Inheritance diagram for openzgy.impl.enum.UpdateMode:
Static Public Attributes | |
| int | Never = 0 |
| int | Constant = 1 |
| int | Always = 4 |
| int | Pedantic = 5 |
Detailed Description
WORK IN PROGRESS, potential configurable behavior.
A ZGY file cannot be updated once created, but individual bricks might
be written to more than once while the file is still open for create.
Updating a brick might cause loss of quality if the update was made
as part of a read/modify/write cycle. It might also cause space to be
wasted in the file since ZGY does not try to recycle freed bricks.
For this reason the application should explicitly indicate that it
accepts the loss of quality and/or leakage.
Kinds of leakage:
- Brick to be overwritten is in a closed segment. This is
expected to be rare, and only relevant for cloud storage.
- Brick to be overwritten and/or new brick is compressed
and the new data is smaller. Leaks the size difference,
although for implementation reasons we might want to leak
the entire old brick ("Pedantic" mode).
- Brick to be overwritten and/or new brick is compressed
and the new data is larger. Leaks the old brick.
The default is "Always" for uncompressed local files and "Constant"
otherwise.
It is fairly safe to set an uncompressed cloud file to "Always" but
there are some scenarios where very small regions are written to a
large file where this might cause much leakage. So the caller
needs to confirm he knows what he is doing.
Compressed files should only be set to "Always" in very special cases
or in unit tests. The potential leakage is much larger, as is the
problem of multiple compress and decompress cycles causing noise.
The documentation for this class was generated from the following file:
- openzgy/impl/enum.py
