>>> > I think this will work, but not sure if there is a merit to deviate
>>> > from what btree does to handle this case. One thing I find slightly
>>> > awkward in hash_xlog_vacuum_get_latestRemovedXid() is that you are
>>> > using a number of tuples registered as part of fixed data
>>> > (xl_hash_vacuum_one_page) to traverse the data registered as buf data.
>>> > I think it will be better if we register offsets also in fixed part of
>>> > data as we are doing btree case.
>>
>> Agreed. I have made the changes accordingly. Please check attached v2 patch.
>>
>
> Changes look good to me. I think you can modify the comments in
> structure xl_hash_vacuum_one_page to mention "TARGET OFFSET NUMBERS
> FOLLOW AT THE END"
>
Added the comment in xl_hash_vacuum_one_page structure.
>>>
>>> >
>>> >
>>>
>>> Also another small point in this regard, do we need two separate
>>> variables to track number of deleted items in below code? I think one
>>> variable is sufficient.
>>>
>>> _hash_vacuum_one_page()
>>> {
>>> ..
>>> deletable[ndeletable++] = offnum;
>>> tuples_removed += 1;--
>>>
>>
>> Yes, I think 'ndeletable' alone should be fine.
>>
>
> I think it would have been probably okay to use *int* for ntuples as
> that matches with what you are actually assigning in the function.
okay, corrected it. Attached is newer version of patch.
--
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com
diff --git a/src/backend/access/hash/hash_xlog.c b/src/backend/access/hash/hash_xlog.c
index da4c2c5..2ccaf46 100644
--- a/src/backend/access/hash/hash_xlog.c
+++ b/src/backend/access/hash/hash_xlog.c
@@ -966,8 +966,6 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record)
OffsetNumber hoffnum;
TransactionId latestRemovedXid = InvalidTransactionId;
int i;
- char *ptr;
- Size len;
xlrec = (xl_hash_vacuum_one_page *) XLogRecGetData(record);
@@ -986,12 +984,20 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record)
return latestRemovedXid;
/*
+ * Check if WAL replay has reached a consistent database state. If not,
+ * we must PANIC. See the definition of btree_xlog_delete_get_latestRemovedXid
+ * for more details.
+ */
+ if (!reachedConsistency)
+ elog(PANIC, "hash_xlog_vacuum_get_latestRemovedXid: cannot operate with inconsistent data");
+
+ /*
* Get index page. If the DB is consistent, this should not fail, nor
* should any of the heap page fetches below. If one does, we return
* InvalidTransactionId to cancel all HS transactions. That's probably
* overkill, but it's safe, and certainly better than panicking here.
*/
- XLogRecGetBlockTag(record, 1, &rnode, NULL, &blkno);
+ XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno);
ibuffer = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno, RBM_NORMAL);
if (!BufferIsValid(ibuffer))
@@ -1003,9 +1009,7 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record)
* Loop through the deleted index items to obtain the TransactionId from
* the heap items they point to.
*/
- ptr = XLogRecGetBlockData(record, 1, &len);
-
- unused = (OffsetNumber *) ptr;
+ unused = (OffsetNumber *) ((char *) xlrec + SizeOfHashVacuumOnePage);
for (i = 0; i < xlrec->ntuples; i++)
{
@@ -1130,23 +1134,15 @@ hash_xlog_vacuum_one_page(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
- char *ptr;
- Size len;
-
- ptr = XLogRecGetBlockData(record, 0, &len);
-
page = (Page) BufferGetPage(buffer);
- if (len > 0)
+ if (XLogRecGetDataLen(record) > SizeOfHashVacuumOnePage)
{
OffsetNumber *unused;
- OffsetNumber *unend;
- unused = (OffsetNumber *) ptr;
- unend = (OffsetNumber *) ((char *) ptr + len);
+ unused = (OffsetNumber *) ((char *) xldata + SizeOfHashVacuumOnePage);
- if ((unend - unused) > 0)
- PageIndexMultiDelete(page, unused, unend - unused);
+ PageIndexMultiDelete(page, unused, xldata->ntuples);
}
/*
diff --git a/src/backend/access/hash/hashinsert.c b/src/backend/access/hash/hashinsert.c
index 8640e85..8699b5b 100644
--- a/src/backend/access/hash/hashinsert.c
+++ b/src/backend/access/hash/hashinsert.c
@@ -344,7 +344,6 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf,
Page page = BufferGetPage(buf);
HashPageOpaque pageopaque;
HashMetaPage metap;
- double tuples_removed = 0;
/* Scan each tuple in page to see if it is marked as LP_DEAD */
maxoff = PageGetMaxOffsetNumber(page);
@@ -355,10 +354,7 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf,
ItemId itemId = PageGetItemId(page, offnum);
if (ItemIdIsDead(itemId))
- {
deletable[ndeletable++] = offnum;
- tuples_removed += 1;
- }
}
if (ndeletable > 0)
@@ -386,7 +382,7 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf,
pageopaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES;
metap = HashPageGetMeta(BufferGetPage(metabuf));
- metap->hashm_ntuples -= tuples_removed;
+ metap->hashm_ntuples -= ndeletable;
MarkBufferDirty(buf);
MarkBufferDirty(metabuf);
@@ -398,13 +394,18 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf,
XLogRecPtr recptr;
xlrec.hnode = hnode;
- xlrec.ntuples = tuples_removed;
+ xlrec.ntuples = ndeletable;
XLogBeginInsert();
+ XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
XLogRegisterData((char *) &xlrec, SizeOfHashVacuumOnePage);
- XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) deletable,
+ /*
+ * We need the target-offsets array whether or not we store the whole
+ * buffer, to allow us to find the latestRemovedXid on a standby
+ * server.
+ */
+ XLogRegisterData((char *) deletable,
ndeletable * sizeof(OffsetNumber));
XLogRegisterBuffer(1, metabuf, REGBUF_STANDARD);
diff --git a/src/backend/access/rmgrdesc/hashdesc.c b/src/backend/access/rmgrdesc/hashdesc.c
index 5f5f4a0..35d86dc 100644
--- a/src/backend/access/rmgrdesc/hashdesc.c
+++ b/src/backend/access/rmgrdesc/hashdesc.c
@@ -113,7 +113,7 @@ hash_desc(StringInfo buf, XLogReaderState *record)
{
xl_hash_vacuum_one_page *xlrec = (xl_hash_vacuum_one_page *) rec;
- appendStringInfo(buf, "ntuples %g",
+ appendStringInfo(buf, "ntuples %d",
xlrec->ntuples);
break;
}
diff --git a/src/include/access/hash_xlog.h b/src/include/access/hash_xlog.h
index 2e64cfa..644da2e 100644
--- a/src/include/access/hash_xlog.h
+++ b/src/include/access/hash_xlog.h
@@ -265,11 +265,13 @@ typedef struct xl_hash_init_bitmap_page
typedef struct xl_hash_vacuum_one_page
{
RelFileNode hnode;
- double ntuples;
+ int ntuples;
+
+ /* TARGET OFFSET NUMBERS FOLLOW AT THE END */
} xl_hash_vacuum_one_page;
#define SizeOfHashVacuumOnePage \
- (offsetof(xl_hash_vacuum_one_page, ntuples) + sizeof(double))
+ (offsetof(xl_hash_vacuum_one_page, ntuples) + sizeof(int))
extern void hash_redo(XLogReaderState *record);
extern void hash_desc(StringInfo buf, XLogReaderState *record);
--
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