appending variables in save causing file corruption

Question

Oliver Warlow 2019-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/478125-appending-variables-in-save-causing-file-corruption

评论： Oliver Warlow 2021-4-18

Hi,

I have some .mat files containing several variables of type 'Table'. I perform some analysis and replace some of these variables using the command

save('FileName', {'VarX', 'VarY', etc}, 'mat', '-append')

In this case there are other variables in the file appart from VarX and VarY which I am not overwriting. this seems to work most of the time, but every now and again i get an error:

Error using save

Error closing file 'FileName'

The file may be corrupt.

The files I am dealing with are around 250-500MB in size.

Any ideas why this might happen? It means I then corrupt my original data which is annoying. Perhaps I am best to create a totally new file with the new data and then replace the old file, therefore if I do get a corrupt file when writing I won't have destroyed my original data.

Thanks

Oli.

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Robert Reid 2021-4-17

编辑：Robert Reid 2021-4-17

Hi Oli,

I think that I am running into the exact same problem - your description at least matches my issue exactly.

Did you ever find a good solution to this?

Just saw Sai's answer below - did matfile help solve this issue?

Thanks,

Rob

Oliver Warlow 2021-4-18

Hi Rob,

I have to say I think i just implemented a rather memory wastful method of loading the complete file and resaving rather than appending the new data. I think that the problem was actually related to the files being located on a local network drive rather than local on my machine, I found this was causing corruption issues, to get round this agains I implemented not a very efficienct work around which was to save the file locally and then copy it to its required location. I never actually tried using the matfile method as I think I had already implemented my work around.

sorry for not being much more help. I have now changed the way I manage this data storing it as tales on an SQL server instead of as .mat files

O.

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Answer 1

Sai Bhargav Avula 2019-11-6

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https://ww2.mathworks.cn/matlabcentral/answers/478125-appending-variables-in-save-causing-file-corruption#answer_400106

编辑：Sai Bhargav Avula 2019-11-6

Hi,

One reason that the files get corrupted is because you might be trying to overwrite it before it could save the old process.

Also I would recommend you to use the matfile, as it can access and change the variables without loading it into the memory. Because of this the MAT file object requires less memory than the load and save commands.

Hope this helps!