conjunction with various data-processing operations.
- A database is a computerised system that makes it easy to search, select and store information. Databases are used in many different places. Your school might use a database to store information.
- Database definition is - a usually large collection of data organized especially for rapid search and retrieval (as by a computer). How to use database in a sentence.
- What Is Database Io
- What Is Database Software
- What Is Database Schema
- What Is Database Experience
- What Is Database Index
- What Is Database Management System
- What Is Database Management
A database is an organized collection of structured information, or data, typically stored electronic.
MEDLINE is the U.S. National Library of Medicine® (NLM) premier bibliographic database that contains more than 26 million references to journal articles in life sciences with a concentration on biomedicine. A distinctive feature of MEDLINE is that the records are indexed with NLM Medical Subject Headings (MeSH®). MEDLINE is the online counterpart to MEDLARS® (MEDical Literature Analysis and Retrieval System) that originated in 1964.
The great majority of journals are selected for MEDLINE based on the recommendation of the Literature Selection Technical Review Committee (LSTRC), an NIH-chartered advisory committee of external experts analogous to the committees that review NIH grant applications. Some additional journals and newsletters are selected based on NLM-initiated reviews, e.g., history of medicine, health services research, AIDS, toxicology and environmental health, molecular biology, and complementary medicine, that are special priorities for NLM or other NIH components. These reviews generally also involve consultation with an array of NIH and outside experts or, in some cases, external organizations with which NLM has or had special collaborative arrangements.
MEDLINE is the primary component of PubMed®, part of the Entrez series of databases provided by the NLM National Center for Biotechnology Information (NCBI).
Time coverage: MEDLINE includes literature published from 1966 to present, and selected coverage of literature prior to that period. See OLDMEDLINE Data for coverage details about the pre-1966 citations that are not comprehensive for that time period.
Source: Currently, citations from more than 5,200 worldwide journals in about 40 languages; about 60 languages for older journals.
Updates: Citations are added to PubMed 7 days a week. More than 956,390 citations were added to MEDLINE in 2019. Updates are suspended for two weeks during November as NLM makes the transition to a new year of Medical Subject Headings (MeSH) vocabulary used to index the articles.
Broad subject coverage: The subject scope of MEDLINE is biomedicine and health, broadly defined to encompass those areas of the life sciences, behavioral sciences, chemical sciences, and bioengineering needed by health professionals and others engaged in basic research and clinical care, public health, health policy development, or related educational activities. MEDLINE also covers life sciences vital to biomedical practitioners, researchers, and educators, including aspects of biology, environmental science, marine biology, plant and animal science as well as biophysics and chemistry. Increased coverage of life sciences began in 2000. Privatus 6 0 – automated privacy protection act.
The majority of the publications covered in MEDLINE are scholarly journals; a small number of newspapers, magazines, and newsletters considered useful to particular segments of the NLM broad user community are also included. For citations published in 2010 or later, over 40% are for cited articles published in the U.S., about 93% are published in English, and about 85% have English abstracts written by authors of the articles.
Availability: MEDLINE is the primary component of PubMed (//pubmed.gov); a link to PubMed is found on the NLM homepage (//www.nlm.nih.gov). The result of a MEDLINE/PubMed search is a list of citations (including authors, title, source, and often an abstract) to journal articles and an indication of free electronic full-text availability. Searching is free of charge and does not require registration.
A growing number of MEDLINE citations contain a link to the free full text of the article archived in PubMed Central® or to other sites. You can also link from many MEDLINE references to the Web site of the publisher or other full text provider to request or view the full article, depending upon the publisher's access requirements.
Access to MEDLINE data are also available via services and products developed by organizations that download the database from NLM. Access to various MEDLINE services is often available from medical libraries, many public libraries, and commercial sources.
MedlinePlus®, another service offered by the NLM, provides consumer-oriented health information. Health consumers are encouraged to discuss search results with their health care provider.
For further information about MEDLINE contact NLM customer service or call toll-free 1-888-346-3656. For the nearest local medical library in your area contact the Network of the National Library of Medicine (NNLM) at 1-800-338-7657.
Related Publications and Resources:
Hands off 3 1 1 download free. See also the MEDLINE/PubMed Resources Guide.
Sample Record: PubMed Abstract display
Sample Record: PubMed MEDLINE display
Filename extension | |
---|---|
Developed by | Microsoft |
Type of format | Debug |
Program database (PDB) is a proprietary file format (developed by Microsoft) for storing debugging information about a program (or, commonly, program modules such as a DLL or EXE). PDB files commonly have a .pdb extension. A PDB file is typically created from source files during compilation. It stores a list of all symbols in a module with their addresses and possibly the name of the file and the line on which the symbol was declared. This symbol information is not stored in the module itself, because it takes up a lot of space.
Applications[edit]
When a program is debugged, the debugger loads debugging information from the PDB file and uses it to locate symbols or relate current execution state of a program source code. Microsoft Visual Studio uses PDB files as its primary file format for debugging information.
Another use of PDB files is in services that collect crash data from users and relate it to the specific parts of the source code that cause (or are involved in) the crash.
Microsoft compilers will, under appropriate options, store information in a single PDB about types found in the compiled sources. Debug information specific to each source is stored in the compiled object file, and contains references to types in the PDB. Each compilation will add to the PDB any types that are not already found there, so that references in already compiled object files remain valid.
The Microsoft linker, under appropriate options, builds a complete new PDB which combines the debug information found in its input modules, the types referenced by those modules, and other information generated by the linker. If the link is performed incrementally, an existing PDB is modified by adding replacing only the information pertaining to added or replaced modules, and adding any new types not already in the PDB.
PDB files are usually removed from the programs' distribution package. They are used by developers during debugging to save time and gain insight.
Extracting information[edit]
The PDB format is documented here, information can be extracted from a PDB file using the DIA (Debug Interface Access) interfaces, available on Microsoft Windows. There are also third-party tools that can also extract information from PDB such as radare2 and pdbparse
Multiple stream format[edit]
The PDB is a single file which is logically composed of several sub-files, called streams. It is designed to optimize the process of making changes to the PDB, as performed by compiles and incremental links. Streams can be removed, added, or replaced without rewriting any other streams, and the changes to the metadata which describes the streams is minimized as well.
The PDB is organized in fixed-size pages, typically 1K, 2K, or 4K, numbered consecutively starting at 0.
Note: It is presumed that all numeric information (e.g., stream and page numbers) is stored in little-endian form, the native form for Intel x86 based processors. The pdbparse Python code makes this assumption.
Stream[edit]
Each stream in the PDB occupies several pages, which aren't necessarily consecutively numbered. The stream has a number and a length. The stream content is the concatenation of its pages, truncated to the stream's length.
Metadata format[edit]
The function of the PDB metadata is to identify all of the component streams, giving the length, and sequence of pages for each stream. Barcody 2 12 – barcode generator with linkback support. Streams are numbered consecutively starting with 0. There is also a root stream, unnumbered, which contains some of the metadata.
Header[edit]
The PDB begins with a header, consisting of:
- Signature, used to identify and validate the specific format. The length of the signature varies with the specific format.
- The remainder of the header varies with the format identified by the signature.
The header may be longer than a single page.
What Is Database Io
Microsoft tools use two PDB formats:
Version 7[edit]
Signature is
'Microsoft C/C++ MSF 7.00rnx1ADS000'
(32 bytes).Remainder of the header consists of:
- Page size, 4 bytes.
- Allocation table pointer, 4 bytes. The meaning of this is unknown. There appears to be an allocation table, an array of 65,536 bits (8,192 bytes), located at the end of the PDB, and a 1-bit means a page that is not being used.
- Number of file pages, 4 bytes.
- Root stream size, 4 bytes.
- reserved, 4 bytes.
- Page number of the Root stream page number list. It does not indicate the location of the Root stream itself, only of the page containing the structure which points to its pages. At that page, the Root stream page number list indicates the pages where the Root stream is stored. It contains 4 bytes per page, enough to cover the above Root stream size.
Root stream[edit]
The root stream describes all of the PDB streams starting with stream 0. Its contents vary with the PDB format version.
Version 2[edit]
The root stream consists of:
- Number of streams, 2 bytes.
- Reserved, 2 bytes.
- For each stream:
- Stream size, 4 bytes.
- Reserved, 4 bytes.
- For each stream:
- Stream page number list, 2 bytes per page, enough to cover above stream size.
Version 7[edit]
What Is Database Software
The root stream consists of:
What Is Database Schema
- Number of streams, 4 bytes.
- For each stream:
- Stream size, 4 bytes.
- For each stream:
- Stream page number list, 4 bytes per page, enough to cover above stream size.
![What What](https://image.slidesharecdn.com/database-111011024112-phpapp02/95/importance-of-database-in-library-2-728.jpg?cb=1318301843)
Stream contents[edit]
Microsoft tools store different sorts of information in different numbered streams. Some stream numbers have a fixed information type associated with them, and other streams are identified in the aforementioned fixed type streams.
Stream 1 is used to verify that the PDB is the same file referred to in an executable or object file stream.
What Is Database Experience
- Version, 4 bytes.
- Time date stamp, 4 bytes.
- Age, 4 bytes. This is the number of times this PDB has been modified since its creation.
- GUID, 16 bytes.
- Total length of following names, 4 bytes. Followed by null-terminated character strings.
Stream 2 and stream 4 hold types information. Actual type records define types used in the program. The structure of these records can be found in the file cvinfo.h provided by Microsoft. There are two flavors of records, each with its own set of index numbers: type IDs and types; only types are stored in stream 2 and only type IDs are stored in stream 4. The indices are used to refer to these records from within symbol records and other type records.
- A header:
- Version, 4 bytes.
- Header size, 4 bytes.
- Minimum and maximum (last + 1) index for type records (4 bytes each).
- Size of following data, 4 bytes, to the end of the stream.
- Hash information:
- Stream number, 2 bytes with 2 bytes padding.
- Hash key, 4 bytes.
- Buckets, 4 bytes.
- HashVals, TiOff, and HashAdj, each composed of an offset and length, each 4 bytes.
- Type records, variable length, count = (maximum - minimum) from above header.
Stream 3 is a directory for other streams. Note, it is not present in Version 2, nor in a PDB produced by a compiler. The stream starts with a header which is padded to be 64 bytes in total
Offset | Size | Name | Description |
---|---|---|---|
0 | 4 | Signature | Header identifier, 0xFFFFFFFF |
4 | 4 | HeaderVersion | Version of the Header |
8 | 4 | Age | |
12 | 2 | snGSSyms | |
14 | 2 | usVerAll | |
16 | 2 | snPSSyms | |
18 | 2 | usVerPdbDllBuild | build version of the pdb dll that built this pdb last |
20 | 2 | snSymRecs | |
22 | 2 | VerPdbDllRBld | rbld version of the pdb dll that built this pdb last |
24 | 4 | cbGpModi | size of rgmodi substream |
28 | 4 | cbSC | size of Section Contribution substream |
32 | 4 | cbSecMap | size of section map |
36 | 4 | cbFileInfo | size of file info stream |
40 | 4 | cbTSMap | size of the Type Server Map substream |
44 | 4 | iMFC | MFC Index |
48 | 4 | cbDbgHdr | size of optional DbgHdr info appended to the end of the stream |
52 | 4 | cbECInfo | number of bytes in EC substream, or 0 if no EC enabled Mods |
56 | 2 | flags | |
58 | 2 | wMachine | Machine identifier, same as used in COFF object format, e.g., hex 8664 for Intel x86 64-bit |
60 | 4 | RESERVED | future expansion, pad to 64 bytes |
- Module information, variable length. Total size in above header. There is one of these for each object module used by the linker
- Opened, 4 bytes.
- Symbol info.
- Section number, 2 bytes + 2 bytes padding.
- Offset and size, 4 bytes each.
- Flags, 4 bytes.
- Module number, 2 bytes + 2 bytes padding.
- CRCs for section data and relocations data, 4 bytes each.
- Flags, 2 bytes.
- Stream number, 2 bytes.
- Symbols size, 4 bytes.
- Old and new line number info sizes, 4 bytes each.
- Number of source files, 2 bytes + 2 bytes padding.
- Offsets, 4 bytes.
- niSource and niCompiler, 4 bytes each.
- Module name, null terminated byte string.
- Object name, null terminated byte string.
- Padding to multiple of 4 bytes.
- Section contributions, section headers, file info, ts map, and EC info. Their sizes are found in the above header.
- Debug header,
- Stream numbers for Old Frame Pointer Omission, Exceptions, Fixups, Object Maps to and from Source, Section Headers, Token Ring IDs, Xdata, Pdata, New Frame Pointer Omission, and Section Header Origin. 2 bytes each.
What Is Database Index
See also[edit]
What Is Database Management System
External links[edit]
What Is Database Management
- The PDB format is documented here Information from Microsoft about the PDB format.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Program_database&oldid=963497026'