hash: Add write-ahead logging support.

The warning about hash indexes not being write-ahead logged and their
use being discouraged has been removed.  "snapshot too old" is now
supported for tables with hash indexes.  Most importantly, barring
bugs, hash indexes will now be crash-safe and usable on standbys.

This commit doesn't yet add WAL consistency checking for hash
indexes, as we now have for other index types; a separate patch has
been submitted to cure that lack.

Amit Kapila, reviewed and slightly modified by me.  The larger patch
series of which this is a part has been reviewed and tested by Álvaro
Herrera, Ashutosh Sharma, Mark Kirkwood, Jeff Janes, and Jesper
Pedersen.

Discussion: http://postgr.es/m/CAA4eK1JOBX=YU33631Qh-XivYXtPSALh514+jR8XeD7v+K3r_Q@mail.gmail.com

1 files changed, 133 insertions, 1 deletions

diff --git a/src/backend/access/rmgrdesc/hashdesc.c b/src/backend/access/rmgrdesc/hashdesc.c
index 7eac8191cad..f1cc9ff9514 100644
--- a/src/backend/access/rmgrdesc/hashdesc.c
+++ b/src/backend/access/rmgrdesc/hashdesc.c
@@ -19,10 +19,142 @@
 void
 hash_desc(StringInfo buf, XLogReaderState *record)
 {
+	char	   *rec = XLogRecGetData(record);
+	uint8		info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+	switch (info)
+	{
+		case XLOG_HASH_INIT_META_PAGE:
+			{
+				xl_hash_init_meta_page *xlrec = (xl_hash_init_meta_page *) rec;
+
+				appendStringInfo(buf, "num_tuples %g, fillfactor %d",
+								 xlrec->num_tuples, xlrec->ffactor);
+				break;
+			}
+		case XLOG_HASH_INIT_BITMAP_PAGE:
+			{
+				xl_hash_init_bitmap_page *xlrec = (xl_hash_init_bitmap_page *) rec;
+
+				appendStringInfo(buf, "bmsize %d", xlrec->bmsize);
+				break;
+			}
+		case XLOG_HASH_INSERT:
+			{
+				xl_hash_insert *xlrec = (xl_hash_insert *) rec;
+
+				appendStringInfo(buf, "off %u", xlrec->offnum);
+				break;
+			}
+		case XLOG_HASH_ADD_OVFL_PAGE:
+			{
+				xl_hash_add_ovfl_page *xlrec = (xl_hash_add_ovfl_page *) rec;
+
+				appendStringInfo(buf, "bmsize %d, bmpage_found %c",
+						   xlrec->bmsize, (xlrec->bmpage_found) ? 'T' : 'F');
+				break;
+			}
+		case XLOG_HASH_SPLIT_ALLOCATE_PAGE:
+			{
+				xl_hash_split_allocate_page *xlrec = (xl_hash_split_allocate_page *) rec;
+
+				appendStringInfo(buf, "new_bucket %u, meta_page_masks_updated %c, issplitpoint_changed %c",
+								 xlrec->new_bucket,
+					(xlrec->flags & XLH_SPLIT_META_UPDATE_MASKS) ? 'T' : 'F',
+								 (xlrec->flags & XLH_SPLIT_META_UPDATE_SPLITPOINT) ? 'T' : 'F');
+				break;
+			}
+		case XLOG_HASH_SPLIT_COMPLETE:
+			{
+				xl_hash_split_complete *xlrec = (xl_hash_split_complete *) rec;
+
+				appendStringInfo(buf, "old_bucket_flag %u, new_bucket_flag %u",
+							 xlrec->old_bucket_flag, xlrec->new_bucket_flag);
+				break;
+			}
+		case XLOG_HASH_MOVE_PAGE_CONTENTS:
+			{
+				xl_hash_move_page_contents *xlrec = (xl_hash_move_page_contents *) rec;
+
+				appendStringInfo(buf, "ntups %d, is_primary %c",
+								 xlrec->ntups,
+								 xlrec->is_prim_bucket_same_wrt ? 'T' : 'F');
+				break;
+			}
+		case XLOG_HASH_SQUEEZE_PAGE:
+			{
+				xl_hash_squeeze_page *xlrec = (xl_hash_squeeze_page *) rec;
+
+				appendStringInfo(buf, "prevblkno %u, nextblkno %u, ntups %d, is_primary %c",
+								 xlrec->prevblkno,
+								 xlrec->nextblkno,
+								 xlrec->ntups,
+								 xlrec->is_prim_bucket_same_wrt ? 'T' : 'F');
+				break;
+			}
+		case XLOG_HASH_DELETE:
+			{
+				xl_hash_delete *xlrec = (xl_hash_delete *) rec;
+
+				appendStringInfo(buf, "is_primary %c",
+								 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;
+			}
+	}
 }
 
 const char *
 hash_identify(uint8 info)
 {
-	return NULL;
+	const char *id = NULL;
+
+	switch (info & ~XLR_INFO_MASK)
+	{
+		case XLOG_HASH_INIT_META_PAGE:
+			id = "INIT_META_PAGE";
+			break;
+		case XLOG_HASH_INIT_BITMAP_PAGE:
+			id = "INIT_BITMAP_PAGE";
+			break;
+		case XLOG_HASH_INSERT:
+			id = "INSERT";
+			break;
+		case XLOG_HASH_ADD_OVFL_PAGE:
+			id = "ADD_OVFL_PAGE";
+			break;
+		case XLOG_HASH_SPLIT_ALLOCATE_PAGE:
+			id = "SPLIT_ALLOCATE_PAGE";
+			break;
+		case XLOG_HASH_SPLIT_PAGE:
+			id = "SPLIT_PAGE";
+			break;
+		case XLOG_HASH_SPLIT_COMPLETE:
+			id = "SPLIT_COMPLETE";
+			break;
+		case XLOG_HASH_MOVE_PAGE_CONTENTS:
+			id = "MOVE_PAGE_CONTENTS";
+			break;
+		case XLOG_HASH_SQUEEZE_PAGE:
+			id = "SQUEEZE_PAGE";
+			break;
+		case XLOG_HASH_DELETE:
+			id = "DELETE";
+			break;
+		case XLOG_HASH_SPLIT_CLEANUP:
+			id = "SPLIT_CLEANUP";
+			break;
+		case XLOG_HASH_UPDATE_META_PAGE:
+			id = "UPDATE_META_PAGE";
+			break;
+	}
+
+	return id;
 }