| From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
|---|---|
| To: | sunpeng <bluevaley(at)gmail(dot)com> |
| Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: hi, is it dangerous to only use tuple pointer through heap_getnext()? |
| Date: | 2010-05-15 01:15:34 |
| Message-ID: | 1273886083-sup-6446@alvh.no-ip.org |
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| Lists: | pgsql-general |
Excerpts from sunpeng's message of vie may 14 19:15:47 -0400 2010:
> hi,i use these codes to store only pointer of tuple :
> HeapTuple *tuple;
> tuple = heap_getnext(pHeapScanDesc,ForwardScanDirection);
> while(tuple){
> //[1#]here i only store the pointer of tuple in an array for later
> using,that means i don't retrive attribute data from this tuple ,is this ok?
No, this is not safe. The buffer is unpinned after heap_getnext walks
to the next buffer, and thus could be used for a different page.
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