Re: [REVIEW] Re: Compression of full-page-writes

>>>Do we release the buffers for compressed data when fpw is changed from
"compress" to "on"? 
>> The current code does not do this.
>Don't we need to do that? 
Yes this needs to be done in order to avoid memory leak when compression is
turned off at runtime while the backend session is running.

>You don't need to make the processes except the startup process allocate 
>the memory for uncompressedPages when fpw=on. Only the startup process 
>uses it for the WAL decompression
I see. fpw != on check can be put at the time of memory allocation of
uncompressedPages in the backend code . And at the time of recovery
uncompressedPages can be allocated separately if not already allocated.

>BTW, what happens if the memory allocation for uncompressedPages for 
>the recovery fails? 
The current code does not handle this. This will be rectified.

>Which would prevent the recovery at all, so PANIC should 
>happen in that case? 
IIUC, instead of reporting  PANIC , palloc can be used to allocate memory
for uncompressedPages at the time of recovery which will throw ERROR and
abort startup process in case of failure.


Thank you,
Rahila Syed



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