mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-22 04:33:22 +02:00
453 lines
12 KiB
C
453 lines
12 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* xlogutils.c
|
|
*
|
|
* PostgreSQL transaction log manager utility routines
|
|
*
|
|
* This file contains support routines that are used by XLOG replay functions.
|
|
* None of this code is used during normal system operation.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/backend/access/transam/xlogutils.c
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#include "postgres.h"
|
|
|
|
#include "access/xlog.h"
|
|
#include "access/xlogutils.h"
|
|
#include "catalog/catalog.h"
|
|
#include "storage/bufmgr.h"
|
|
#include "storage/smgr.h"
|
|
#include "utils/guc.h"
|
|
#include "utils/hsearch.h"
|
|
#include "utils/rel.h"
|
|
|
|
|
|
/*
|
|
* During XLOG replay, we may see XLOG records for incremental updates of
|
|
* pages that no longer exist, because their relation was later dropped or
|
|
* truncated. (Note: this is only possible when full_page_writes = OFF,
|
|
* since when it's ON, the first reference we see to a page should always
|
|
* be a full-page rewrite not an incremental update.) Rather than simply
|
|
* ignoring such records, we make a note of the referenced page, and then
|
|
* complain if we don't actually see a drop or truncate covering the page
|
|
* later in replay.
|
|
*/
|
|
typedef struct xl_invalid_page_key
|
|
{
|
|
RelFileNode node; /* the relation */
|
|
ForkNumber forkno; /* the fork number */
|
|
BlockNumber blkno; /* the page */
|
|
} xl_invalid_page_key;
|
|
|
|
typedef struct xl_invalid_page
|
|
{
|
|
xl_invalid_page_key key; /* hash key ... must be first */
|
|
bool present; /* page existed but contained zeroes */
|
|
} xl_invalid_page;
|
|
|
|
static HTAB *invalid_page_tab = NULL;
|
|
|
|
|
|
/* Log a reference to an invalid page */
|
|
static void
|
|
log_invalid_page(RelFileNode node, ForkNumber forkno, BlockNumber blkno,
|
|
bool present)
|
|
{
|
|
xl_invalid_page_key key;
|
|
xl_invalid_page *hentry;
|
|
bool found;
|
|
|
|
/*
|
|
* Log references to invalid pages at DEBUG1 level. This allows some
|
|
* tracing of the cause (note the elog context mechanism will tell us
|
|
* something about the XLOG record that generated the reference).
|
|
*/
|
|
if (log_min_messages <= DEBUG1 || client_min_messages <= DEBUG1)
|
|
{
|
|
char *path = relpathperm(node, forkno);
|
|
|
|
if (present)
|
|
elog(DEBUG1, "page %u of relation %s is uninitialized",
|
|
blkno, path);
|
|
else
|
|
elog(DEBUG1, "page %u of relation %s does not exist",
|
|
blkno, path);
|
|
pfree(path);
|
|
}
|
|
|
|
if (invalid_page_tab == NULL)
|
|
{
|
|
/* create hash table when first needed */
|
|
HASHCTL ctl;
|
|
|
|
memset(&ctl, 0, sizeof(ctl));
|
|
ctl.keysize = sizeof(xl_invalid_page_key);
|
|
ctl.entrysize = sizeof(xl_invalid_page);
|
|
ctl.hash = tag_hash;
|
|
|
|
invalid_page_tab = hash_create("XLOG invalid-page table",
|
|
100,
|
|
&ctl,
|
|
HASH_ELEM | HASH_FUNCTION);
|
|
}
|
|
|
|
/* we currently assume xl_invalid_page_key contains no padding */
|
|
key.node = node;
|
|
key.forkno = forkno;
|
|
key.blkno = blkno;
|
|
hentry = (xl_invalid_page *)
|
|
hash_search(invalid_page_tab, (void *) &key, HASH_ENTER, &found);
|
|
|
|
if (!found)
|
|
{
|
|
/* hash_search already filled in the key */
|
|
hentry->present = present;
|
|
}
|
|
else
|
|
{
|
|
/* repeat reference ... leave "present" as it was */
|
|
}
|
|
}
|
|
|
|
/* Forget any invalid pages >= minblkno, because they've been dropped */
|
|
static void
|
|
forget_invalid_pages(RelFileNode node, ForkNumber forkno, BlockNumber minblkno)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
xl_invalid_page *hentry;
|
|
|
|
if (invalid_page_tab == NULL)
|
|
return; /* nothing to do */
|
|
|
|
hash_seq_init(&status, invalid_page_tab);
|
|
|
|
while ((hentry = (xl_invalid_page *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
if (RelFileNodeEquals(hentry->key.node, node) &&
|
|
hentry->key.forkno == forkno &&
|
|
hentry->key.blkno >= minblkno)
|
|
{
|
|
if (log_min_messages <= DEBUG2 || client_min_messages <= DEBUG2)
|
|
{
|
|
char *path = relpathperm(hentry->key.node, forkno);
|
|
|
|
elog(DEBUG2, "page %u of relation %s has been dropped",
|
|
hentry->key.blkno, path);
|
|
pfree(path);
|
|
}
|
|
|
|
if (hash_search(invalid_page_tab,
|
|
(void *) &hentry->key,
|
|
HASH_REMOVE, NULL) == NULL)
|
|
elog(ERROR, "hash table corrupted");
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Forget any invalid pages in a whole database */
|
|
static void
|
|
forget_invalid_pages_db(Oid dbid)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
xl_invalid_page *hentry;
|
|
|
|
if (invalid_page_tab == NULL)
|
|
return; /* nothing to do */
|
|
|
|
hash_seq_init(&status, invalid_page_tab);
|
|
|
|
while ((hentry = (xl_invalid_page *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
if (hentry->key.node.dbNode == dbid)
|
|
{
|
|
if (log_min_messages <= DEBUG2 || client_min_messages <= DEBUG2)
|
|
{
|
|
char *path = relpathperm(hentry->key.node, hentry->key.forkno);
|
|
|
|
elog(DEBUG2, "page %u of relation %s has been dropped",
|
|
hentry->key.blkno, path);
|
|
pfree(path);
|
|
}
|
|
|
|
if (hash_search(invalid_page_tab,
|
|
(void *) &hentry->key,
|
|
HASH_REMOVE, NULL) == NULL)
|
|
elog(ERROR, "hash table corrupted");
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Complain about any remaining invalid-page entries */
|
|
void
|
|
XLogCheckInvalidPages(void)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
xl_invalid_page *hentry;
|
|
bool foundone = false;
|
|
|
|
if (invalid_page_tab == NULL)
|
|
return; /* nothing to do */
|
|
|
|
hash_seq_init(&status, invalid_page_tab);
|
|
|
|
/*
|
|
* Our strategy is to emit WARNING messages for all remaining entries and
|
|
* only PANIC after we've dumped all the available info.
|
|
*/
|
|
while ((hentry = (xl_invalid_page *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
char *path = relpathperm(hentry->key.node, hentry->key.forkno);
|
|
|
|
if (hentry->present)
|
|
elog(WARNING, "page %u of relation %s was uninitialized",
|
|
hentry->key.blkno, path);
|
|
else
|
|
elog(WARNING, "page %u of relation %s did not exist",
|
|
hentry->key.blkno, path);
|
|
pfree(path);
|
|
foundone = true;
|
|
}
|
|
|
|
if (foundone)
|
|
elog(PANIC, "WAL contains references to invalid pages");
|
|
|
|
hash_destroy(invalid_page_tab);
|
|
invalid_page_tab = NULL;
|
|
}
|
|
|
|
/*
|
|
* XLogReadBuffer
|
|
* Read a page during XLOG replay.
|
|
*
|
|
* This is a shorthand of XLogReadBufferExtended() followed by
|
|
* LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE), for reading from the main
|
|
* fork.
|
|
*
|
|
* (Getting the buffer lock is not really necessary during single-process
|
|
* crash recovery, but some subroutines such as MarkBufferDirty will complain
|
|
* if we don't have the lock. In hot standby mode it's definitely necessary.)
|
|
*
|
|
* The returned buffer is exclusively-locked.
|
|
*
|
|
* For historical reasons, instead of a ReadBufferMode argument, this only
|
|
* supports RBM_ZERO (init == true) and RBM_NORMAL (init == false) modes.
|
|
*/
|
|
Buffer
|
|
XLogReadBuffer(RelFileNode rnode, BlockNumber blkno, bool init)
|
|
{
|
|
Buffer buf;
|
|
|
|
buf = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno,
|
|
init ? RBM_ZERO : RBM_NORMAL);
|
|
if (BufferIsValid(buf))
|
|
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
|
|
|
|
return buf;
|
|
}
|
|
|
|
/*
|
|
* XLogReadBufferExtended
|
|
* Read a page during XLOG replay
|
|
*
|
|
* This is functionally comparable to ReadBufferExtended. There's some
|
|
* differences in the behavior wrt. the "mode" argument:
|
|
*
|
|
* In RBM_NORMAL mode, if the page doesn't exist, or contains all-zeroes, we
|
|
* return InvalidBuffer. In this case the caller should silently skip the
|
|
* update on this page. (In this situation, we expect that the page was later
|
|
* dropped or truncated. If we don't see evidence of that later in the WAL
|
|
* sequence, we'll complain at the end of WAL replay.)
|
|
*
|
|
* In RBM_ZERO and RBM_ZERO_ON_ERROR modes, if the page doesn't exist, the
|
|
* relation is extended with all-zeroes pages up to the given block number.
|
|
*/
|
|
Buffer
|
|
XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
|
|
BlockNumber blkno, ReadBufferMode mode)
|
|
{
|
|
BlockNumber lastblock;
|
|
Buffer buffer;
|
|
SMgrRelation smgr;
|
|
|
|
Assert(blkno != P_NEW);
|
|
|
|
/* Open the relation at smgr level */
|
|
smgr = smgropen(rnode, InvalidBackendId);
|
|
|
|
/*
|
|
* Create the target file if it doesn't already exist. This lets us cope
|
|
* if the replay sequence contains writes to a relation that is later
|
|
* deleted. (The original coding of this routine would instead suppress
|
|
* the writes, but that seems like it risks losing valuable data if the
|
|
* filesystem loses an inode during a crash. Better to write the data
|
|
* until we are actually told to delete the file.)
|
|
*/
|
|
smgrcreate(smgr, forknum, true);
|
|
|
|
lastblock = smgrnblocks(smgr, forknum);
|
|
|
|
if (blkno < lastblock)
|
|
{
|
|
/* page exists in file */
|
|
buffer = ReadBufferWithoutRelcache(rnode, forknum, blkno,
|
|
mode, NULL);
|
|
}
|
|
else
|
|
{
|
|
/* hm, page doesn't exist in file */
|
|
if (mode == RBM_NORMAL)
|
|
{
|
|
log_invalid_page(rnode, forknum, blkno, false);
|
|
return InvalidBuffer;
|
|
}
|
|
/* OK to extend the file */
|
|
/* we do this in recovery only - no rel-extension lock needed */
|
|
Assert(InRecovery);
|
|
buffer = InvalidBuffer;
|
|
while (blkno >= lastblock)
|
|
{
|
|
if (buffer != InvalidBuffer)
|
|
ReleaseBuffer(buffer);
|
|
buffer = ReadBufferWithoutRelcache(rnode, forknum,
|
|
P_NEW, mode, NULL);
|
|
lastblock++;
|
|
}
|
|
Assert(BufferGetBlockNumber(buffer) == blkno);
|
|
}
|
|
|
|
if (mode == RBM_NORMAL)
|
|
{
|
|
/* check that page has been initialized */
|
|
Page page = (Page) BufferGetPage(buffer);
|
|
|
|
/*
|
|
* We assume that PageIsNew is safe without a lock. During recovery,
|
|
* there should be no other backends that could modify the buffer at
|
|
* the same time.
|
|
*/
|
|
if (PageIsNew(page))
|
|
{
|
|
ReleaseBuffer(buffer);
|
|
log_invalid_page(rnode, forknum, blkno, true);
|
|
return InvalidBuffer;
|
|
}
|
|
}
|
|
|
|
return buffer;
|
|
}
|
|
|
|
|
|
/*
|
|
* Struct actually returned by XLogFakeRelcacheEntry, though the declared
|
|
* return type is Relation.
|
|
*/
|
|
typedef struct
|
|
{
|
|
RelationData reldata; /* Note: this must be first */
|
|
FormData_pg_class pgc;
|
|
} FakeRelCacheEntryData;
|
|
|
|
typedef FakeRelCacheEntryData *FakeRelCacheEntry;
|
|
|
|
/*
|
|
* Create a fake relation cache entry for a physical relation
|
|
*
|
|
* It's often convenient to use the same functions in XLOG replay as in the
|
|
* main codepath, but those functions typically work with a relcache entry.
|
|
* We don't have a working relation cache during XLOG replay, but this
|
|
* function can be used to create a fake relcache entry instead. Only the
|
|
* fields related to physical storage, like rd_rel, are initialized, so the
|
|
* fake entry is only usable in low-level operations like ReadBuffer().
|
|
*
|
|
* Caller must free the returned entry with FreeFakeRelcacheEntry().
|
|
*/
|
|
Relation
|
|
CreateFakeRelcacheEntry(RelFileNode rnode)
|
|
{
|
|
FakeRelCacheEntry fakeentry;
|
|
Relation rel;
|
|
|
|
/* Allocate the Relation struct and all related space in one block. */
|
|
fakeentry = palloc0(sizeof(FakeRelCacheEntryData));
|
|
rel = (Relation) fakeentry;
|
|
|
|
rel->rd_rel = &fakeentry->pgc;
|
|
rel->rd_node = rnode;
|
|
/* We will never be working with temp rels during recovery */
|
|
rel->rd_backend = InvalidBackendId;
|
|
|
|
/* We don't know the name of the relation; use relfilenode instead */
|
|
sprintf(RelationGetRelationName(rel), "%u", rnode.relNode);
|
|
|
|
/*
|
|
* We set up the lockRelId in case anything tries to lock the dummy
|
|
* relation. Note that this is fairly bogus since relNode may be
|
|
* different from the relation's OID. It shouldn't really matter though,
|
|
* since we are presumably running by ourselves and can't have any lock
|
|
* conflicts ...
|
|
*/
|
|
rel->rd_lockInfo.lockRelId.dbId = rnode.dbNode;
|
|
rel->rd_lockInfo.lockRelId.relId = rnode.relNode;
|
|
|
|
rel->rd_smgr = NULL;
|
|
|
|
return rel;
|
|
}
|
|
|
|
/*
|
|
* Free a fake relation cache entry.
|
|
*/
|
|
void
|
|
FreeFakeRelcacheEntry(Relation fakerel)
|
|
{
|
|
pfree(fakerel);
|
|
}
|
|
|
|
/*
|
|
* Drop a relation during XLOG replay
|
|
*
|
|
* This is called when the relation is about to be deleted; we need to remove
|
|
* any open "invalid-page" records for the relation.
|
|
*/
|
|
void
|
|
XLogDropRelation(RelFileNode rnode, ForkNumber forknum)
|
|
{
|
|
forget_invalid_pages(rnode, forknum, 0);
|
|
}
|
|
|
|
/*
|
|
* Drop a whole database during XLOG replay
|
|
*
|
|
* As above, but for DROP DATABASE instead of dropping a single rel
|
|
*/
|
|
void
|
|
XLogDropDatabase(Oid dbid)
|
|
{
|
|
/*
|
|
* This is unnecessarily heavy-handed, as it will close SMgrRelation
|
|
* objects for other databases as well. DROP DATABASE occurs seldom enough
|
|
* that it's not worth introducing a variant of smgrclose for just this
|
|
* purpose. XXX: Or should we rather leave the smgr entries dangling?
|
|
*/
|
|
smgrcloseall();
|
|
|
|
forget_invalid_pages_db(dbid);
|
|
}
|
|
|
|
/*
|
|
* Truncate a relation during XLOG replay
|
|
*
|
|
* We need to clean up any open "invalid-page" records for the dropped pages.
|
|
*/
|
|
void
|
|
XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum,
|
|
BlockNumber nblocks)
|
|
{
|
|
forget_invalid_pages(rnode, forkNum, nblocks);
|
|
}
|