Query Execution

Materialized Model

Queries are defined in Microsoft QBE (Query By Example) through the Microsoft Access SQL Window. These queries are then converted to SQL Select statement queries. These SQL queries are then compiled and converted into an internal Jet query object format, which is a tree-like structure. Finally, the system executes the query and return the result.

Views

Not Supported

Views are not supported in MS Access.

Storage Architecture

Disk-oriented

Microsoft Access can scaled to enterprise-level solutions by linking to multiple databases on disk or using a back-end database like Microsoft SQL Server.

Logging

Not Supported

Query Compilation

JIT Compilation

They incorporate Fox's Rushmore query optimization routines into Access.

Data Model

Relational

Access tables support a variety of standard field types, indices, and referential integrity including cascading updates and deletes.

Foreign Keys

Supported

Foreign keys are not enforced in Access, they are important constraints that can be used to enforce data integrity in Access.

Concurrency Control

Multi-version Concurrency Control (MVCC)

MS access supports coarse-grained MVCC. In a multi-user scenario, the application will be split. This means that the tables are in one file called the back end (typically stored on a shared network folder) and the application components (forms, reports, queries, code, macros, linked tables) are in another file called the front end. The linked tables in the front end point to the back end file. Each user of the Access application would then receive his or her own copy of the front end file.

Query Interface

Custom API

Access has a query interface, forms to display and enter data, and reports for printing.

Checkpoints

Not Supported

Indexes

B+Tree

Microsoft Access only support B+ tree index.

System Architecture

Embedded

MS Access mainly provides solutions for small-size databases for personal use and uses embedded system architecture.

Storage Model

N-ary Storage Model (Row/Record)

The storage space in Microsoft databases are organized into fixed-length (4 kB in Jet 4) different pages. Data is stored in variable length record, which is less than or equal to page size.

Compression

Bit Packing / Mostly Encoding

By default, Microsoft Access uses unicode compression (which dynamically mapping values in the range 128–255 to offsets within particular blocks of 128 characters) when creating the field via the table properties., all data for the text data types (Text, Memo, or Hyperlink field) are stored in the Unicode 2-byte character format.

Stored Procedures

Supported

VBA (Visual Basic for Application) functions can be written to define any user function in MS Access.

Isolation Levels

Read Uncommitted

Access support multiple isolation levels including Read Uncommitted, Read Committed, Repeatable Read, Snapshot Isolation and Serializable.