[pgpointcloud] Wrong serialized size of a PcPoint ?

[Paul Ramsey]

No, it won’t sum up, since the serialized points are’t what get packed into patches.  


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On April 8, 2015 at 2:56:10 AM, Sandro Santilli (strk at keybit.net) wrote:
> Checking the size of PcPoint values (with pc_memsize and pg_column_size)
> I found that we're using 11 bytes for the header when instead only 8 are
> required:
>  
> typedef struct
> {
> uint32_t size; // 4
> uint32_t pcid; // +4 = 8
> uint8_t data[1];
> }
> SERIALIZED_POINT;
>  
> This is because the code uses sizeof(SERIALIZED_POINT) - 1 to determine
> the required size, but sizeof(SERIALIZED_POINT) is 12 on my machine,
> rather than 9 as expected by the code.
>  
> In turn, 12 means that the structure is padded to the closest 4bytes
> boundary (4+4+4 rather than 4+4+1).
>  
> As we're going to add the actual size of the dimensions, that padding
> would not necessarely be needed. For example, a PcPoint with 3 4bytes
> dimensions would be perfectly aligned with just 16 bytes. Instead
> it uses 8+11=19 bytes.
>  
> Similar assumption (no padding) is done for the PcPatch case, whose
> struct also ends with an uint8_t.
>  
> I hadn't checked if such 3 bytes padding sums up for each point in
> a patch but it sounds like something worth inspecting.
>  
> --strk;
>  
> () Free GIS & Flash consultant/developer
> /\ http://strk.keybit.net/services.html
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