* updated/deleted by the inserting transaction.
*
* Look for a committed hint bit, or if no xmin bit is set, check clog.
- * This needs to work on both primary and standby, where it is used to
- * assess btree delete records.
*/
if (HeapTupleHeaderXminCommitted(tuple) ||
(!HeapTupleHeaderXminInvalid(tuple) && TransactionIdDidCommit(xmin)))
of optimising for performance. When a hint is written we use
MarkBufferDirtyHint() to mark the block dirty.
-If the buffer is clean and checksums are in use then
-MarkBufferDirtyHint() inserts an XLOG_FPI record to ensure that we
-take a full page image that includes the hint. We do this to avoid
-a partial page write, when we write the dirtied page. WAL is not
-written during recovery, so we simply skip dirtying blocks because
-of hints when in recovery.
+If the buffer is clean and checksums are in use then MarkBufferDirtyHint()
+inserts an XLOG_FPI_FOR_HINT record to ensure that we take a full page image
+that includes the hint. We do this to avoid a partial page write, when we
+write the dirtied page. WAL is not written during recovery, so we simply skip
+dirtying blocks because of hints when in recovery.
If you do decide to optimise away a WAL record, then any calls to
MarkBufferDirty() must be replaced by MarkBufferDirtyHint(),
* We'll refuse to continue assigning XIDs in interactive mode once we get
* within 3M transactions of data loss. This leaves lots of room for the
* DBA to fool around fixing things in a standalone backend, while not
- * being significant compared to total XID space. (Note that since
- * vacuuming requires one transaction per table cleaned, we had better be
- * sure there's lots of XIDs left...) Also, at default BLCKSZ, this
- * leaves two completely-idle segments. In the event of edge-case bugs
- * involving page or segment arithmetic, idle segments render the bugs
- * unreachable outside of single-user mode.
+ * being significant compared to total XID space. (VACUUM requires an XID
+ * if it truncates at wal_level!=minimal. "VACUUM (ANALYZE)", which a DBA
+ * might do by reflex, assigns an XID. Hence, we had better be sure
+ * there's lots of XIDs left...) Also, at default BLCKSZ, this leaves two
+ * completely-idle segments. In the event of edge-case bugs involving
+ * page or segment arithmetic, idle segments render the bugs unreachable
+ * outside of single-user mode.
*/
xidStopLimit = xidWrapLimit - 3000000;
if (xidStopLimit < FirstNormalTransactionId)
#define QUEUE_FULL_WARN_INTERVAL 5000 /* warn at most once every 5s */
/*
- * slru.c currently assumes that all filenames are four characters of hex
- * digits. That means that we can use segments 0000 through FFFF.
- * Each segment contains SLRU_PAGES_PER_SEGMENT pages which gives us
- * the pages from 0 to SLRU_PAGES_PER_SEGMENT * 0x10000 - 1.
- *
- * It's of course possible to enhance slru.c, but this gives us so much
- * space already that it doesn't seem worth the trouble.
+ * Use segments 0000 through FFFF. Each contains SLRU_PAGES_PER_SEGMENT pages
+ * which gives us the pages from 0 to SLRU_PAGES_PER_SEGMENT * 0x10000 - 1.
+ * We could use as many segments as SlruScanDirectory() allows, but this gives
+ * us so much space already that it doesn't seem worth the trouble.
*
* The most data we can have in the queue at a time is QUEUE_MAX_PAGE/2
* pages, because more than that would confuse slru.c into thinking there
/*
* We can always ignore processes running lazy vacuum. This is because we
* use these values only for deciding which tuples we must keep in the
- * tables. Since lazy vacuum doesn't write its XID anywhere, it's safe to
- * ignore it. In theory it could be problematic to ignore lazy vacuums in
- * a full vacuum, but keep in mind that only one vacuum process can be
- * working on a particular table at any time, and that each vacuum is
- * always an independent transaction.
+ * tables. Since lazy vacuum doesn't write its XID anywhere (usually no
+ * XID assigned), it's safe to ignore it. In theory it could be
+ * problematic to ignore lazy vacuums in a full vacuum, but keep in mind
+ * that only one vacuum process can be working on a particular table at
+ * any time, and that each vacuum is always an independent transaction.
*/
*oldestXmin = GetOldestNonRemovableTransactionId(rel);
* This is essentially the same as MarkBufferDirty, except:
*
* 1. The caller does not write WAL; so if checksums are enabled, we may need
- * to write an XLOG_FPI WAL record to protect against torn pages.
+ * to write an XLOG_FPI_FOR_HINT WAL record to protect against torn pages.
* 2. The caller might have only share-lock instead of exclusive-lock on the
* buffer's content lock.
* 3. This function does not guarantee that the buffer is always marked dirty
double rec_len_pct,
fpi_len_pct;
- /* ---
- * Make a first pass to calculate column totals:
- * count(*),
- * sum(xl_len+SizeOfXLogRecord),
- * sum(xl_tot_len-xl_len-SizeOfXLogRecord), and
- * sum(xl_tot_len).
- * These are used to calculate percentages for each record type.
- * ---
+ /*
+ * Each row shows its percentages of the total, so make a first pass to
+ * calculate column totals.
*/
for (ri = 0; ri < RM_NEXT_ID; ri++)
/*
* When there is not enough space on current page for whole record, we
* continue on the next page. xlp_rem_len is the number of bytes
- * remaining from a previous page.
- *
- * Note that xlp_rem_len includes backup-block data; that is, it tracks
- * xl_tot_len not xl_len in the initial header. Also note that the
- * continuation data isn't necessarily aligned.
+ * remaining from a previous page; it tracks xl_tot_len in the initial
+ * header. Note that the continuation data isn't necessarily aligned.
*/
uint32 xlp_rem_len; /* total len of remaining data for record */
} XLogPageHeaderData;
including server and client tools, and is therefore kept separate and
not run by default.
-Also, this test suite creates a KDC server that listens for TCP/IP
-connections on localhost without any real access control, so it is not
-safe to run this on a system where there might be untrusted local
-users.
+CAUTION: The test server run by this test is configured to listen for TCP
+connections on localhost. Any user on the same host is able to log in to the
+test server while the tests are running. Do not run this suite on a multi-user
+system where you don't trust all local users! Also, this test suite creates a
+KDC server that listens for TCP/IP connections on localhost without any real
+access control.
Running the tests
=================
return $ret;
}
-# Automatically shut down any still-running nodes when the test script exits.
-# Note that this just stops the postmasters (in the same order the nodes were
-# created in). Any temporary directories are deleted, in an unspecified
-# order, later when the File::Temp objects are destroyed.
+# Automatically shut down any still-running nodes (in the same order the nodes
+# were created in) when the test script exits.
END
{
# Examine the physical slot the replica uses to stream changes
# from the primary to make sure its hot_standby_feedback
# has locked in a catalog_xmin on the physical slot, and that
-# any xmin is < the catalog_xmin
+# any xmin is >= the catalog_xmin
$node_primary->poll_query_until(
'postgres', q[
SELECT catalog_xmin IS NOT NULL
# - a database called trustdb that lets anyone in
# - another database called certdb that uses certificate authentication, ie.
# the client must present a valid certificate signed by the client CA
-# - two users, called ssltestuser and anotheruser.
#
# The server is configured to only accept connections from localhost. If you
# want to run the client from another host, you'll have to configure that
projects / postgresql.git / commitdiff