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Add more detail why repalloc and pfree do not accept NULL pointers

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Per discussion, we choose not to change this.  This just gives a
little bit more information.

Discussion: https://www.postgresql.org/message-id/flat/cf26e970-8e92-59f1-247a-aa265235075b%40enterprisedb.com
This commit is contained in:
Peter Eisentraut 2022-08-28 09:55:04 +02:00
parent 36389a060c
commit 805a397db4
1 changed files with 6 additions and 0 deletions
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src/backend/utils/mmgr/README
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@ -67,6 +67,12 @@ chunk might later be repalloc'd larger; it can also be pfree'd without
error. Similarly, repalloc allows realloc'ing to zero size. error. Similarly, repalloc allows realloc'ing to zero size.
* pfree and repalloc do not accept a NULL pointer. This is intentional. * pfree and repalloc do not accept a NULL pointer. This is intentional.
(For repalloc, this is necessary: As mentioned above, repalloc does
not depend on the current memory context. But then it needs to know
which memory context to do the allocation in. So the first allocation
has to be done outside of repalloc. For pfree, this behavior is
mostly historical and partially because the extra check would impact
performance.)
The Current Memory Context The Current Memory Context