Database Spec
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Truly embedded ADO.NET 2 SQL database for .NET 2+, CF 2 and Mono
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Less than 1 MB single assembly deployment
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Cross-platform Windows, Linux and Mac OS X support using the Mono Project
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Easy migration from SQL Server TSQL
Royalty-free distribution |
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VistaDB 3 Engine Features
- .VDB3 databases are single-file databases (or data stores)
that contain all the data for a given database
- VistaDB Data types are highly compatible with SQL Server 2005 (See:
Data Types for more)
- TSQL parser highly compatible with SQL Server 2005 syntax and functions
- VDB3 databases store rich data types while ensuring a
high-degree of data integrity
- Multiple .VDB3 database files may be created and
simultaneiously opened
- .VDB3 database files can be opened in 5 different modes:
- Exclusive Read-Write
- Exclusive Read Only
- Non-Exclusive Read-Write
- Non-Exclusive Read Only
- Shared Read Only
- .VDB3 database may be copied as you would any regular
file
- File copy command can be used to backup a VistaDB database
file.
- 4TB of data per database
- 65,535 tables per database, 65,535 columns per table and
65,535 indexes per table
- Blowfish encryption key can be 8 to 56 characters with the
VistaDB engine implementing 16 iterations of encryption using the key
- Database, table and column level encryption supported
- Compression may be applied to character and binary type
columns
- Dynamically set default values when records are added or
modified with static values or V-Script function results
- Primary and Foreign keys supported
- Indexes support case insensitive and case sensitivity,
ascending and descending flags
- Indexes are automatically compressed
- Default values
- Configureable page size in the database file to optimize data
access depending on type of data being stored
- Automatic best-fit block size allocation for Binary and Text
type data
- Constraints
- Relationships (via Primary and Foreign keys)
- Columns may be marked as read-only and hidden
- Columns may be assigned captions and descriptions
- Tables and columns support descriptions
- NewID() function support for UniqueIdentifier and character
type columns
- Native 64 bit support on Windows x64 platforms
- No CPU or RAM usage limitations imposed by the engine
- Full-Text Search indexes in VarChar, Character and Memo fields
- CLR Triggers - C# or VB.Net custom code called during update, delete or insert operations
- CLR Procs - C# or VB.Net Stored Procedures and User Defined Functions
Features that will be added in 3.x releases (see roadmap):
- T-SQL stored procs (VistaDB supports native CLR Procs today)
- MS Sync Services Support
- Client / Server Support
- LINQ Entity Framework provider support
VistaDB 3.x Data Types compared to TSQL
| SQL Server 2005 |
VistaDB 3.3 |
VistaDB 2.x |
.NET System |
| BigInt |
BigInt |
Int64 |
Int64 |
| Bit |
Bit |
- |
Byte |
| Bit |
Bit |
Boolean |
Boolean |
| Char |
Char |
Character |
String |
| DateTime |
DateTime |
Date |
DateTime |
| DateTime |
DateTime |
DateTime |
DateTime |
| Decimal |
Decimal |
- |
Decimal |
| Float |
Float |
Double |
Double |
| Identity Fields |
Identity Fields |
AutoIncrement |
- |
| Image |
Image |
BLOB |
Byte[] |
| Image |
Image |
Picture |
Byte[] |
| Int |
Int |
Int32 |
Int32 |
| Money |
Money |
Currency |
Decimal |
| NChar |
NChar |
- |
String |
| NText |
NText |
- |
String |
| NVarchar |
NVarchar |
- |
String |
| Real |
Real |
- |
String |
| SmallDateTime |
SmallDateTime |
|
Int16 |
| SmallInt |
SmallInt |
- |
Int16 |
| SmallMoney |
SmallMoney |
- |
Decimal |
| Text |
Text |
Memo |
String |
| Timestamp |
Timestamp |
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Int64 |
| TinyInt |
TinyInt |
- |
Byte |
| UniqueIdentifier |
UniqueIdentifier |
Guid |
Guid |
| Binary |
(use varbinary) |
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| VarBinary |
VarBinary |
- |
Byte[] |
| VarChar |
VarChar |
Varchar |
String |
| XML |
- |
- |
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VistaDB 3.x Database Specifications and Limits
| Maximum |
Details |
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# of Columns in a Table |
1,024
This applies to all column types. |
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# of Columns in an Index Key |
256 |
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# of Indexes in a Table |
Primary indexes per table: 1
Secondary
indexes per table: Unlimited
Increasing the number of secondary indexes
may affect performance since the engine must update all indexes when row
changes are applied. |
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# of Rows in a Table |
4,294,967,293
VistaDB uses an unsigned 32-bit integer RowId
to address physical records. When a record is deleted, the respective RowId
doesn't participate in further table modifications, and the record apartment is
put into re-cycling. RowId's get re-assigned to records when a database is
packed. |
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# of Rows in a Transaction |
Limited only by available memory constraints
of the operating system or hardware.
Transactions use multi-versioning record
schema. New record versions are allocated for each transaction.
|
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# of Tables in a Database |
2,147,483,646 In reality, the limit is based on
available memory constraints of the operating system or hardware. |
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Size of Database File |
4TB per .VDB3 database file
Theoretical limit is 16 Exabytes. |
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Size of Index Database Objects |
Page size / 4
Objects are: Database Description, Table Name/Description,
column Name/Description, Index Name, View Name/Description, Constraint
Name/Description etc. |
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Size of Check Constraint Expression and Default Value
Expression |
Page Size / 4 |
| Size of CLR Proc
Signature |
Page size / 4 |
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Size of Assembly COFF-Image |
Depends on Page Size. For example:
1Kb page - 134, 216,
632 bytes
16Kb page - 2, 147, 466, 112 bytes |
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Size of View Expression |
~60,000,000 chars |
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Size of Rows (Records) |
Maximum size approx. the same as the Maximum Size for
Image column divided by 3. For example:
1Kb page ~ 44, 000, 000
bytes
16Kb page ~ 704, 000, 000 bytes |
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Size of Text/NText/Image Columns |
Text/ NText and Image column data is not
stored in the row if their data exceeds 25% of the database page size The
maximum size depends on database page size and code page (for character
columns). For example:
1Kb page - 134, 216, 632 bytes
16Kb page - 2, 147,
466, 112 bytes |
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Transaction Isolation Level |
ReadCommitted
Snapshot isolation |
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Database File Page Size |
1,024 (by default) - 16,384 bytes
Data is read and written by pages. The bigger page, the
more time will be required for I/O operations. At the same time, the rows are
grouped by several instances and aligned within the page boundary. If the pages
size is insufficient to allocate ~3 records, data is expanded and stored to
extra pages. The expansion process takes additional time for I/O and thus, the
more actual data length a record has, the bigger the page size should be. This
Page Size is defined when a database is created. It can be modified later but
must be followed by a Pack operation. |
| Data Deployment Options |
VDB3 files can be custom named, and deployed on a wide variety of media and platforms.
Partial trust - medium trust (shared hosting) environment fully supported.
XCopy deployable - Nothing to install on target machine. No services, no registry access. Can run as Guest on any Windows OS.
Read only - Data may be written to read only media (CD / DVD ROM) and queried live.
LAN - Through the use of mapped drive letters or UNC naming.
USB Key - Data may be stored on any Windows drive (NTFS / FAT / FAT32).
Isolated Storage - VistaDB fully supports creation and running of databases in Isolated Storage.
Memory Backed / VM - Create temp databases that are only backed by Virtual Memory. When the database is closed it is destroyed. |
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Memory Tables |
A database created in memory. The size is limited only by
available memory constraints of the operating system or hardware.
Memory Tables and Memory Databases follow the same
restrictions and constraints as physical tables and databases. |
Self Imposed Limits (** where noted)
VistaDB was designed using 32-bit and 64-bit
memory addressing in most situations that required large upper limits. The
effect of supporting large upper limits are ranges that exceed 4 billion or 4GB
for 32-bit values and provides massive Exabytes limits for 64-bit values.
Because of our focus on supporting the creation of small to midsize
applications, supporting such enormous upper limits is not feasible for
testing. Therefore we have implemented some self-imposed limits in some
places.
Setting Default Values
VistaDB allows you to dynamically set default values when new
records are added, or optionally when they are modified, using pre-defined
functions. With this feature, you can generate a wide range of data settings
based on the existing data types. For example, you can use the GUID() function
to generate unique GUID values and "version control" table records, or use the
NOW() function to stamp new records with the current Date and Time.
Nunit Tests and Coverage Reports Included
We include over 420 NUnit tests with our application to demonstrate our commitement to quality. We also include the reports of our code coverage tests to show our progress in testing the engine. Our goal is to reach 80% code coverage in each module. We are not there yet, but we are working on it.
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