mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix ancient docs/comments thinko: XID comparison is mod 2^32, not 2^31.

Browse Source 
Pointed out by Gianni Ciolli.
This commit is contained in:
Tom Lane 2013-12-12 12:39:48 -05:00
parent f26099057a
commit ccca6f56f5
2 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
doc/src/sgml/maintenance.sgml
View File

@ -401,7 +401,7 @@
as <literal>FrozenXID</>. This XID does not follow the normal XID as <literal>FrozenXID</>. This XID does not follow the normal XID
comparison rules and is always considered older comparison rules and is always considered older
than every normal XID. Normal XIDs are than every normal XID. Normal XIDs are
compared using modulo-2<superscript>31</> arithmetic. This means compared using modulo-2<superscript>32</> arithmetic. This means
that for every normal XID, there are two billion XIDs that are that for every normal XID, there are two billion XIDs that are
<quote>older</> and two billion that are <quote>newer</>; another <quote>older</> and two billion that are <quote>newer</>; another
way to say it is that the normal XID space is circular with no way to say it is that the normal XID space is circular with no

2
src/backend/access/transam/transam.c
View File

@ -301,7 +301,7 @@ TransactionIdPrecedes(TransactionId id1, TransactionId id2)
{ {
/* /*
* If either ID is a permanent XID then we can just do unsigned * If either ID is a permanent XID then we can just do unsigned
* comparison. If both are normal, do a modulo-2^31 comparison. * comparison. If both are normal, do a modulo-2^32 comparison.
*/ */
int32 diff; int32 diff;