Updating tables in a database
Indexes only have individual free space maps and don't have visibility map. The naming method for version-specific one is shown below.
A specific example is shown below: $ cd $PGDATA $ ls -la base/16384/18751* -rw------- 1 postgres postgres 8192 Apr 21 base/16384/18751 -rw------- 1 postgres postgres 24576 Apr 21 base/16384/18751_fsm -rw------- 1 postgres postgres 8192 Apr 21 base/16384/18751_vm They may also be internally referred to as the forks of each relation; the free space map is the first fork of the table/index data file (the fork number is 1), the visibility map the second fork of the table's data file (the fork number is 2). A tablespace in Postgre SQL is an additional data area outside the base directory. Figure 1.3 shows the internal layout of a tablespace, and the relationship with the main data area. If you create a new table which belongs to the database created under the base directory, first, the new directory, whose name is the same as the existing database OID, is created under the version specific subdirectory, and then the new table file is placed under the created directory.
By utilizing the SQL Server geometry and geography data types, SQL stored procedures, and triggers, we can essentially bypass the Esri Arc SDE stack and push attribute and spatial updates directly to nonversioned feature class tables.
Simple to complex insertions and updates can be performed through SQL, allowing us to provide (upon map refresh or redraw) instant feature class updates to end users.
A (heap) table is a typical example of it, and there are many more like an index, a sequence, a view, a function and so on. All the database objects in Postgre SQL are internally managed by respective object identifiers (OIDs), which are unsigned 4-byte integers.
In Postgre SQL, databases themselves are also database objects and are logically separated from each other. The relations between database objects and the respective OIDs are stored in appropriate system catalogs, depending on the type of objects.
A Postgre SQL server runs on a single host and manages a single database cluster.
Internal layout of pages depends on the data file types. To identify a tuple within the table, tuple identifier (TID) is internally used. In addition, heap tuple whose size is greater than about 2 KB (about 1/4 of 8 KB) is stored and managed using a method called TOAST (The Oversized-Attribute Storage Technique). Suppose a table composed of one page which contains just one heap tuple. When the second tuple is inserted, it is placed after the first one. TID-Scan is a method that accesses a tuple directly by using TID of the desired tuple.Real-time data is becoming more and more prevalent in the world around us and therefore in greater demand within GIS applications.So how can real-time data be pushed to an Arc SDE geodatabase?Pushing real-time data into an Arc SDE geodatabase for immediate consumption by end users can be challenging.However, with the advent of Microsoft's SQL Server 2008 and Esri support for the built-in SQL Server 2008 spatial data types, real-time updating of Arc SDE feature classes in SQL Server 2008 has gotten easier.