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Doc: update pg_list.h header comments to include XidLists.

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I realize that the XidList infrastructure is rather incomplete,
but failing to mention it in adjacent comments takes that a bit
too far.
This commit is contained in:
Tom Lane 2022-12-17 10:31:25 -05:00
parent 935277b241
commit 0efecb5518
1 changed files with 6 additions and 4 deletions
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10
src/include/nodes/pg_list.h
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@ -15,16 +15,18 @@
* Non-empty lists have a header, which will not be relocated as long as the
* list remains non-empty, and an expansible data array.
*
* We support three types of lists:
* We support four types of lists:
*
* T_List: lists of pointers
* (in practice usually pointers to Nodes, but not always;
* declared as "void *" to minimize casting annoyances)
* T_IntList: lists of integers
* T_OidList: lists of Oids
* T_XidList: lists of TransactionIds
* (the XidList infrastructure is less complete than the other cases)
*
* (At the moment, ints and Oids are the same size, but they may not
* always be so; try to be careful to maintain the distinction.)
* (At the moment, ints, Oids, and XIDs are the same size, but they may not
* always be so; be careful to use the appropriate list type for your data.)
*
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
@ -50,7 +52,7 @@ typedef union ListCell
typedef struct List
{
NodeTag type; /* T_List, T_IntList, or T_OidList */
NodeTag type; /* T_List, T_IntList, T_OidList, or T_XidList */
int length; /* number of elements currently present */
int max_length; /* allocated length of elements[] */
ListCell *elements; /* re-allocatable array of cells */