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Replace implementation of pg_log as a relation accessed through the

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buffer manager with 'pg_clog', a specialized access method modeled
on pg_xlog.  This simplifies startup (don't need to play games to
open pg_log; among other things, OverrideTransactionSystem goes away),
should improve performance a little, and opens the door to recycling
commit log space by removing no-longer-needed segments of the commit
log.  Actual recycling is not there yet, but I felt I should commit
this part separately since it'd still be useful if we chose not to
do transaction ID wraparound.
This commit is contained in:
Tom Lane
2001-08-25 18:52:43 +00:00
parent 4699d81dc9
commit 2589735da0
39 changed files with 1248 additions and 1128 deletions
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4
src/backend/storage/buffer/README
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@@ -1,4 +1,4 @@
$Header: /cvsroot/pgsql/src/backend/storage/buffer/README,v 1.1 2001/07/06 21:04:25 tgl Exp $
$Header: /cvsroot/pgsql/src/backend/storage/buffer/README,v 1.2 2001/08/25 18:52:42 tgl Exp $
Notes about shared buffer access rules
--------------------------------------
@@ -66,7 +66,7 @@ at about the same time would OR the same bits into the field, so there
is little or no risk of conflicting update; what's more, if there did
manage to be a conflict it would merely mean that one bit-update would
be lost and need to be done again later. These four bits are only hints
(they cache the results of transaction status lookups in pg_log), so no
(they cache the results of transaction status lookups in pg_clog), so no
great harm is done if they get reset to zero by conflicting updates.
5. To physically remove a tuple or compact free space on a page, one