Fixes for single-page hash index vacuum.

robertmhaas · robertmhaas · commit 953477ca3526 · 2017-03-20T15:49:09.000-04:00
Clear LH_PAGE_HAS_DEAD_TUPLES during replay, similar to what gets done for btree. Update hashdesc.c for xl_hash_vacuum_one_page. Oversights in commit 6977b8b spotted by Amit Kapila. Patch by Ashutosh Sharma. Bump WAL version. The original patch to make hash indexes write-ahead logged probably should have done this, and the single page vacuuming patch probably should have done it again, but better late than never. Discussion: http://postgr.es/m/CAA4eK1Kd=mJ9xreovcsh0qMiAj-QqCphHVQ_Lfau1DR9oVjASQ@mail.gmail.com
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
@@ -790,6 +790,7 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 		OffsetNumber deletable[MaxOffsetNumber];
 		int			ndeletable = 0;
 		bool		retain_pin = false;
+		bool		clear_dead_marking = false;
 
 		vacuum_delay_point();
 
@@ -877,11 +878,14 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 			/*
 			 * Let us mark the page as clean if vacuum removes the DEAD tuples
 			 * from an index page. We do this by clearing LH_PAGE_HAS_DEAD_TUPLES
-			 * flag. Clearing this flag is just a hint; replay won't redo this.
+			 * flag.
 			 */
 			if (tuples_removed && *tuples_removed > 0 &&
 				opaque->hasho_flag & LH_PAGE_HAS_DEAD_TUPLES)
+			{
 				opaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES;
+				clear_dead_marking = true;
+			}
 
 			MarkBufferDirty(buf);
 
@@ -891,6 +895,7 @@ hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf,
 				xl_hash_delete xlrec;
 				XLogRecPtr	recptr;
 
+				xlrec.clear_dead_marking = clear_dead_marking;
 				xlrec.is_primary_bucket_page = (buf == bucket_buf) ? true : false;
 
 				XLogBeginInsert();
diff --git a/src/backend/access/hash/hash_xlog.c b/src/backend/access/hash/hash_xlog.c
@@ -859,6 +859,19 @@ hash_xlog_delete(XLogReaderState *record)
 				PageIndexMultiDelete(page, unused, unend - unused);
 		}
 
+		/*
+		 * Mark the page as not containing any LP_DEAD items only if
+		 * clear_dead_marking flag is set to true. See comments in
+		 * hashbucketcleanup() for details.
+		 */
+		if (xldata->clear_dead_marking)
+		{
+			HashPageOpaque pageopaque;
+
+			pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
+			pageopaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES;
+		}
+
 		PageSetLSN(page, lsn);
 		MarkBufferDirty(deletebuf);
 	}
@@ -1078,6 +1091,7 @@ hash_xlog_vacuum_one_page(XLogReaderState *record)
 	Buffer metabuf;
 	Page page;
 	XLogRedoAction action;
+	HashPageOpaque pageopaque;
 
 	xldata = (xl_hash_vacuum_one_page *) XLogRecGetData(record);
 
@@ -1126,6 +1140,13 @@ hash_xlog_vacuum_one_page(XLogReaderState *record)
 				PageIndexMultiDelete(page, unused, unend - unused);
 		}
 
+		/*
+		 * Mark the page as not containing any LP_DEAD items. See comments
+		 * in _hash_vacuum_one_page() for details.
+		 */
+		pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
+		pageopaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES;
+
 		PageSetLSN(page, lsn);
 		MarkBufferDirty(buffer);
 	}
diff --git a/src/backend/access/hash/hashinsert.c b/src/backend/access/hash/hashinsert.c
@@ -374,6 +374,14 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf,
 
 		PageIndexMultiDelete(page, deletable, ndeletable);
 
+		/*
+		 * Mark the page as not containing any LP_DEAD items. This is not
+		 * certainly true (there might be some that have recently been marked,
+		 * but weren't included in our target-item list), but it will almost
+		 * always be true and it doesn't seem worth an additional page scan
+		 * to check it. Remember that LH_PAGE_HAS_DEAD_TUPLES is only a hint
+		 * anyway.
+		 */
 		pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
 		pageopaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES;
 
diff --git a/src/backend/access/rmgrdesc/hashdesc.c b/src/backend/access/rmgrdesc/hashdesc.c
@@ -96,14 +96,23 @@ hash_desc(StringInfo buf, XLogReaderState *record)
 			{
 				xl_hash_delete *xlrec = (xl_hash_delete *) rec;
 
-				appendStringInfo(buf, "is_primary %c",
+				appendStringInfo(buf, "clear_dead_marking %c, is_primary %c",
+								 xlrec->clear_dead_marking ? 'T' : 'F',
 								 xlrec->is_primary_bucket_page ? 'T' : 'F');
 				break;
 			}
 		case XLOG_HASH_UPDATE_META_PAGE:
 			{
 				xl_hash_update_meta_page *xlrec = (xl_hash_update_meta_page *) rec;
 
+				appendStringInfo(buf, "ntuples %g",
+								 xlrec->ntuples);
+				break;
+			}
+		case XLOG_HASH_VACUUM_ONE_PAGE:
+			{
+				xl_hash_vacuum_one_page *xlrec = (xl_hash_vacuum_one_page *) rec;
+
 				appendStringInfo(buf, "ntuples %g",
 								 xlrec->ntuples);
 				break;
diff --git a/src/include/access/hash_xlog.h b/src/include/access/hash_xlog.h
@@ -197,6 +197,8 @@ typedef struct xl_hash_squeeze_page
  */
 typedef struct xl_hash_delete
 {
+	bool		clear_dead_marking;		/* TRUE if this operation clears
+										 * LH_PAGE_HAS_DEAD_TUPLES flag */
 	bool		is_primary_bucket_page; /* TRUE if the operation is for
 										 * primary bucket page */
 }	xl_hash_delete;
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
@@ -31,7 +31,7 @@
 /*
  * Each page of XLOG file has a header like this:
  */
-#define XLOG_PAGE_MAGIC 0xD095	/* can be used as WAL version indicator */
+#define XLOG_PAGE_MAGIC 0xD096	/* can be used as WAL version indicator */
 
 typedef struct XLogPageHeaderData
 {

Original file line number	Diff line number	Diff line change
`@@ -197,6 +197,8 @@ typedef struct xl_hash_squeeze_page`
`197`	`197`	`*/`
`198`	`198`	`typedef struct xl_hash_delete`
`199`	`199`	`{`
	`200`	`+ bool clear_dead_marking; /* TRUE if this operation clears`
	`201`	`+ * LH_PAGE_HAS_DEAD_TUPLES flag */`
`200`	`202`	`bool is_primary_bucket_page; /* TRUE if the operation is for`
`201`	`203`	`* primary bucket page */`
`202`	`204`	`} xl_hash_delete;`
Original file line number	Diff line number	Diff line change
`@@ -31,7 +31,7 @@`
`31`	`31`	`/*`
`32`	`32`	`* Each page of XLOG file has a header like this:`
`33`	`33`	`*/`
`34`		`-#define XLOG_PAGE_MAGIC 0xD095 /* can be used as WAL version indicator */`
	`34`	`+#define XLOG_PAGE_MAGIC 0xD096 /* can be used as WAL version indicator */`
`35`	`35`
`36`	`36`	`typedef struct XLogPageHeaderData`
`37`	`37`	`{`