Deciding to work with Linked or Live Access Tables - MapInfo_Pro - 2023

MapInfo Pro Help

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MapInfo Pro Help
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Last updated
2023-09-12
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2023-09-12T16:39:16.995549

There are two ways in which you can work with your data tables: live (or live with caching) and linked. If you are not working with very much data, a small data table size, then it does not matter if you choose to work with live or linked access.

About Live Access Tables

You can access remote data as a live access table using MapInfo Pro. It is called a live access because there is no local copy of the data, that is, all operations against the data go directly to the server. This differs from linked tables, which download a snapshot from the remote database into a native MapInfo Pro table.

You can perform most operations on a live access table that you do for a regular MapInfo Pro table. For example, you can view, edit, copy, and save a live access layer just as you can a regular MapInfo Pro table. However, you cannot pack or modify a live access table's structure.

Live with cache is the preferred way to access live tables. MapInfo Pro provides smart caching to improve performance of live data access from remote databases. During a pan operation, MapInfo Pro retrieves map data from a cache rather than retrieve it from the server every time. Only when the pan requires map data not already contained in the cache, does it go to the server. Closing or refreshing the table clears the cache.

When the live access table is creating a new Map window, the initial view is determined by the entry in the MapInfo_MapCatalog table. The values in the VIEW_* columns, if they exist, describe a rectangular area that is the initial map display. If the live access table is being added as a layer to an existing Map window, the layer will be fit to that Map window.

MapInfo Pro stores information about a live access table in a TAB file. This information is known as metadata. MapInfo Pro uses metadata to store information about the live access table that is needed to manage transactions between MapInfo Pro and the server database. Two of the most important kinds of information stored in the metadata include the connection string and the query you build from the DBMS Table Wizard, or Expert dialog box.

About Linked Tables

A linked table is a MapInfo Pro table that is a replica of a table downloaded from a remote database and retains links to its remote database table. (The remote database table is known as a DBMS table.) When MapInfo Pro downloads a table, it copies the entire contents of the table to the local machine. Any changes you make to the copy can be committed to the server table at any time.

Linked tables can be used stand-alone or remain linked to the original server database. You can refresh linked tables to rerun queries on a regular basis on the TABLE tab, in the Maintenance group, click Database, and Refresh DBMS Table. After editing data in a linked table, MapInfo Pro saves it to the RDBS in a manner that resolves any multi-editing conflicts. Saving the edits made to a linked table commits them to the server database as well as to the linked table.