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Category: ASE: Data Storage
Global allocation map pages, GAM pages
Every
database
has at least one Global Allocation Map Page or GAM page.
This page contains a
bitmap
for all
allocation units
in the database. Each allocation unit is represented by one bit on the GAM page.
If an allocation unit has no more free
extents
to maintain further
objects,
the corresponding
bit
on the Global Allocation Map is set to 1. This accelerates
allocating additional storage space for objects.
For normal
users
the Global Allocation Map is not visible. GAM pages can be queried via the
system table
sysgamps.
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