PyTables parameter files¶
PyTables issues warnings when certain limits are exceeded. Those limits are not intrinsic limitations of the underlying software, but rather are proactive measures to avoid large resource consumptions. The default limits should be enough for most of cases, and users should try to respect them. However, in some situations, it can be convenient to increase (or decrease) these limits.
Also, and in order to get maximum performance, PyTables implements a series of sophisticated features, like I/O buffers or different kind of caches (for nodes, chunks and other internal metadata). These features comes with a default set of parameters that ensures a decent performance in most of situations. But, as there is always a need for every case, it is handy to have the possibility to fine-tune some of these parameters.
Because of these reasons, PyTables implements a couple of ways to change the
values of these parameters. All the tunable parameters live in the
tables/parameters.py. The user can choose to change them in the
parameter files themselves for a global and persistent change. Moreover, if
he wants a finer control, he can pass any of these parameters directly to the
tables.open_file() function, and the new parameters will only take
effect in the corresponding file (the defaults will continue to be in the
parameter files).
A description of all of the tunable parameters follows. As the defaults stated here may change from release to release, please check with your actual parameter files so as to know your actual default values.
Warning
Changing the next parameters may have a very bad effect in the resource consumption and performance of your PyTables scripts.
Please be careful when touching these!
Tunable parameters in parameters.py¶
Recommended maximum values¶
Cache limits¶
Parameters for the different internal caches¶
Parameters for general cache behaviour¶
Warning
The next parameters will not take any effect if passed to the open_file() function, so they can only be changed in a global way. You can change them in the file, but this is strongly discouraged unless you know well what you are doing.
